SAP Contact Center 7 Infrastructure Overview · 2019-11-12 · SAP Contact Center infrastructure is...

©SAP AG 2007

SAP CONTACT CENTER

INFRASTRUCTURE

Software version 7.0

Document version 1.1

© SAP AG

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CONTENTS

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1 Introduction to SAP Contact Center infrastructure 5

1.1 Introduction to site landscapes and connectivity 5

1.2 Introduction to environmental and facility recommendations 7

1.3 Introduction to server hardware, operating systems and software 7

1.4 Introduction to gateways and SIP trunks 8

1.5 Introduction to data center LAN 8

1.6 Introduction to customer LAN 10

1.7 Introduction to storage systems 12

1.8 Introduction to telephony and data connections 12

1.9 Introduction to user terminals 13

1.10 Introduction to security 13

1.11 Introduction to availability and manageability 14

1.12 Introduction to deployment, software distribution and configuration 15

1.13 Introduction to sizing 16

2 Site landscapes and connectivity. 18

2.1 Modules 18

2.2 Communication Channels 20

2.3 Virtual units 20

2.4 Interconnecting SAP Contact Center systems 22

3 Environmental and facility recommendations 23

3.1 Physical security 23

3.2 High availability 24

4 Server hardware, operating systems and software 26

4.1 Servers 26

4.2 Operating systems 32

4.3 Software 32

5 Gateways and SIP trunks 36

5.1 Distributing gateways and SIP trunks 36

5.2 Connecting to a PBX 37

5.3 Miscellaneous settings 39

5.4 Cisco gateways 39

6 Data center LAN 40

6.1 Performance 40

6.2 Availability 42

6.3 Multiple Sites 45

7 Customer LAN 50

7.1 Availability 50

7.2 Ability to carry voice 50

8 Storage systems 52

8.1 RAID arrays 52

8.2 SAN systems 52

CONTENTS

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9 Telephony and data connections 53

9.1 Telephony connections 54

9.2 Data connections 54

10 User terminals 57

10.1 CDT and Convergence 57

10.2 IP Desk Phones 57

11 Security 59

11.1 Network traffic control 59

11.2 Identification, authentication and authorization 59

11.3 Signed software modules 59

11.4 Encrypted network traffic 59

12 Availability and manageability 60

12.1 SAP Contact Center HAC 60

12.2 SAP Contact Center Alarm Server 61

12.3 SNMP 61

12.4 Miscellaneous 62

13 Deployment, software distribution and configuration 63

13.1 Software distribution 63

14 Sizing 64

15 Interoperability with other systems 65

16 Glossary 67

17 Appendix A: Sample SAP Contact Center Servers 76

17.1 Basic service provider setup using Windows Server 2008 76

17.2 Service provider setup with SAN using Windows Server 2008 77

INTRODUCTION TO SAP CONTACT CENTER INFRASTRUCTURE

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1 Introduction to SAP Contact Center infrastructure

The SAP Contact Center (SAP CCtr, formerly SAP BCM) software provides a multi-channel, all-IP communications platform for customer care operations. With SAP Contact Center organizations can deploy IP telephony for everyone who needs it, including telemarketing experts, customer service agents, switchboard operators, office workers, mobile experts, and their managers. SAP Contact Center is the telecommunication technology of today. It is a single integrated system based on open IT standards and enables customers to

Manage phone calls, emails, short messages and web contacts in a single, software-based solution.

Utilize a full range of communication devices such as soft phones on PC desktops, IP desk phones and mobile phones.

Connect mobile and globally scattered workforce.

Manage distributed know-how and utilize the right people with the right skills from front-office agents to back-office specialists.

Smooth migration, security, reliability and scalability upon deployment.

SAP Contact Center infrastructure is everything that is needed to run the SAP Contact Center software, such as servers, networks, gateways and terminals. An enterprise can set up a SAP Contact Center in-house system or a service provider can offer SAP Contact Center functionality to end customers. In-house and service provider setups are basically similar and the main differences are due to service providers striving towards multitenant and/or multi-instance setups to achieve cost efficiency and simultaneously facing a variety of and sometimes even contradictory end user requirements. While an in-house system does not logically differ from a hosted service entity providing the same service, an in-house system may be considered more stable in terms of various software and hardware updates. This puts harder requirements on operations and manageability for service providers who, on top of this, have their own requirements on for example scalability, security and total cost of ownership (TCO).

1.1 Introduction to site landscapes and connectivity

A SAP Contact Center system is comprised of Windows servers running Microsoft SQL, Microsoft Internet Information Server (IIS) and SAP Contact Center. Clients are soft phones (PC) and IP desk phones. In addition, there are gateways or SIP trunks carrying external calls to and from the SAP Contact Center system to the public switched telephone network (PSTN) and IP networks interconnecting the servers, gateways and user terminals.

SQL

Server

SAP CCtr & IIS

Server

PSTN

PLMN

PRI

GATEWAY

- Electrical and mechanical adaptation

-ISDN Q.931 to/from SIP or H.323

conversion (signalation)

- 64 kbit/s PCM to/from G.711

conversion (audio stream)

Client

100/1000Base-T Ethernet

IP v4

PSTN/PLMN subscribers

SIP / IP desk

phoneCDT terminals

PSTN

PLMN

Session Border Controller

- Protocol normalization

- Transcoding

- Security policies enforcement

SIP

Trunk

Figure 1. A Basic SAP Contact Center in-house landscape.

Figure 1 shows a basic SAP Contact Center in-house landscape in which a voice over IP (VoIP-) gateway is


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connected to the telephone network over a 2 Mbit/s PRI line. The gateway adapts the protocols and characteristics on the PSTN side to those used on the local area network (LAN) side. The PRI line is provided by a telco and a telephone number range is normally included with the subscription. The gateway and the LAN is setup and maintained by the Enterprise. Nowadays SIP trunks and Session Border Controllers (SBC) are often used instead of PRI lines and gateways. In this simplified landscape illustrating the principles, the SAP Contact Center Server contains any required SAP Contact Center modules and integration interfaces whereas the SQL Server contains operational and reporting databases. Real setups might contain separate SQL Servers for operational and reporting purposes and SAP Contact Center components might be distributed over two or more servers depending on performance, administrative, security etc. conditions.

SQL

Server

SAP CCtr & IIS

Server

(CS, MRS,

SBR, ETC,

Integration Interfaces, ...)

GATEWAY

PSTN

PLMN

PRI

Client

100/1000Base-T

Ethernet IP v4

Inside Network

PSTN/PLMN subscribers

SIP / IP/

phone

CDT terminals


IP v4

WAN

Service link

Access link


IP v4 Access Network

SAP CCtr

Server

(CEM, CD, HAC, AS, IA, ...)

SBC

SIP

Trunk

Figure 2. A Basic SAP Contact Center service provider landscape.

Figure 2 shows a basic SAP Contact Center service provider landscape. The service provider could equally well be an external commercial service provider or an internal corporate department providing the service to other departments. It contains the same SAP Contact Center components as the in-house landscape.


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Terminals and users reside in an enterprise network connected to a service provider network over a wide area network (WAN) connection. Multitenant and/or multi-instance setups are key issues for a service provider to achieve acceptable TCO. To be able to run several customers securely on a shared infrastructure, the service provider network is compartmentalized into an inside network and an access network. Direct customer access is restricted to SAP Contact Center components in the access network only on an as-needed basis and SAP Contact Center components in the access network are granted access to resources in the inside network on an as-needed basis. The multitenant and/or multi-instance architecture allows for several customers to share common service provider equipment and resources, such as servers and networks, facilitating service provider efficiency and competitiveness on the market.

Chapter 2, Site landscapes and connectivity covers this topic in more detail.

1.2 Introduction to environmental and facility recommendations

The nature of SAP Contact Center services, dealing with phone calls and other communications channels, makes it business critical. Because the availability of SAP Contact Center services depends on the underlying infrastructure, these aspects have to be taken into consideration in the infrastructure.

Some environmental and facility requirements are dictated by server and network equipment manufacturers and are based on requirements from semiconductor and component manufacturers. Required operating conditions such as temperature and humidity must be matched and power must be supplied for the services to run. Available options are, for example, measures for power failures, alternate call routing and supplying power for emergency calls.

Some requirements may arise from legislation, corporate security policies and risk management. These may include administrative roles, passage control and site locations. Environmental and facility requirements should only partly be considered technical IT issues because they are also business strategy issues and dealing with them is company and service provider individual.

Chapter 3, Environmental and facility recommendations, covers this topic in more detail.

1.3 Introduction to server hardware, operating systems and

software

SAP Contact Center servers run the SAP Contact Center software and related Microsoft IIS and Microsoft SQL Server on industry standard x86 or x64 based server hardware. Servers and desktops are engineered for different usage. Servers are specifically designed to hold, manage, send and process data. The technologies behind servers make them more reliable and scalable than desktop systems and help them process data faster and more efficiently than desktop systems. One significant benefit of servers is that their configurations can be customized to meet very specific needs, such as disk I/O and/or capacity, so servers can be designed to provide maximum return for the investments.

Deciding the needed server setup requires investigation in and awareness of, for example, estimated capacity demands in terms simultaneous phone calls, number of users and customers. Affecting factors may have very different importance in different setups. Some factors might be relatively static for enterprises providing the services internally and some might be even unforeseeable for service providers. Especially service providers should consider their estimated growth speed, scaling strategy and intended service level agreements (SLA). An in-house system might consist of a couple of entry-level servers whereas a service provider might run clustered SQL databases, distribute SAP Contact Center components over several servers, provide failover nodes for each and benefit from fault-tolerant LAN’s and fault-tolerant high performance storage area networks (SAN).

Supported and recommended hardware, operating systems and software can be found in the infrastructure compatibility list (ICL) in the support portal. Appendix A presents some Sample SAP Contact Center server configurations.

Chapter 4, Server hardware, operating systems and software covers this topic in more detail.


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1.4 Introduction to gateways and SIP trunks

PSTN networks are connected to IP networks through VoIP-gateways. Gateways provide electrical and mechanical adaptation between the two networks and perform protocol and voice stream translation as figure 3 shows.

VoIP GATEWAY

10/100 Base-T Ethernet

to IP network

E1, T1 or J1 line

to PSTN

Q.931

Q.921

64 kbit/s PCM

56 kbit/s PCM

DHCP, TFTP

TELNET

HTTP

SIP, H.323

G.711, G.729

........

Figure 3. Gateways provide electrical and mechanical adaptation between PSTN and IP/Ethernet networks and perform protocol and voice stream translation.

SAP Contact Center supported gateways are available with support for E1, T1 and J1 PRI lines to the PSTN. E1 lines are used in Europe, T1 in America and J1 in Japan.

One E1 line may be channelized into 32 DS0 channels, one of which is used for synchronization, one as the D-channel (signaling channel) and 30 as bearer channels for voice streams (phone calls). One T1 or J1 line may be channelized into 24 DS0 channels, one of which is used as the D-channel.

Gateways are connected to IP networks with 10/100/1000 Base-T Ethernet links. Gateways are controlled by SAP Contact Center using the protocols SIP or H.323. Gateways typically support at least dynamic host configuration protocol DHCP for IP address provisioning, trivial file transfer protocol (TFTP) for configuration provisioning and Telnet for configuration. Most gateways also provide a web interface for administration and configuration.

Gateways may be distributed geographically, for example, over different telco areas or to different satellite sites of a service provider or customer. This allows local calls to satellite sites and enables cost optimization by routing calls over IP to the most profitable gateway. Distribution of gateways may thus influence telephony costs and may also have positive impact on failure resistance and data line bandwidth demands. Gateways may also be connected to private branch exchanges (PBX) over PRI enabling calls between legacy telephony systems and VoIP systems. In fact, interconnecting the two systems is a commonly used method allowing for flexible migration phases.

SIP trunks have become a popular alternative to PRI lines, especially in new setups. A SIP trunk setup reminds topologically of a PRI setup but the PRI is replaced with an IP connection and, in most cases, the gateway is replaced with a SBC. Some SIP trunks are supported even without a SBC in between.

Chapter 5, Gateways, covers gateways in more detail. Chapter 9, Telephony and data connections, covers PSTN lines in more detail.

1.5 Introduction to data center LAN

Data center LAN refers to the LAN, where the SAP Contact Center Servers reside and where the SAP Contact Center services are produced. Although emphasis here is on service provider data center LANs, this information might give enterprises ideas when designing their in-house landscapes.

High service availability and manageability are crucial for a service provider. Among many other things, service supply and underlying infrastructure have to be carefully designed to meet market demands. Growth strategies


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have to be prepared and risk mapping must be done. Various problem scenarios are covered by building fault tolerance and automatic or manual failover mechanisms. Nevertheless, a service provider providing numerous customers’ with business critical communications services is encouraged to prepare for the unexpected and narrow down the impacts of service supply failures. This can be done for example by segmenting the production environment into more or less self-sufficient production units constricting the impacts of a failure of one production unit from other production units. To be self-sufficient, a unit would include all layers from the bottom of the infrastructure all the way to the service interface towards the customer. It is an ongoing task of growth, risk and business management to decide how many production units to run, how to design them and when to start new ones. Figure 4 shows one approach of segmenting the data center LAN.

Customer A

Core Network

Customer B Customer C Customer D Customer E

Access

Network

Customer E

Service

realization

Customer A

Service

realization

ADSERVER(S)

SAP CCtrSERVER(S)

SAP CCtr IIS SAP CCtr IIS

SAP CCtr IIS

SAP CCtr IIS

SAP CCtr IIS

SAP CCtr IIS

SAP CCtr IIS SAP CCtr IIS

SQLCLUSTER

MGMTSERVER

SAP CCtrSERVER(S)

Medium Network

Figure 4. A sample segmentation model of data center LAN. The middlemost area constitutes a fault-tolerant core network all services depend on. The next orbit is a medium network for purposes of separating the core network from the outermost access network, where the services are made available for the customers. The green and red areas, service realizations, describe the required portion to produce a service for a customer. The landscape conforms to the basic service provider landscape shown in figure 1, except for the missing CMC option.

Chapter 6, Data center LAN, covers this topic in more detail.


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1.6 Introduction to customer LAN

The customer LAN refers to the LAN where the SAP Contact Center service is consumed. In an in-house installation, SAP Contact Center services are also produced locally in the customer LAN. If SAP Contact Center services are provided by a service provider, the customer LAN is connected to the SAP Contact Center service with an access link and optional back-up links. Multi-office customers have the options to access SAP Contact Center services via access links to each office or via WAN/MAN links interconnecting the offices to a common access link or via any combination of these.

Access link

Service link

PSTN

WAN

Data center

LANSQL

SAP CCtr & IIS

GW or SBC

Customer

LANClient

PRI or SIP trunks

Figure 5. A single site customer LAN connected to a SAP Contact Center service provider.

Figure 5 shows a single site customer LAN connected to a SAP Contact Center service provider. All services are provided from the data center LAN and accessed over a WAN connection by users in the customer LAN.

External telephony is routed over one or more PRI (E1/T1/J1) connections or SIP trunks to/from the PSTN. The subscriber of the PRI connection / SIP trunk is typically the customer but it may also be the service provider and the same applies to the access link, which may be any link capable of providing sufficient bandwidth and performance, such as a point-to-point or a multi protocol label switching (MPLS) link.

The service provider is responsible for keeping the services up and running by performing various daily maintenance tasks and production environment reassessment as service demands increase and thus maintaining acceptable and agreed service levels.

The telcos and/or ISPs are responsible for the operability and service levels of data and telephony links. The subscriber of the links is responsible for the suitability and sufficiency of the subscribed links.

The most demanding requirement regarding the data link and the LANs, besides the overall operability, is the ability to carry real-time streams without introducing unacceptable delays or delay variations (jitter). The customer is responsible for maintaining the customer LAN´s capability of carrying voice traffic with acceptable quality.

As a rule of thumb, well performing switched 100 Base-T and 1000 Base-T networks are well fitted for IP telephony.


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Access links

Service link

WAN

Site 1

LANClient

Site 3

LANClient

Site 2

LANClient

Enterprise

Network

Figure 6. A multi-site customer LAN with one access link per site.

Service link

WAN

Site 1

LANClient

Site 3

LANClient

Site 2

LANClient

Enterprise

Network

Figure 7. A multi-site customer LAN with one common access link.

Figure 6 shows a landscape of a customer with three sites, each connected directly to the SAP Contact Center service provider. External telephony is routed over the access links. Internal telephony may be routed over the access links or links interconnecting the sites. Back-up connectivity may be provided over the links interconnecting the sites.

Figure 7 shows a landscape of a customer with three sites sharing a common access link to the SAP Contact Center service provider. Links interconnecting the sites must be dimensioned for carrying the telephony traffic and back-up routes and/or access links should be considered.

Sorting out the most suitable approach for each case involves investigating the current enterprise network topology and its fault tolerance, finding out user concentrations and estimating the bandwidth demand on different parts of the network. Also, existing traffic profiles and regular and casual peak loads should be considered especially on interconnecting links, which often are slower than the site LANs. Quality of service (QoS) controls may be applied to the interconnecting links and sometimes to the site LANs as well.

In general, there are three factors deteriorating voice quality in a network point of view. They are too long one-way delay, packet loss and jitter. One way delay problems suggest network design problems and that fundamental incompatibility exist between the current network implementation and the demand of carrying quality voice over it. For example, it could be a too slow link over a too long distance without even theoretical ability to achieve demanded performance.

Packet loss or extensive number of retransmissions and cyclic redundancy check (CRC) errors implies hardware or configuration problems, such as speed or duplex mismatches, poor connectors, damaged or poorly mounted cabling or exceeded environmental conditions. These two problem types, too long one-way delay and packet loss, including retransmissions and CRC errors, are remedied by one time actions. Once the root cause is identified, the problem is solvable permanently. Drops can be monitored in many ways, for example routers and switches usually have drop counters. Too long one-way delay is immediately recognized by overlapping speakers. Delays can be estimated from the round trip shown by ping.

Jitter is variation of one-way delay and is compensated to a limited extent by jitter buffers on gateways and terminals. A constant stream of digitized voice data must be supplied to an AD converter in order to get constant analog sound. If the digitized voice stream is interrupted or delayed, there will be an outage on the analog sound deteriorating the voice quality. Jitter problems can be remedied by applying QoS controls and revising network topologies to minimize congestions.

Chapter 7, Customer LAN, covers this topic in more detail.


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1.7 Introduction to storage systems

Storage systems refer here to hard disk storage used by SAP Contact Center and underlying infrastructure for saving operating systems, applications and data. Storage is necessary for each server, but storage capacity, performance requirements and availability requirements may vary depending on server roles and utilization. Storage design may also impact how servers are managed and maintained.

SAP Contact Center allows for setups with redundant servers. This means that there are preconfigured up-to-date failover servers available in case of server crashes. These, kind of disposable, servers should not contain any user data, such as recorded files, voicemails or attachments. Neither should they contain any usage data that is not affordable to be lost in case of a server crash.

All failover events are not invisible to users and securing server storage improves reliability and eases system maintenance. This can be done using fault-tolerant disk configurations such as

- RAID-1

- RAID-5

- RAID-10

Some data must be made available for all servers sharing a common role, such as SQL servers and file servers. For example, if a SQL Server cluster node fails, a back-up node must be able to mount the storage and access the database. Clustered server packages with integrated disk arrays constitute one possibility to fulfill this requirement. Another possibility is to use Storage Area Networks (SANs).

SANs provide centralized storage capacity to distributed servers in such a way that the storage seems to be locally attached in the operating systems point of view. Servers can be booted from SANs so SANs makes it possible to use diskless servers, in the sense that no disks are installed physically in the server.

This approach allows servers to be easily replaceable “dummy” electronics boards that are ever less individualized or designated for any specific task, potentially giving more flexibility in production operations, upgrades and scaling tasks. SANs provide high performance disk I/O. Servers are connected to the SANs with Fibre Channel links or Ethernet links. In the former case the server requires a host bus adaptor (HBA).

SANs introduce a potential for regarding different life spans for servers and storage. Although a SAN system is scalable itself and there are different classes of SANs, a SAN system is one of the biggest single investments in a SAN-based SAP Contact Center infrastructure. Whilst being that, a longer life span should be considered for a SAN than for a server as perfectly intact servers grow old as operating systems and applications evolve.

Chapter 8, Storage systems, covers this topic in more detail.

1.8 Introduction to telephony and data connections

Data links refer to access and service links connecting the customer LAN to the data center LAN and carrying voice streams, signaling information and UI data to/from SAP Contact Center servers, gateways and SBCs from/to SAP Contact Center user terminals, such as soft phones and IP desk phones.

Telephony links refer to E1/T1/J1 PRI links and SIP trunks carrying phone calls between gateways/SBCs and the PSTN. SAP Contact Center does not directly require any special technology for data links as long as sufficient IP performance is provided and the same applies to the PRI links as long as the gateways they are connected to provide SIP or H.323 over IP on the network side.

SAP Contact Center supported gateways support ISDN PRI E1/T1/J1 telephony links. Telephony links are provided by a telco/ISP and telephone number ranges are allocated to each link or group of links. Telephony


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links, may be concentrated in a data center or distributed to customer premises, branch offices or other points of presence. For availability purposes, telephony links may also be distributed over two or more telephone exchanges or sometimes even over two or more telcos.

Access and service links are required in service provider cases only. For a service provider, it is often reasonable to build a high-density service link to one or more ISPs and have them provide the access links to the customers. If telephony links are centralized in the data center, all SAP Contact Center related traffic will pass over the service and access links. If telephony links are distributed to customer locations, a relevant part of the voice streams may exist only inside the customer LAN and thus access link bandwidth demand may decrease.

Deciding the capacity and the customer side endpoint of the access link involves estimation of the maximum number of simultaneous calls and call density estimations per locations in order to find the most suitable endpoint location. Minimizing the network distance between the endpoint and the call density center allows for maximum average call quality expectations.

Chapter 9, Telephony and data connections, covers this topic in more detail.

1.9 Introduction to user terminals

There are two types of user terminals, soft phones and IP desk phones.

Communication Desktop (CDT) is the SAP Contact Center Microsoft IE browser based soft phone including numerous features such as directories and PRS (presence) profile management. A handset or headset is used with CDT. The handset/headset connects to a USB port of a PC either directly or via an adaptor performing the analog-to-digital (A/D) transformation.

Supported IP desk phones are SIP phones. IP desk phones are voice stream and signaling information endpoints and they are quite independent units resembling legacy telephone terminals. They do not provide the advanced features of CDT.

Chapter 10, User terminals, covers this topic in more detail.

1.10 Introduction to security

SAP Contact Center provides telephony over IP and is normally used in private networks but not in public networks such as the Internet. SAP Contact Center includes security instruments itself, such as identification, authentication and encryption, but it relies also on security mechanisms in the underlying infrastructure.

In general, security aspects are present in several different levels and viewpoints. The primary concern of a service provider might be to ensure the availability and integrity of the data center, that is, their business and the services provided to customers, whereas the concerns of the customer might be availability and confidentiality. Although the slightly different security viewpoints affect the security issue, overall security must be considered and both service provider and customer demands must be met.

When the service is provided by a service provider and utilized by an end user, it is obvious that security roles and responsibilities are divided to both parts. From the network landscape it can be observed that the data connection between the data center and the service provider poses a potential threat from the service provider to the customer and vice versa.

Important security mechanisms are access lists, traffic filtering and virtual LAN (VLAN) segmentation. Figure 8 gives an overview of protocols used by SAP Contact Center. Signed soft phone and mobile terminal components assure the integrity and the manufacturer of the components. Server side authentication is achieved by certificates from trusted certificate authorities.


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PSTN

Data Center LAN

Customer LAN

H.323 Bridge

SIP

RTP

SIP RTP

WACP

SIP Bridge

WACP

SIP

H.323 Gateway

H.323

RTP PRI

SQL

CEM&CD

WEB

CDT

CDT

CDT

http(s)

RT

PR

TP

ODBC

ODBC

RTP

WACP

Figure 8. An overview of protocols used by SAP Contact Center.

Chapter 11, Security, covers this topic in more detail.

1.11 Introduction to availability and manageability

High availability in this context refers to high availability of service achieved by introducing fault tolerance and disaster recovery. The fault tolerance architecture attempts also to provide good manageability. The idea is to have a fault tolerant architecture performing manual and/or automatic failovers but unlike probably most cases, not to do fallbacks. Failover may occur due to failures or avoidance of down-times during maintenance tasks and therefore a more appropriate term than failover is switchover.

Interactions and attitudes of individuals can devastate even the best systems or make the worst possible systems appear excellent. Therefore, it is important to understand existing fault tolerance and its entities, mutual impacts between systems and/or their components and to undertake working methods to support aspired service levels. High availability is not reachable with technical measures alone.

Enabling switchover operations due to maintenance task and/or failures requires that the ability to produce a service exists in two or more places. The ability to produce a service includes CPU power, storage, configuration data and network connectivity and so on. Making this ability generally available for all services requires good management of SAP Contact Center infrastructure, awareness of available resources, awareness of the committed service levels, proactive approaches in developing the infrastructure, engagement


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in undistorted working methods and continuous testing. The idea of using only switchovers and not fallbacks is an important part of testing. Switchover moves the source of the service in question from one entity to another and thus tests the entities.

Adapting the switchover mechanism to version updates can result in that live production entities are never updated. Arranging for a group of at least three similar service entities, one being active and two being standby, enables to apply an update and to test it with minimal downtime. The update is applied to one of the standby entities to which cannot be switched over to during the update. The other standby entity is there in case of a failure of the active entity during the update.

Once the update is applied, the entity can be tested, even by the customer, and when it is approved, a switchover is performed to the updated entity. One of the remaining entities needs to be updated as well to provide an equal version switchover entity. Eventually, the old entities and related resources are freed and available for other updates.

The described updating and maintenance practice allows for the actual updates and maintenance tasks being performed during normal office hours without having to adapt to maintenance windows and strict time frames. The update experienced by the user is only a rapid switchover.

SAP Contact Center provides management tools only for the application, such as:

- High Availability Controller (HAC)

- Infrastructure Administrator (IA)

- System Configurator (SC)

Management tools for the infrastructure are provided by each device manufacturer or some third party provider.

These tools include Telnet and/or browser-based device configuration and server management tools, such as HP server management tools, simple network management protocol (SNMP) agents by hardware manufacturers and SNMP management software.

High availability includes also ensuring quality voice in the customer LAN by implementing QoS. This protects against voice quality impairments due to heavy network bandwidth consumption which may be caused by new or improperly configured software or increased usage of existing software.

Chapter 12, Availability and manageability, covers this topic in more detail.

1.12 Introduction to deployment, software distribution and

configuration

SAP Contact Center deployment is a manifold task. It starts by finding out and defining the particular service to be provided and its various parameters, such as:

- Schedules

- Queues

- Prompts

- Telephone number ranges and call volumes

When call volumes and server and agent locations are recognized, the network topology is decided. This includes deciding the number of telephony links and their locations and when this is done, the number of required access links and their capacities can be decided. Also high availability requirements affect the


16

designing phase in terms of volume, number of access and telephony lines and number of servers used. One important decision is whether to provide full or partial capacity in a failure situation. Full capacity means that for at least most resources, double capacity is at hand when operating normally. These are crucial steps that might have undesired impact if they are poorly designed and/or implemented.

Deployment also includes decisions on what terminals and accessories to use, such as the type of handsets and/or headsets to be used with CDT and deciding the type of IP desk phones and to purchase these.

Once the above steps are completed, access lists can be designed. Typically, there is a firewall, router or layer 3 switch providing access control between the users and the servers. The particular access control configuration depends on the used IP address ranges, the terminal and gateway or SBC models and their configurations and the used protocols.

The SAP Contact Center related client software is needed mainly by CDT. These are ActiveX components available as msi files. The SAP Contact Center ActiveX components are signed by SAP Labs Finland to convince the user of their trustworthiness. These components can be distributed in any way suitable, e.g. using Microsoft systems management server (SMS) or by installing copying them manually to each workstation. All CDT configurations are done within CDT or via SAP Contact Center Management utilities by an administrator. IE, local firewall and so on configurations are done with the respective software.

IP desk phone configurations are done manually using the keypad or (semi)automatically using DHCP, TFTP, Telnet and/or browser-based administration tools. The facilities vary slightly between different manufacturers. So far the soft phone is clearly the dominating terminal and IP desk phone configurations have mostly been made manually using the keyboard of the phone and/or using a browser.

Chapter 13, Deployment, software distribution and configuration, covers this topic in more detail.

1.13 Introduction to sizing

Sizing involves various capacity requirements of components and devices constituting an operational SAP Contact Center system, such as telephone links, access links, customer and data center LANs, gateways and servers.

The resource requirements of different SAP Contact Center components and the capacity they provide are discussed here, for example a SIP bridge (SBR) can handle a maximum of 700 simultaneous SIP calls. Sizing does not take count in capacity requirements for high availability solutions, it tells only what is required and achieved by a single component or device. Spare and failover capacity has to be considered separately.

Scaling goes closely along with sizing and is covered as well. Especially for a service provider it is crucial to consider scaling from the very beginning and to design the system accordingly in order to maximize cost efficiency and prepare for future increases.

Since the current hardware development is rapid it would be easy to believe that hardware investments made in advance are not profitable. However, over time hardware does not constitute the most expensive portion of the business and standardizing might increase working efficiency and thus give savings in labor costs.

Designing a SAP Contact Center infrastructure that has high availability and is scalable should start with recognizing some goals and margins, such as estimated total volumes in terms of:

- Customers

- End users

- Data lines

- Telephony lines


17

Particularly important is also to estimate the life cycle of the SAP Contact Center technical infrastructure, for example a storage system may serve significantly longer than a server that might become outdated in three years.

Sizing rules are not always so simple and unambiguous because the usage pattern may vary a lot from case to case depending on for example the implemented integrations channels. Especially e-mail channels and channels that are converted into e-mail channels, such as web channels, may deal with numerous attachments of various sizes that consume storage and network capacity.

To throw some light on sizing as number of servers, there are implemented systems with one Microsoft SQL Server (cluster) and two SAP Contact Center servers perfectly dealing with up to 660 simultaneous calls and there are systems where additional three servers have been installed as SIP and/or H.323 bridges dealing with 2000 simultaneous calls. Factors such as higher redundancy demands and backup sites may require additional servers to be installed.

Usually the most expensive servers are high end, SAN attached and clustered Microsoft SQL servers and SAP Contact Center application servers are more affordable.

Chapter 13, Sizing, covers this topic in more detail.

SITE LANDSCAPES AND CONNECTIVITY

18

2 Site landscapes and connectivity.

Basic in-house and service provider landscapes are shown in section 1.1, Introduction to site landscapes and connectivity. This chapter explains what modules are used and for what purposes, how different channels are implemented and how virtual units (VU) are used.

The specific behavior and functionality of any SAP Contact Center system is determined by the set of modules used and their configurations. Any specific module is responsible for a logical set of functionality, for example, if there is a demand for sending SMS messages, the SMSServer module is needed.

Channels refer to communications channels used to communicate externally and/or internally such as telephony, fax and email.

Virtual units are used for administrative grouping of services. In a multitenant environment, where several customers are served by the same hardware, virtual units are assigned customer specific resources such as IP-addresses, directories and other settings.

2.1 Modules

A SAP Contact Center module is discrete product module run as a process. Modules are run in some virtual unit’s context, which typically contains its own resources such as IP-addresses, log file directories and configuration data.

2.1.1 Human interface modules

Human interface modules are a set of mostly web browser-based user interfaces that provide the end users to access phone, directory and call history functionality and administrators to access administrative functions. These modules are:

CDT (Communications desktop) is the SAP Contact Center soft phone and the primary graphical user interface.

Convergence is an alternative soft phone suitable for the basic telephony users.

Monitoring allow contact center supervisors to monitor service metrics.

Infrastructure Administrator (IA) is for controlling and monitoring SAP Contact Center software, for example managing services, platforms, virtual units, web sites and viewing technical logs.

System Configurator GUI is for managing call switching and stream protocols, Queues, Services and SAP Contact Center Administrator accounts.

2.1.2 Service modules

Service modules are modules providing some specific functionality used directly by the user or indirectly by some other module. These modules are: (see also SAP Contact Center Master Guide)

Agent Server, provides services to agents via the Connection Server.

Alarm Server (AS), receives XML and/or HTTP alarms from any applications and filters and converts them to SMS, email and/or SNMP alarms/messages and forwards them to desired targets.

Batch Job Server

Call Dispatcher is for call routing, switching and control.

Chat Portal Server provides a Chat Portal Interface for integrating third party chat servers.

Chat Server manages chat discussions between participants.


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Configuration Database

Connection Server (CS) provides a secure TCP tunnel between clients and servers.

Contact Event Manager (CEM) is the core module of SAP Contact Center managing for example contact requests, queues and contacts event auditing.

Data Collector collects event data from various sources and stores them along with some pre-calculated aggregates into various databases.

Directory Database

Directory Server

E-mail Sender

External Terminal Controller (ETC) poses IP desk phones as CDT phones towards CEM.

File Replication Service (FRS) performs file replication between local/remote directories.

H.323 Bridge, (HBR) handles initiating, receiving, and controlling calls to/from H.323 gateways. It also contains an H.323 registrar. It performs protocol translation from H.323 to SAP Contact Center protocols and vice versa.

High Availability Controller (HAC) is for monitoring and controlling software processes and performing failover operations.

Integration Interfaces, (ACI, DAI, PSI, RDI, TMI)

Media Routing Server (MRS) is for handling audio and video streams to and from other modules or components.

Message to Mail (MsgToMail) sends e-mail messages from SAP Contact Center using SMTP (simple mail transfer protocol).

Monitoring Database stores and provides current statistics information.

Operative Database

Outbound Database, for outbound campaigns

Reporting Database stores and provides reporting information.

SAP CIC Adapter enables usage of SAP Contact Center contact center solutions as an integrated part of the SAP myCRM solution.

SIP Bridge, (SBR) handles initiating, receiving, and controlling calls to/from SIP gateways and IP desk phones. It also contains a SIP registrar and performs protocol translation from SIP to SAP Contact Center protocols and vice versa.

SMS Server sends SMS messages

Standard Reports

WebClient is an IIS extension module providing a scripting language for generating HTML and XML documents from data in databases and various HTML or XML templates.

Web Server

2.1.3 Integration interface modules

Online Interaction Interface Server provides Online Interaction Interface (OII) and Online Monitoring Interface (OMI).

SAP phone BCM provides the interface SAP phone statistics.

WS2 server provides Administration and Configuration Interface (ACI), Directory and Availability Interface (DAI), Presence Synchronization Interface (PSI), Reporting Data Interface (RDI) and Task Management Interface (TMI).


20

2.2 Communication Channels

The communication channels supported by SAP Contact Center are:

- Voice (telephony)

- E-mail

- Chat

- Web

- SMS (converted to and received as e-mail by SAP Contact Center))

- Fax (converted to and received as e-mail by SAP Contact Center)

Communications events from each channel are received and routed by SAP Contact Center according to predefined rules, such as timetables, queues and skills.

2.3 Virtual units

Virtual units are administrative groupings of services. A virtual unit is assigned an IP-address and it produces one or more one SAP Contact Center services (by installed software modules). A virtual unit is also a failover domain with one active instance and one or more failover instances. If any service or part of a virtual unit fails, the whole virtual unit fails and its services are activated in a failover instance. Failover proceedings may be automatically triggered by a monitoring event or they may be manual based on fault detection or maintenance requirements.

The naming convention of virtual units is free, but specially in service provider setups it is worth creating a naming convention suitable for supporting daily operations and maintenance. Logical and consistent naming convention eases recognition and thus decreases the risk of human errors.

A grouping of services and processes to virtual units based on their functionality and access requirements is recommended.

Grouping based on functionality can be as follows:

- VU_CORE for core components, such as CEM, CD and Data Collector

- VU_CONN for connectivity components, such as CS, ETC, SIP (for ETC) and Chat Server

- VU_BRIDGE for HBR, SBR and MRS

- VU_COM for communications components, such as SMS Engine

- VU_CEM_DB and VU_DPM_DB for databases.

Grouping based on access requirements can be as follows:

- VU_IWR for internal web services accessed by the system itself

- VU_WEB_ADMIN for administrative purposes and accessible only from the inside network

- VU_WEB_USER_CUSTOMER1 for end-user service access from customer1’s network

- VU_WEB_USER_CUSTOMER2 for end-user service access from customer2’s network

- VU_INT for integration services and interfaces accessible from the outside network, possibly one-to-one access.


21

CUSTOMER NETWORKUIs VUs

- CDT MRS

- Convergence SBR

- Monitoring

- IP Desk Phones

DMZ- VU_DMZ

Internet Chat Client

ACCESS NETWORK- VU_HAC - VUA

- VU_FRS_n - VU_INT

- VU_WEB_USER Web Server

Web Server Integration Interfaces

Web Clients Chat Portal Server

Repoting Web Clients - VU_TERMINAL_n

- VU_PSTN_n CS

SBR SBR (for ETC)

HBR - VU_WEB_REPORTING

MRS Web Server

Prompts Standard Reports

CORE NETWORK- VU_HAC

- VU_CORE - VU_FRS_n

CEM Server - PDC Server

Chat Server - VU_COM

ETC SMS Server

- VU_INTERNAL_n

Web Server - VU_Prompts

Internal Web Services Prompts

Data_Collector - VU_CEM_DB

- VU_CPM_DB CEM Database

CPM Database CEM_History_DB

- VU_Report_DB CEM_Reporting_DB

Reporting Database

WWU_DB

DSAREA_DB

APO_DB

MGMT NETWORK- VU_HAC

HAC

AS

* or if with AS failover *

- VU_HAC

HAC

- VU_AS

AS

- VUA

- VU_WEB_ADMIN

IA

Web Server

Web Admin Tools

- VU_CONN

- SNMP

- Network Admin Tools

- VoiceEdit

Figure 9. A SAP Contact Center virtual unit configuration sample.

Figure 9 shows a sample VU configuration. Capacity can be increased by configuring several VU’s for a particular task. Such VU’s can be named ending with an increasing number “_n”, for example, PSTN_1, PSTN_2, etc. It is recommendable to name the first virtual unit of a type as VU_1 although future virtual units would seem unlikely, because it makes it simpler to keep the naming convention later, if more virtual units are added after all.

The VUs in picture 9 can be further split into smaller VUs, for example, as follows:

- VU_WEB_USER can be split into 2 VUs each containing Web Server and one of the other modules.

- VU_PSTN can be split into 3 VUs, one for each module.

- VU_INT can be split into 2 VUs each containing Web Server and one of the other modules.

- VU_TERMINAL_n can be split into 2 VUs, one for each module.


22

- VU_CORE can be split into 3 VUs, one for each module.

- VU_INTERNAL_n can be split into 2 VUs each containing Web Server and one of the other modules.

A VU in the customer network is recommended if:

- Local (in the customer network) gateways retrieve prompts from local servers (MRS).

- Recordings, for example voice mail messages are saved locally.

For the above setup the recommended minimum number of servers is five. Failover servers must be added to this number. Failover servers do not have to be dedicated for a particular system, for example a pool of production servers can target a single failover server. How many production servers a failover server serves is based on risk analysis and is a business decision. The recommended five servers are:

- Management server in the management network.

- SAP Contact Center Core Server in the core network.

- SAP Contact Center Database server in the core network.

- SAP Contact Center Access Server in the access network

- SAP Contact Center DMZ Server in the DMZ network.

In an in-house setup, the network structure may be reduced as much as to one network containing all VUs or to two networks if Internet Chat Client are used. In the latter case, it is strongly advised that VU_DMZ reside in a DMZ network.

2.4 Interconnecting SAP Contact Center systems

SAP Contact Center systems can be interconnected using SIP trunks, that is, by configuring a counterpart SIP Bridge as a local SIP gateway in each of the systems. In versions before SAP Contact Center 7 this was done using the Federation Bridge (FBR).

CEM/CD

SBR

MRS MRSCDT CDT

CEM/CD

Voice Voice

Control

Control

Control

Control

Control

SAP Contact

Center 1

SAP Contact

Center 2

Intermediate

network

SBR

Voice /RTP

Figure 10. Connecting together two SAP Contact Center systems.

ENVIRONMANTAL AND FACILITY RECOMMENDATIONS

23

3 Environmental and facility recommendations

Suitable facilities assist in successful service management and operation and provide means for successful business. Facility recommendations aim to improve physical security and high availability. Facilities may be:

- run and owned by an enterprise or a service provider

- rented

- outsourced

To outsource the hosting of networks and servers not only saves one from the maintenance burden but may also significantly increase available expertise regarding the outsourced parts and enables the outsourcer to concentrate the efforts on SAP Contact Center operations.

3.1 Physical security

The purpose of security is to protect the personnel and assets and keep the business running smoothly. Physical security risk analysis and business impact assessment taking all possible physical threats into count is needed to implement security efficiently. All threats should be covered but the security measures should not be exaggerated. Below are examples of some physical security threats:

- Emergencies - Fire and smoke contaminants

- Building collapse or explosion

- Utility loss (electrical power, air conditioning, heating, cooling)

- Water damage (pipe breakage)

- Release of toxic material

- Natural disasters - Earth movement (such as earthquakes and mudslides)

- Storm damage (such as snow, ice and floods)

- Human intervention - Sabotage - Vandalism - War - Strikes

In general the following should be implemented:

- Walls (from the floor to the ceiling), floors, ceilings and doors have acceptable fire and strength ratings. Windows are normally not acceptable. Doors must resist forcible entry.

- no nearby water pipes and shutoff valve locations are known and accessible

- passage control with audit trails

- intrusion detection and alarm

- fire detection, fire alarm and fire extinguishing

Emergency procedures should be implemented and practiced, such as:


24

- Emergency system shut down

- Evacuation

- Periodic equipment and system tests

3.2 High availability

In order to offer high availability services, proper facilities providing the demanded supply and connectivity, protection against incidents and meaningful maintenance are needed.

3.2.1 Power supply

Power supply should always pass through UPS devices. In an online UPS the primary power source is a UPS battery. Online UPS devices provide galvanic isolation from the supplying electricity network and prevent undesirable current loops between devices connected to different switchgears. An online UPS is very similar to the least expensive standby UPS in that it has the same two power sources and a transfer switch that selects between them. It is the exact opposite from the standby UPS in that there is no transfer time in the event of a power failure and it efficiently filters off peaks and noise coming from the wall because those affect only the battery charger and not the inverter supplying the output power. Power failures in the power distribution network are instantly covered by UPS devices. In a power failure situation UPS devices are able to supply power for short times only, for a couple of hours, depending on the UPS capacity and the power consumption. Generators are needed to protect against power failures that last longer than the UPS is able to supply power. UPS devices cover easily the time it takes for generators to start.

3.2.2 HVAC

HVAC stands for heating, ventilation and air conditioning. HAVC is needed to keep humidity and temperature at acceptable levels, which are important parameters for electronic equipment. Electronic components are designed to operate at some specified temperatures at which specified tolerances are valid. Increasing temperature usually decreases electrical resistances and specified tolerances ceases to apply and eventually the functionality becomes undefined. Anti-static flooring is used to prevent static electricity and high voltage static electricity shocks from breaking electrical circuits. Increased humidity leads to increased electrical conductivity in the air and prevents static electricity but too high humidity leads to corrosion of leads of electrical components. HVAC should be arranged so that it is tolerant to failure of one single HVAC system.

3.2.3 Utilities

Utilities that ease management and maintenance are appropriate equipment shelves and cable routes. Rack cabinets are excellent for installation of rack servers and network devices. Devices should be easy to install, recognize and remove. Well-defined cable routes allow for easily adding required cabling and for removing unnecessary cabling.

3.2.4 Connectivity

Cable routes to the data center premises should be investigated. There should be at least two totally separate routes entering the building on different walls. The separation of routes should remain inside the building as close to the data center as possible. Alternate routes protect against failures on one of the routes. Such failures could be caused for example by fire or by a digger breaking the cable miles away.


25

3.2.5 Sites

Multiple sites provide continuity guaranties in case of major incidents such as fires and total loss of connectivity despite of alternate routes. In some cases alternate sites are required by law. The same recommendations are valid for each site. Distances between sites should guarantee adequate separation and independency of common data and power supply network nodes. This should be verified with the local power supply operator and telco. In general, the distance should be at least 15 km. Sites should be connected to each other with dual links backing up each other. These links and cable routes should be all the way separate from each other. Typically IP and FC (Fibre Channel) connectivity is required between sites, FC for connecting storage systems and IP for all the remaining traffic. IP and FC connections can be carried over a single mode fiber pair by multiplexing different wavelengths or colors to the same fiber pair. A third inter-site connection based on different technology such as SDH (synchronous digital hierarchy) is recommendable for cluster heartbeat control traffic. Inter-site fiber connections are typically 1 Gbit/s and for a third heartbeat connection 2 Mbit/s should be sufficient. Multi-site landscape enables also partial service distribution. For example a customer setup can have PSTN gateways in more than one site which can provide PSTN connectivity to more than one telephone exchange.

SERVER HARDWARE, OPERATING SYSTEMS AND SOFTWARE

26

4 Server hardware, operating systems and software

SAP Contact Center servers refer to the server hardware running the SAP Contact Center components. Basically any industry standard x86 and x64 servers are capable of running a SAP Contact Center system. Selecting specific hardware is a result of several aspects and is decided case-by-case. This chapter aims to give some guidelines for deciding on the appropriate hardware.

4.1 Servers

Prerequisites for the server configuration are:

- Site and network topology

- Capacity demands in terms of virtual units and/or modules

- Availability demands

- Facility demands

Site and network topology together with capacity demands prescribes the number of servers in the basic set and their specifications. Capacity refers to the number of virtual units and/or modules required.

Availability demands add failover servers to the number of servers in the basic setup.

Facility demands states the physical shape of the servers, such as tower, rack mounted or blade servers.

4.1.1 Number of servers

The number of servers depends, in most cases on network topology, availability demands and security issues but as the setups get bigger, also on performance issues. The SAP Contact Center system is modular and easy to scale up with increasing load. If performance at some point of time threatens to be a problem, it can be circumvented by adding respective virtual units on existing servers or on new servers.

It is a good idea to start designing the network layout properly and recognizing the network location of involved SAP Contact Center components. For example, in an in-house setup or demonstration system, there might be only one core network, the enterprise LAN, and thus all components would reside there. In such a case, the minimum number of servers is two, one running the databases and one running the other components. This setup is suitable only for systems with light load and low availability requirements.

Site and network topology affects the number of servers required. Different network zones, such as DMZ and/or management network, require separate servers. Site and network topology might also place requirements for additional network interfaces on multi homed servers.

Capacity demands affect the number of virtual units required and thus may also affect the number of servers. Restrictions of virtual unit capacity do not necessarily correlate to available CPU or I/O power. They can be due to the number of threads a process may create or some other operating system or software-specific features. One server may thus run several, even similar, virtual units. Chapter 14, Sizing, covers this topic in more detail.

Availability demands determine precautions for eventual fault incidences and procedures for maintenance tasks. Precautions for fault incidences are failover mechanisms. Failover can be configured in the following ways:

- Manual failover


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- Automatic failover

- Failover to other active SAP Contact Center servers

- Failover to inactive dedicated failover servers

Manual and automatic failover is covered in chapter 12, Availability and maintenance. This topic may affect the number of required servers. With manual failover, an operator can choose the most suitable one of the available failover destinations. With automatic failover, capacity must be prepared in advance at one or more specific failover destinations.

If the set of active SAP Contact Center servers are only moderately utilized and the capacity budget allows it, failover destinations may be configured within the set without using dedicated standby servers for failover. If utilization increases over time, the setup can be reconfigured with one or more dedicated standby failover servers.

When maintenance tasks can be performed outside office hours there is no 24/7 demand and there is no demand for additional failover destinations for maintenance reasons. If it is not possible to perform maintenance outside office hours because of a 24/7 demand, failover destinations must be available to enable uninterrupted service during maintenance.

4.1.2 Type of servers

SAP Contact Center runs on industry standard x86 and x64 based server hardware. There are several selection criteria for the servers and the emphasis may vary from case to case. The most essential criteria are described below.

4.1.2.1 Storage and application servers

From a functional point of view two types of servers are used:

- Storage servers with significant file I/O, storage capacity and backup demands

- Application servers with performance focus on CPU and networking

Storage servers refer to SAP Contact Center (SQL) database servers and file servers. SAP Contact Center database servers are used for storing, for example, system configuration, user accounts and call detail records (CDR). File servers are used for storing, for example, prompts, voice mail messages, recordings and attachments. Storage servers contain both static data (configuration and user data) and dynamic accounting data (CDR).

The static data is crucial to the operation of SAP Contact Center and therefore attention must be paid to its availability. It is recommended that static data is kept on clustered servers and that the data is regularly backed up.

The dynamic data is not crucial to the ongoing operation of SAP Contact Center, but its value is often essential because of billing, production control, service control or other business related issues and may thus be vital to the service provider and/or to the customer. It is recommended that dynamic data is kept on clustered servers and that the data is regularly backed up.


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Application servers run various SAP Contact Center virtual units. They retrieve process and store data between users, other virtual units and data storages. Application servers are replaceable in the sense that they do not contain any crucial data and their assignments can therefore be overtaken by other servers.

Performance characteristics have emphasis on file I/0 and storage capacity for storage servers and network I/0 and CPU for application servers.

4.1.2.2 Server chassis and operability

It might seem that there is no, or very little, importance in what type of server chassis is selected. As noticed earlier, this also may vary from case to case and it may have considerable importance in some cases. Server chassis alternatives are:

- Tower

- Rack

- Blade

Tower servers are suitable for in-house setups, if the existing facilities do not require any other type of servers to be selected. Tower servers often have the space for sufficient RAID (redundant array of inexpensive disks) disks, integrated sophisticated RAID controllers and enough slots for possible additional RAID controllers and network interface cards. The drawbacks of tower servers compared to the others are:

- Big space requirements.

- Lack of built-in KVM (keyboard, video, mouse) switches/multiplexers.

- Discrete power and network cabling.

Rack servers are designed to be mounted in a server cabinet. The advantages of using rack servers are:

- More effective space usage

- Better order and control of servers and cables

- Possibility to arrange and adjust power and cooling on a per cabinet basis.

- Some rack servers contain built-in KVM switches enabling a group of servers to be operated from one console.

Rack servers come in different sizes or heights. The height of rack servers is measured in units (U) where one U is the minimum height of a device that can be installed in a cabinet. A cabinet may contain for example 40 or 42 U. One U servers are usually suitable for application servers whereas, storage servers require more space for disks and possible additional network and/or RAID boards. Rack mount kits are available for some tower servers.

Attention should be paid to the cooling of rack mounted servers. Cooled air should flow through the cabinet, for example from the bottom to the top.

Rack-mounted servers are a good choice for enterprises and service providers running several servers.


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Blade servers are electronics boards that are installed to a blade chassis. The blade chassis is installed in a similar cabinet as rack servers. The blade chassis provides power and required interfaces to the blade. Benefits of blade servers are:

- The most effective space usage

- Integrated cabling, power, network and storage

- In some cases, integrated LAN switches

- Integrated KVM switches

- Improved reliability due to the integrations

- Possibility to configure hot standby blades

Regardless of the selected chassis type, the following features are recommended:

- Dual power supplies for increased availability

- Dual fans for increased availability

- Management, such as HP ILO and/or SNMP for retrieving notifications of possible failures or arising problems.

- Separate physical network interfaces for each network (core, access, management) the server connects to.


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4.1.2.3 Server specifications

These server specifications are indicative. The recommended specifications are based on experiences from existing installations in service provider and in-house setups. Below are the minimum and recommended server specifications.

Feature

SA

P C

Ctr

light

App

licatio

n

serv

er

SA

P C

Ctr

App

licatio

n

serv

er

SA

P C

Ctr

Sto

rage

Serv

er,

SQ

L

SA

P C

Ctr

Sto

rage

Serv

er,

File

Serv

er

MIN REC MIN REC MIN REC MIN REC

CPU speed 1 GHz > 1 GHz 1 GHz >= 2 GHz 2 GHz > 2 GHz 1 GHz >= 2 GHz

Number of CPUs & cores together

1 2 2 2 - 4 1 2 - 4 1 >=2

RAM 1 GB 2 - 4 GB 1 GB 2 - 8 GB 4 GB 4 – 32

GB 1 GB >= 2 GB

Network interface 100

Base-T 1000

Base-T 100

Base-T 1000

Base-T 100

Base-T 1000

Base-T 100

Base-T 1000

Base-T

Number of network interfaces

1 1 1 1 - 2 1 1 - 3 1 1 - 3

Operating system on local disks

Yes Yes Yes - Yes Yes Yes Yes

Data on local disks Yes Yes Yes - Yes No Yes No

Operating system on SAN

- - - Yes - No - No

Data on SAN - - - Yes - Yes - Yes

A SAP Contact Center light application server is running only few SAP Contact Center components or is very lightly utilized, for example, a demo system.

The design aspects of the entirety may lead to standardizing application server configurations and to thus make the hardware interchangeable, so that, for example, any SAP Contact Center light application server can be assigned the tasks of any other SAP Contact Center light application server without any need to upgrade the hardware. An arrangement including some minor additional investments in hardware, such as RAM, might be required. Those investments facilitate smoother maintenance practices and are quickly paid back.

From a dimensioning perspective, it is recommended to allocate one dedicated CPU for the OS on servers that are expected to have high utilization even if the CPU control mechanisms are not available. CPU cores available to SQL Server instances can be configured and it is recommended to configure each SQL server with at least one dedicated CPU core.

SQL Servers benefit from all available RAM. In a multi-instance installation, the amount of RAM available for each instance can be configured. Especially in reporting and analysis, but not limited to these, the performance is improved by increasing available RAM.


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The number of network interfaces depends on several things:

- Network topology: Dual-hosted servers require at least two network interfaces. A server can be connected, for example, to an access network and to a management network or to an access network and to a core network.

- High availability: Network teaming (a dual connection providing fault tolerance) requires at least two network interfaces.

- Clustering: It is recommended that at least three network connections are made available for cluster control and heartbeat traffic and that at least one of them is dedicated for this purpose.

The best location of the operating system and the data, which would be either local or SAN disks, is affected by the intended maintenance procedures:

- Using servers, especially blade servers, retrieving the operating system from SAN and storing data to SAN and not having any local disks, makes the servers “dummy” electronics boards with no identity. This enables fast and easy reassignments of servers to different tasks and can be useful, for example, during version updates and when applying patches.

- All servers should have at least a mirrored (RAID-1) disk configuration. In some cases, for example, with DMZ servers, it might be more reasonable to use local disks.

- Cluster servers should always have local disks for the operating system and SAN disks for data to ensure proper cluster control and data availability at all times.

The hyphen “-“ in the table indicates a neutral attitude. The decision is usually made based on existing possibilities and on design aspects of the entirety.

See appendix A for sample SAP Contact Center Servers.


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4.2 Operating systems

Supported operating Systems for SAP Contact Center servers are English versions of Windows Server 2008, Windows Server 2008 R2 (both referred to as Windows 2008 in this context, if not explicitly mentioned otherwise) and Windows Server 2012, all with the latest service packs. Supported editions are Standard and Enterprise. Below are the most significant features of the editions and the differences between them in relation to SAP Contact Center.

Feature

Win

dow

s 2

00

8 x

64

Sta

ndard

ed

itio

n

Win

dow

s 2

00

8 x

64

Ente

rprise e

ditio

n

Win

dow

s 2

01

2

Sta

ndard

ed

itio

n

Max memory 32 GB 2 TB 4 TB

x64 sockets 4 8 64

Cluster service No Yes Yes

Standard editions are recommended for SAP Contact Center application servers. Enterprise edition is recommended for SAP Contact Center storage servers because of the larger amount of maximum memory and the clustering capability. If clustering is not required for file servers, standard edition can be used. It is recommended to always apply the latest services packs provided by Microsoft.

4.3 Software

Software refers to third party software required by SAP Contact Center, such as SQL Server. Essential software and/or operating system services for SAP Contact Center are:

- Windows Server Active Directory

- Microsoft Internet Information Server

- Microsoft SQL Server

- Microsoft Certificate Services (optional)

- Windows DCHP Server (optional)

- A TFTP Server (optional)

- A syslog server (optional)

SAP Contact Center servers are usually added to a Windows domain. Some exceptions exist, for example, a SAP Contact Center CS Server installed in a DMZ zone does not typically belong to any domain. Windows Server Active Directory is used for maintaining Windows user and computer accounts in that domain. Windows user accounts are created for SAP Contact Center administrators, operators and services.


33

Microsoft Internet Information Server is used for running SAP Contact Center web services, such as the CDT and Administrator interfaces.

Microsoft SQL Server is the database system used by SAP Contact Center. See section 4.3.1, Microsoft SQL Server, for more information about Microsoft SQL Server.

Microsoft Certificate Services (CA) can be used to create self-granted server certificates for encrypted SSL connections. Parties (such as hosts and services) connecting to services using self-granted certificates must recognize the issuing CA as a trusted root.

Windows DHCP Server can be used to provide gateways, IP desk phones and other equipment residing in the server network with IP-addresses and additional information, such as boot files, configuration files and configuration information.

A TFTP server (any available) can be configured in the DHCP information as a destination where IP Desk Phones can find additional configuration information. Configuration information can also be stored from a device to a TFTP server for example as a backup.

A syslog server can be used to log messages from devices such as IP Desk Phones and gateways. Most devices provide alternative log levels to avoid storing uninteresting information. A syslog server with the ability to filter syslog events and forward selected ones via e-mail and/or notifying of essential events via SNMP (simple network management protocol) is recommended.


34

4.3.1 Microsoft SQL Server

Microsoft SQL Server comes in different editions of which SQL Server 2008 Standard and Enterprise editions and SQL Server 2012 Standard editions and 64-bit systems are supported.

Below are the most important features of the editions and differences between them in relation to SAP Contact Center.

Feature

SQ

L S

erv

er

20

08

R2 S

tand

ard

editio

n

SQ

L S

erv

er

20

08

R2 E

nte

rpri

se

editio

n

SQ

L S

erv

er

20

12

Sta

ndard

ed

itio

n

Max number of CPUs 4 8 ¤lesser of 4 sockets or 16 cores

Max RAM 64 GB 2 TB 64 GB

Database size 524 PB 524 PB 524 PB

Database mirroring Yes (single thread)

Yes Yes

Failover clustering Yes Yes Yes

SQL Servers running the reporting databases should have the SQL Server options Analysis Services and Reporting Services installed.

4.3.2 Microsoft Internet Information Server

Microsoft Internet Information Server (IIS) is used by SAP Contact Center to provide user interfaces to CDT and to administrative tools. IIS is included with the Windows Server but not installed by default and is an option that needs to be selected manually.

If e-mail notifications are needed, for example, from voice mails and SMS messages, SMTP (simple mail transfer protocol) needs to be installed. SMTP is included with IIS, but not installed by default and is an option that needs to be selected manually.

One IIS server can contain several web sites, one per each installed virtual unit, for example, VU_WEB_USER. Each web site and thus virtual unit can and preferably should be assigned a unique IP address. Backup instances of each web site should share that same unique IP address.

4.3.3 Certificates

SAP Contact Center uses SSL server certificates to authenticate SAP Contact Center servers and to encrypt traffic between servers and clients. Servers refer to SAP Contact Center components listening to connection attempts. Clients refer to SAP Contact Center components initiating connections. Both servers and clients can be SAP Contact Center service components. Authentication succeeds when all of the following are true:


35

- The URL connected to matches the name the certificate is issued to.

- The certificate date is valid.

- The issuer of the certificate is trusted by the client.

Certificates can be obtained from any certification authority (CA) trusted by the client. Windows Server contains by default several trusted certification authority (trusted roots) certificates. Trusted CAs can be added by adding their certificates among the trusted certification authorities.

For internal usage, for example, for authentication and encryption inside the core or access network, the certification authority services included with Windows Server can be used. They are not installed by default and need to be selected manually. For self-granted certificates, the certificate of the issuer needs to be distributed to the clients, usually manually.

For other usage certificates issued by public certificate authorities are recommended to avoid massive distribution of CA certificates to numerous clients. Public certificate authorities are, for example, VeriSign and Thawte.

GATEWAYS AND SIP TRUNKS

36

5 Gateways and SIP trunks

Gateways connect PRI-lines from PSTN networks to IP networks and enable calls to pass from one to the other. SIP trunks do the same except for that they are already IP so no conversion is needed on network level. However, some conversion on SIP protocol level might be needed to make the two SIP implementations work together. This is done by a Session Border Controller that usually also provides security features and sometimes even codec translation (transcoding).

In in-house cases gateways are installed in the customer LAN. In service provider cases, they are typically installed in the service provider network but they can also be distributed over the customer LAN or over the service provider network and customer LAN. The same applies to SIP trunks.

SAP Contact Center uses primarily SIP as the control protocol toward gateways and SIP trunks. The H.323 protocol is also supported but no new features are implemented upon that protocol in SAP Contact Center.

SIP Bridges and H.323 Bridges are call control components interfacing towards gateways and SIP trunks in SAP Contact Center.

Finding suitable locations for gateways and SIP trunks is an important step in designing each SAP Contact Center landscape. Affecting factors are:

- Cost of PRI-lines, gateways, SIP trunks and SBCs

- Cost of sufficient bandwidth from gateways and SBCs to voice endpoints (LAN & WAN)

- Preferred telephone numbering, regional or nationwide (e.g. area codes)

Because of the real-time requirement of voice streams, the networks ability to carry them is considered in landscape design. To be able to optimize the network’s ability to carry voice, it is essential to understand the possible voice stream paths and to recognize the possible endpoints. Gateways and SBCs are voice stream endpoints in external calls. The other voice stream endpoint is either an immediate endpoint such as:

- IP desk phone

- CDT

- IVR

- Voice Mail

- In some special cases, another gateway

Or, it can be an intermediate endpoint, such as the SAP Contact Center MRS (media routing server) component, which forwards the voice stream to a next endpoint.

MRS may also be an immediate voice stream endpoint depending on its function. MRS is used to:

- Play prompts (immediate)

- Record voice streams (immediate)

- Relay voice streams (intermediate)

- NAT fixup (intermediate)

- Encryption endpoint (immediate or intermediate)

5.1 Distributing gateways and SIP trunks

Distributing gateways and SIP trunks over headquarters and branch offices may provide local telephone numbering and may also significantly reduce the required WAN bandwidth between the sites and the service provider network.


37

Distributing gateways may at the same time increase the number of required gateway capacity or SIP trunks.

For example a company has two offices and a demand for a maximum of 30 simultaneous calls. If nationwide telephone numbering is used, the company can manage with one gateway and one E1 line in the service center network. Less than a 2 Mbit/s data link is required but smaller data links with sufficient capacity are often not available.

PSTN

Site 1

LANClient

Site 2

LANClientEnterprise

Network

Service

Provider

E1

2 Mbit/s2 Mbit/s

Figure 11. Gateway located in service provider network

.

If regional telephone numbering is used at both offices, two gateways and two E1 lines are required. The narrower data links are sufficient for Control Protocols and UI traffic (CDT). If prompts are played often 1 Mbit/s links should be used instead, or MRS at each site should be available to provide prompts locally.

PSTN

Site 1

LANClient

Site 2

LANClient

Enterprise

Network

Service

ProviderE1 E1

512 kbit/s 512 kbit/s

Figure 12. Gateways distributed to each customer office.

Back-up capacity is often wanted, which also comes in multiples of E1/T1/J1 lines and gateways. Fault tolerance might be easier to arrange using SIP trunks because SIP trunks are often provided from clusters. Still, the fault tolerance is probably sold as an additional service and fault tolerant underlying connections may also be needed.

Combining nationwide telephone numbering with gateways and SIP trunks distributed to both offices can provide back-up capacity for one PSTN link if sufficient IP bandwidth is available for carrying voice between the offices.

Another level of back-up capacity can be arranged by locating both gateways in the service provider network and by ordering the E1/T1/J1 lines to different telephone exchanges in the PSTN. This presumes that the PSTN cabling routes are sufficiently separated all the way to the gateways in order to eliminate single points of failure. This also usually presumes that nationwide numbering or the same regional numbering is used.

5.2 Connecting to a PBX

Gateways can also be used to interconnect SAP Contact Center systems with existing private branch exchanges (PBX) or PBX networks to enable calls to pass from one to the other. This can be done, for example, to implement the SAP Contact Center deployment in phases. Technical connections must be done, telephone number ranges must be matched and routing rules configured on both sides.

For example the company A has a telephone number range of 250 1300 – 250 1799. The SAP Contact Center migration is not yet completed and 300 subscriptions are created in SAP Contact Center while 200 still exist on the traditional PBX.

SAP Contact Center subscriptions are assigned the numbers 250 1300 – 250 1599 and the numbers 250 1600 – 250 1799 are still in the PBX.

To enable calls between all employees, a gateway is installed to connect the SAP Contact Center system to the PBX. The E1/T1/J1 port of the gateway is used to connect to the PBX and as normally, the Ethernet port is


38

used to connect to the SAP Contact Center system.

The PBX is configured to route all, except the numbers 250 1600 – 250 1799, to the port where the gateway is connected.

The gateway is configured to route the numbers 250 1600 – 250 1799 to the port where the PBX is connected.

PBX

PSTN

SAP CCtr System

250 1600-

250 1799

All but

250 1600-

250 1799

250 1300-

250 1799

All but

250 1300-

250 1799

Figure 13. Connecting a gateway to a PBX.

Another way to do the interconnection is showed in figure 14, where the gateway is connected between the PSTN and the PBX. This setup requires the gateway that has at least two E1/T1/J1 ports and the capability to route configured number ranges as showed in figure 14. Usually this setup is reasonable when only one E1/T1/J1 connection is needed to connect to the PSTN.

PBX

PSTN

SAP CCtr System

All but

250 1600-

250 1799

All but

250 1300-

250 1799

250 1600-

250 1799

250 1300-

250 1599

Figure 14. Connecting a gateway between the PSTN and a PBX.


39

5.3 Miscellaneous settings

Gateways are usually configured by default to retrieve the synchronization clock signal from the PSTN network. Gateways are typically configured as slaves and the telephone exchange, to which the gateway is connected, is configured as a master. Connecting to a PBX involves explicitly setting either the PBX or the gateway as a master and the other as a slave. Master is also referred to as NT (network terminal) and slave as TE (terminal equipment).

ISDN is sometimes referred to as DSS1 (digital signaling system 1). The protocol used on the PSTN side should be ISDN S2. R2 is not supported.

Voice codecs supported by SAP Contact Center are G.711 and G.729. The cloud edition supports only G.711.

ISDN protocols refers to N-ISDN including Q.931 and Q.921.

5.4 Cisco gateways

SAP Contact Center supports Cisco multiservice Modular Access routers configured to VoIP gateways using High Density Voice Network Modules. These gateways differ essentially from the other supported gateways in the way they are built and in that they simultaneously serve as routers. Other supported gateways include also modular models but they are less complex.

Such a Cisco gateway is comprised by:

- A multiservice Modular Access Router

- One or more High Density Voice (HDV) Network Modules (NM)

- One or more Voice/WAN Interface Cards (VWIC)

- One or more Packet Voice DSP Modules (PDVM)

Each HDV Network module has one VWIC slot. The VWIC provides the interface to the PSTN, E1, T1 or J1. VWICs are available with one or two T1/E1/J1 ports.

Up to 5 PDVMs can be installed on each HDV Network Module. The amount of required PDVMs depends on the amount of simultaneous calls and codec being used.

For more information, see www.cisco.com.

Supported and recommended hardware, operating systems and software can be found in the infrastructure compatibility list (ICL) in the support portal.

http://www.cisco.com/

DATA CENTER LAN

40

6 Data center LAN

Data center LAN refers to the LAN, where the SAP Contact Center Servers reside and where the SAP Contact Center services are produced by a service provider or by an in house operator. The LAN consists basically of Ethernet Switches connecting servers and network devices together over LAN cables, such as CAT5/6, and IP routers connecting the LAN to the outside world over WAN links. Recommended networks are 1000 Base-T switched networks.

SAP Contact Center service availability is extremely important to the customers and to the users. It appears far more critical than traditional IT systems like e-mail and World Wide Web. The most important features of the data center LAN are:

- Performance

- Availability

The data center LAN is crucial to the SAP Contact Center service availability as the SAP Contact Center service availability cannot exceed the data center LAN availability. The performance of the data center LAN is vital to the SAP Contact Center service availability because only minor and occasional voice distortions are tolerated, if any.

6.1 Performance

Different traffic shapes apply to different network boundaries. Between a management network and a core network, there is management traffic, such as SNMP traffic and traffic related to configuration tasks. Between a core network and an access network there are mainly database queries and SAP Contact Center Control Traffic. Unlike voice streams, these do not have real time demands.

Voice streams are typically carried from voice endpoints in the access networks over service and access links to voice endpoints in the customer LAN. Voice endpoints are any immediate or intermediate devices or services transmitting or receiving voice, such as CDTs, IP desk phones, VoIP gateways, routers and MRSs.

It is recommended to keep the network layout as straight-forward as possible by minimizing the network distance between endpoints. Doing this provides more robustness against voice distortions due to increasing delay caused by increasing overall utilization. This also minimizes the number of devices a particular service depends on and minimizes the points of failure. Increased overall utilization can be caused, for example, by new end users and customers, but also by poor configuration allowing or generating unnecessary traffic.

The above can be applied the other way around too. In a data center access network serving several customers, minimizing the network distance between service endpoints may decrease the number of services that depend on any particular device and can therefore be considered as a kind of segmentation into smaller failure domains.

6.1.1 Minimizing network distances

In a network based on hubs directing all traffic to every port and thus all over the LAN, the maximum nominal capacity equals the maximum peak performance, for example, in a 100 Base-T network the aggregate momentary throughput cannot exceed 100 Mbit/s.

However, switched networks allow for traffic isolation between parties and traffic is not unnecessarily propagated all over the network. Therefore in a switched network with the nominal capacity of 100 Mbit/s, two or more simultaneous fully utilized 100 Mbit/s connections may exist.

Switched networks are strongly recommended for SAP Contact Center data center networks as well as customer LANs. Small SOHO (small office home office) sites with only a few hosts and modestly utilized networks are an exception with less strict recommendations.

The maximum aggregate performance of a switched network depends on the network topology and on the performance of the network devices themselves. The absolute maximum capacity of any link and switch port is

DATA CENTER LAN

41

its nominal speed. Two switches connected together over a 100 Mbit/s link cannot carry more than 100 Mbit/s data between them although the total demand from other ports would exceed this as depicted below.

A B C D E F G HSwitch 1


100 Mbit/s

40

Mb

it/s

40

Mb

it/s

40

Mb

it/s

40

Mb

it/s

40

Mb

it/s

40

Mb

it/s

Demand 120 Mbit/s

CONGESTION

Figure 15. Network congestion/overload on interconnecting link between switches.

Devices contributing to one and the same service should be located close by in the network to minimize the network distances and thus to optimize the network performance as figure 16 shows..



100 Mbit/s

40

Mb

it/s

40

Mb

it/s

40

Mb

it/s

40

Mb

it/s

40

Mb

it/s

Demand 80 Mbit/s

NO CONGESTIO

N

40

Mb

it/s

Figure 16. Network distance between related services is minimized to optimize performance. The host or segment connected to switch 1, port F, has been moved to switch 2, port H.

One solution is to use 1000 Base-T links between switches, but it is still recommended to minimize the network distance between related devices and services. Every additional hop introduces a potential delay and a potential point of failure.

Based on this, it seems that in a switched network the aggregate capacity is a multiplier n times the nominal network capacity, where the multiplier n depends on the network topology and the capability and speed of the switches to queue and forward traffic. However, queuing traffic introduces delivery delays eventually distorting the voice quality.

Service segmentation provides some certainty of service availability and service infrastructure should be divided into self-sufficient parts independent on incidents in other parts. Therefore it is recommended to have another access network in advance before the previous is utilized to its reasonable extents.

6.1.2 LAN capacity

For data center LANs, 1000 Base-T (1 Gbit/s) is recommended for core networks. A core network can serve more than one access network, either physical or logical. The capacity demands of the access networks relates to the aggregated capacity of the service links or access links. (See chapter 1, Introduction for a description of

DATA CENTER LAN

42

core networks, access networks, service links and access links).

Assuming that, in a pure SAP Contact Center environment:

an average Ethernet network utilization of 40% is a reasonable maximum limit

80% of the traffic would be destined over access links and 20% to and from the core network

It would occur that a 100 Base-T access network would be capable of serving approximately

100 Mbit/s x 0,4 x 0,8 = 32 Mbit/s access and service links.

In a switched, well-structured network this might apply to each one switch in the network. The network utilization varies over time as the number of simultaneous calls and directory queries varies. Unlike traditional IT systems like e-mail, where it is possible to wait some seconds in a congestion situation, a SAP Contact Center system must be designed to carry-real time voice at any moment as dimensioned. Average loads do not count and dimensioning must apply to peak loads.

6.1.3 VLAN

Virtual LANs (VLANs) provide broadcast filtering, security, address summarization and traffic flow management. VLANs can be used to provide the segmentation services traditionally provided by routers in LAN configurations, for example, to split a large access network into segments and by doing this, increasing manageability and security. By definition, switches may not bridge IP traffic between VLANs because it would violate the integrity of the VLAN broadcast domain.

VLANs have the same attributes as physical LANs but they allow for end stations to be grouped together even if they are not on the same LAN segment. In a legacy network, end stations are assigned to networks based on geographical location. Using VLANs, networks can be logically grouped without physical LAN topology restrictions.

Two kinds of VLANs exist. One is based on the protocol IEEE 802.1Q, where Ethernet frames are tagged with VLAN information allowing for VLAN multiplexing over trunk lines. These VLANs are suitable for reaching logical core, management and access networks over multiple sites. Each VLAN appears as one and the same network regardless of its physical location.

The other kind of VLANs are port-based VLANs. With port-based VLANs two or more switch ports are assigned a VLAN identifier which groups the ports together to a port-based VLAN. Traffic cannot flow between ports belonging to different VLANs without passing through a VLAN router. Multi-VLAN ports may be configured to, for example, provide management or database services from a single VLAN to multiple other VLANs.

6.2 Availability

The data center LAN availability focuses on keeping the network serve its purpose by avoiding unnecessary or unwarranted traffic and by preparing for failures. Together with diligent network management, operation and monitoring, access control and fault tolerance are central elements of high availability. Prioritizing may also be considered a protection mechanism with similarities to access control.

6.2.1 Access control

Access control is an enforcement method allowing only relevant traffic. Unwarranted traffic is rejected at outer network boundaries by firewalls but there might be unnecessary traffic inside generated by servers and network devices. Switches with ACL (access list) capabilities can be used to constrain the inside distribution of unnecessary traffic in the network.

See chapter 11, Security, for access control at outer network boundaries as protection against external threats. In this context, access control is considered as an enabler for network robustness which is done with access

DATA CENTER LAN

43

lists on switches. Access control can be based on, for example, any of the following:

- Source IP address or address range

- Destination IP address or address range

- Source port number or port number range

- Destination port number or port number range

- Protocol

- Connection direction for TCP protocols

The data center LAN may be segmented into different networks to obtain more granular control over it and the network traffic in it. Such segments may be, for example, core, access and management networks where boundary controls are implemented and/or virtual LANs (VLAN) assigned to a customer or a group of customers.

Access controls inside a segment, or even inside a data center LAN, can be implemented with switches but on the outside boundary towards a customer or another organization, more sophisticated firewalls are recommended.

Access control contributes to availability and high quality of service. It may constrain the distribution of unnecessary or even malicious traffic caused by:

- Accidental improper configuration

- Improper functionality caused by, for example, software bugs

- DoS (denial of service) attacks, malicious and other

- Faulty devices

Access control should be carefully planned and clear benefits and objectives should be recognized, such as, allowing specified traffic shapes or protecting organization limits. Good options are allowing only voice streams and control protocols to voice endpoints or allowing only traffic to and from a specific organization. Access control should be kept as simple as possible and well documented.

6.2.2 Prioritizing

Prioritizing involves categorizing traffic into different traffic classes and to assign priorities to those classes. Categorization of traffic can mainly be based on the same factors as access control and it can also be based on a type of service identifier (ToS or ToS bit). Traffic with higher priority is passed through network devices, such as switches and routers, before traffic with lower priority. ToS bits are usually set by endpoint but it is also possible in some cases to set ToS bits on network devices on the transmission path.

In opposite to access control, which strictly allows or rejects traffic, prioritizing does not initially reject traffic but instead allows higher prioritized traffic pass before lower prioritized traffic. With increased utilization and congestion, prioritizing will eventually cause low priority traffic to be dropped and thus allow higher priority traffic to be carried over the network.

Prioritizing is a mechanism providing control over bandwidth usage. It does not provide means to counteract low bandwidth. Prioritizing may provide higher availability in the same cases as access control and it could also be seen as a performance factor.

6.2.3 Fault tolerance

Fault tolerance protects the service production against physical device and network failures by routing the traffic over an alternative path in case of failure of a link or network device. The fault tolerance degree of the network

DATA CENTER LAN

44

may vary. It may include the whole data center LAN, only the most critical parts of it or something in between.

The fault tolerance of the data center LAN is a part of the overall SAP Contact Center service fault tolerance and it relates to fault tolerance implemented by network topology designs, network hardware and network protocols.

6.2.3.1 Deciding on the fault tolerance degree

The fault tolerance degree is a business decision based on risk analyses and liabilities of service availability. Moreover, it is also associated with the reputation the of service provider wanting to provide outstanding services.

The following questions can be used when deciding on the degree of the fault tolerance:

- Are total (all services/customers) service downtimes allowable? If not, then the following can be used:

- - Independent service pools are required to constrain the service breaks. - Partially independent service pools sharing common clustered service pools are required - The service pools must contain comprehensive failover mechanisms.

- Is a couple of minutes of downtime allowed during a failover? If not, then the failover probability must be minimized by adding robustness to each component

Each step costs additionally and each incidence has its price, probability and estimated recurrence. However, the reasoning described below is difficult and laborious to use when drilling into a variety of details and equipment. Another thing is that the cost of an incidence is easily underestimated.

An incidence may involve:

- Interrupting ongoing tasks and thus delaying new business

- Working overtime

- Requiring third party services outside business hours

- Penalties to customers

- Reputation damage

To keep the reasoning simple, think if a particular incidence is allowed even once. If not, then counteract it. Otherwise follow-up the recurrence and reconsider the situation if needed.

In general, it is recommended that all simple fault tolerance measures are implemented, such as:

- Dual power supplies

- Dual cooling fans

The final outcome of the reasoning should be a fault tolerance plan or a risk chart showing the critical spots and outlining the steps of precaution.

6.2.3.2 Teaming

Teaming is a technique using two or more network cards to connect a server to the network. The team or the group of network cards appears as one logical network card in the operating system. The remaining network cards assume the traffic of the failed card, if one network card in the group fails. The virtual network card has

DATA CENTER LAN

45

one MAC address and one or more IP addresses just as real network cards do. Teamed network cards also share the network load increasing the available network bandwidth and providing load balancing.

6.3 Multiple Sites

SAP Contact Center services may be available from more than one real-time failover site. This is typically the case when the business grows to and it becomes too risky to rely on only one site, or when there are legislative demands of guaranteeing service availability from more than one site. Arranging with two sites provides for disaster tolerance and disaster recovery.

Basically, providing the SAP Contact Center services from two or more alternative sites requires:

- Alternative premises with far enough distance between them. The distance depends on the disaster prepared for. For protection against fire emergencies, collapsed buildings, power outages and data link outages, a suitable distance could be about 20 km or more. Power and data network structures should be discussed with respective providers before deciding alternative locations.

- Partially or fully duplicated production equipment, such as servers and gateways. It is possible to run only selected services with standby failover on remote sites.

- Connections to the PSTN from each site.

- Service links to each site.

- Duplicated connections between the sites.

- Common data storage, preferably a real-time mirrored SAN between the sites.

Obviously providing real time failover services from alternative sites is costly. However, the actual case might be that only a fragment of the customers demand this high availability and disaster tolerance. Establishing alternative production sites provides also more production capacity and preparing for alternative sites might be a good growth strategy from the very beginning. This reduces the risk of having too much of the service provider business on one site and reduces the initial costs by keeping premises and facilities a little bit smaller at the beginning.

The majority of multi-site concerns are exactly the same as with single sites because multi-sites are run with, for example, identical servers and data links. The points to focus on are:

- Common broadcast domain in all failover sites.

- Connecting sites together

- Data connectivity and routing

- Distributed real-time mirrored SAN

- Incoming call routing

- Arranging for cluster and HAC nodes in each site

6.3.1 Common broadcast domain

The Ethernet broadcast domain is the area or group of devices receiving Ethernet broadcast messages. The Ethernet addressing is based on MAC addresses, also known as hardware addresses. The address is a hexadecimal number unique to each network interface card.

Since MAC addresses are not divided into network and host portions, a host cannot determine from the MAC

DATA CENTER LAN

46

address of another host if that is on the same network or not.

To be able to address hosts on other networks, IP addresses are used. IP addresses contain a host portion and a network portion. Another host is in the same network if the senders and receivers network portion of the IP address are the same. Otherwise it is on a different network and will be addressed via a router.

Hosts and services are configured with IP addresses. For example, an IP desk phone is configured to find its registrar at the IP address 10.10.0.5.

The IP desk phone uses ARP (address resolution protocol) to determine the MAC address of the registrar by sending an ARP request containing the IP address 10.10.0.5 and the MAC address of the sender. ARP requests are sent with Ethernet broadcast addresses and received by every other host in that network. The host configured with the IP address 10.10.0.5 replies with an ARP reply containing its MAC address. This way, MAC addresses are changed between hosts and the rest of the communication continues using these MAC addresses. Hosts store MAC addresses in their ARP tables until they expire. Then they are requested for again when needed.

The SAP Contact Center high availability concept includes virtual IP addresses assigned to SAP Contact Center services. The virtual IP address hides the actual server or site from the user.

The SAP Contact Center high availability concept is based on virtual units having more than one instance sharing the same IP address and of which only one instance is active at a time. However, each instance has its own network interfaces and its own MAC addresses that must be resolvable by the router connecting to the customer.

Therefore, sites must be in the same broadcast domain and there must not be a routed connection between them.

6.3.2 Connecting sites together

IP and Fibre Channel links can be used to connect two sites together. Fibre Channel is a gigabit-speed network technology primarily used for storage networking. Here it is used to connect the SANs of the two sites together. IP is used for all the remaining traffic.

Single mode (SM) optical fibers are recommended as the physical link media between sites, because of their excellent ability to carry information over long distances without any repetition or other electronic intermediate devices constituting points of failure. One fiber link consists of two fiber strains or a fiber pair. For fault tolerance, two separately routed fiber pairs are used.

CWDM (coarse wavelength division multiplexing) is used to deploy different services such as IP and FC over a single fiber pair. CWDM is an optical technology for transmitting several channels, each in a separate wavelength or color, over the same fiber strand. Unlike DWDM (dense wavelength division multiplexing) which can transmit 32 or more channels on the same fiber, CWDM uses a more loose spacing between channels and is less expensive than DWDM. The International Telecommunication Union (ITU) has standardized a 20 nm channel spacing grid for use with CWDM with the wavelengths between 1310 nm and 1610 nm.

SM Fiber pair

(receiving &

transmitting)

Gray

Violet

Blue

Green

Yellow

Orange

Red

Brown

Gray

Violet

Blue

Green

Yellow

Orange

Red

Brown

Site 1 Site 2

DATA CENTER LAN

47

Figure 17. Multiplexing several channels over an optical fiber pair (CWDM).

Figure 17 shows two eight channel CWDM multiplexers connected over a SM fiber pair. Each channel can be used to interconnect a 1000 Base-T Ethernet network, VLAN or Fibre Channel network between the sites.

Figure 18 shows an Ethernet network or a VLAN connection between two sites. The four edge switches are connected together in a ring. The spanning tree protocol is used to determine active path between the sites.

Spanning TreeSite 2Site 1

Figure 18. Two fiber links routed physically apart are used to interconnect the sites.

DATA CENTER LAN

48

6.3.3 Data connectivity and routing

For customers to be able to benefit from the services from a failover site, data connectivity must be arranged to the failover site as well. The same dimensioning is valid as for the primary site, but there must be a way to automatically reroute the traffic.

With SAP Contact Center, the service is reached at the failover site (site 2) with the same IP address as it was at the primary site (site 1).

A virtual router cluster running HSRP (hot standby router protocol), in close association with a rapid-converging routing protocol such as OSPF (open shortest path first), is used to do the rerouting.

Two or more routers running HSRP in, for example, the service provider network appears as one virtual router. HSRP is used between the routers in the HSRP group to decide the active router.

Another similar pair is used in the customer LAN.

The routers of the HSRP group in the service provider network are connected over data links to routers in the HSRP group in the customer LAN.

Each group has only one active router at a time.

The active router becomes inactive, if the Ethernet port of that router goes down or if the serial port connected to the WAN goes down. In this case, another router in that HSRP group becomes active and continues routing the traffic.

HSRP

Group

Virtually one router

Service

Provider

Network

Common

Broadcast

Domain

Site 1 Site 2

HSRP

Group

Virtually one router

Customer

Network

Ethernet Ethernet

EthernetEthernet

Serial Serial

Serial Serial

WAN OSPF

Figure 17. HSRP and a rapid converging routing protocol is used to connect failover sites to the customer.

HSRP does not inform the other HSRP group of an event where the active router changes. If the Ethernet port of an active router goes down and the active router in that group is changed, traffic from the other group is still destined over the WAN to the previously active router. Therefore, a routing protocol is needed to cover the return path.

DATA CENTER LAN

49

6.3.4 Distributed real-time mirrored SAN

For data to be available at the failover site, a distributed real-time mirrored SAN (storage area network) system is recommended. SAN systems have the ability to hide physical disk structures from hosts and maintain mirrored and distributed copies over several disks even in separate locations.

Such disks appear to the hosts as single logical disks and are mounted, for example, by SQL clusters at failover.

6.3.5 Incoming call routing

In multi-site landscapes, gateways an SIP trunks are usually also distributed over the sites. The telephone network considers the E1/T1/J1 line alive practically as long as the gateway is powered on and the line is connected and intact regardless of the data connectivity between the service provider network and the customer network or between the service provider sites.

For occasions when gateways on either site are not able to respond reasonably to incoming calls, for example, no answer is sent from the gateway to the PSTN, an alternative destination is required the incoming calls. The primary alternative destination would be respective gateways on the other site, but overflows could be defined to any PSTN destination.

SIP OPTIONS PING can be used to determine if a particular SIP trunk is alive.

6.3.6 Arranging cluster and HAC nodes in each site

Running multi-site services requires configuring SAP Contact Center virtual unit instances to each site for failover purposes. The configuration of a SAP Contact Center virtual unit is aware of only the IP addresses, not the locations and thus, multi-site setups are equal to single-site setups in regard to the configuration of the SAP Contact Center software.

Running multi-site services requires also for databases and file sharing services to be available at both sites. This is achieved using Microsoft cluster services, SQL clusters and distributed real-time mirrored SANs.

CUSTOMER LAN

50

7 Customer LAN

The customer LAN refers to the LAN where the SAP Contact Center service is used. Different site topologies are already covered in the section 1.6, Introduction to customer LAN. 100 Base-T and/or 1000 Base T switched networks are recommended. There are two concerns related to the customer LAN:

- Availability

- Ability to carry quality voice

7.1 Availability

For the customer LAN availability, valid techniques are explained in:

- Minimizing network distances is a network hygiene matter and is explained in the section 6.1.1, Minimizing network distances

- Ring topologies can be used to interconnect departments, floors and sites as explained in the section 6.3.2, Connecting sites together

- For sites in different subnets, HSRP in combination with a rapid-converging routing protocol can be used as explained in the section 6.3.3, Data connectivity and routing

7.2 Ability to carry voice

The ability of a 100 Base-T or 1000 Base-T switched LAN to carry quality voice depends on the path the voice has to traverse on the LAN and the utilization and health of the LAN along that path. Utilization can be measured using network analyzers and reviewing switch statistics.

If there is heavy utilization and especially if there are heavy load peaks, it is advisable to find out the cause of the heavy utilization and/or the heavy peaks to verify that they are permissible and rational. When it is confirmed and possibly counter-measured that there is no dispensable traffic, a utilization baseline has been found. This baseline is used to recognize the available capacity for voice.

It should be observed that average utilization is not the whole truth about the ability to carry voice. A LAN with very modest average utilization but frequent high load peaks may show totally unworthy of carrying voice. The high load peaks may cause significant distortion to voice. A LAN carrying most of the calls perfectly well but at the same time disrupting the voice a few times a day is not acceptable.

Prioritizing traffic is an efficient method to attach heavy load peaks in a LAN where the average utilization is moderate.

7.2.1 Prioritizing traffic

Voice can be prioritized over other traffic in many ways. Common to all of these is that:

- There are some means to identify and categorize traffic

- Prioritization is done on queuing devices, such as switches

Voice traffic can be identified by the ToS bit set by SAP Contact Center or by constructing access lists on routers or switches filtering traffic into categories based on, for example, sender and/or receiver IP address or protocol. For configuration details see the documentation of the network device.

CUSTOMER LAN

51

Port n

input buffer

Port x

output bufferPort 2

input buffer

Port 1

input buffer

High Priority

Low Priority

Medium Priority

Eth

Eth

Categorization

High priority

queues are

emtied first

Figure 18. Frame queuing.

Figure 18 shows the principal of queuing and prioritizing traffic. A received Ethernet frame is buffered in the input buffer. The frame is analyzed to determine the category of it and moved to the buffer with respective priority. Frames in higher priority buffers are transmitted before frames (depending on the prioritization algorithm) in lower priority buffers. Frames in each buffer have no mutual priority, they are sent on a first-in first-out basis.

7.2.2 Verifying the LAN health

Switch statistics can be easily, and often very efficiently, used to verify the LAN health. Switch statistics usually show:

- Information about the utilization: The number of bits and packets received and sent per each port.

- Buffer overflows: May indicate too heavy utilization, bad network topology or malfunctioning hardware.

- Suspected speed and/or duplex mismatches: Indicates configuration problems. Auto settings might not work properly or manual settings do not match.

- The number of collisions and late collisions: May indicate too heavy utilization, malfunctioning hardware or bad network topology.

For details, see the documentation of the switch.

STORAGE SYSTEMS

52

8 Storage systems

Storage systems refer to the disks, disk arrays and SAN systems used for storing data. SAN systems use disk arrays internally. Disk arrays provide better availability and sometimes also faster performance than single disks. Faster performance is achieved especially in reading operations by reading several disks in parallel. SAN systems are mostly based on high speed optical fiber connections providing better throughput than traditional connections.

8.1 RAID arrays

RAID stands for redundant array of inexpensive disks and is a technology that employs simultaneous use of two or more hard disk drives that appear as one logical drive in the operating system. There are various RAID designs that all involve increased data availability or faster performance. Key RAID concepts are:

- Mirroring Mirroring involves copying data to more than one disk.

- Striping Striping involves splitting of data across more than one disk.

- Error correction. Error correction involves storing redundant data such as parity to enable problem detection and possibly problem fixing.

The most interesting RAID designs or levels are:

- RAID 1 All data is written to two identical disks, which allows for loss of one disk without data-loss.

- RAID 5 Striped set with distributed parity allowing for loss of one disk without data-loss.

- RAID 1+0 (or RAID 10). Two or more mirrored sets are striped to provide a bigger disk allowing for loss of several disks as long as no mirror set loses its both disks.

Disk 1 Disk 2

Logical disk

RAID 1

Figure 19. RAID 1

Logical

disks

A,B&C

RAID 5

Disk 1 Disk 2 Disk 3 Disk 4

A1

B1

C1

A2

B2

Cp

A3

Bp

C2

Ap

B3

C3

Figure 20. RAID 5 with 3 logical disks.

RAID 1 arrays are recommended to be used in SAP Contact Center application servers with local disks and for the operating system in SQL clusters. RAID 5 arrays or RAID 1+0 arrays are recommended to be used as database storage.

8.2 SAN systems

Storage area network (SAN) is an architecture for attaching remote computer storage devices such as disk

STORAGE SYSTEMS

53

arrays and tape libraries to servers in a way that they appear as local disks to the operating system. SAN usage usually simplifies storage administration and adds flexibility since storage devices do not have to be physically moved to move storage from one server to another. SAN also allows for booting from the storage devices.

It is recommended that SAP Contact Center application servers boot from SAN but that cluster servers, such as Microsoft SQL clusters, have local disks for the operating system and that the databases are on the SAN.

SANs usually utilize a Fibre Channel fabric topology made up of Fibre Channel switches, where devices are connected to each other through one or more Fibre Channel switches. Host bus adapters (HBA) are used connect servers to Fiber Channel switches. Each server and storage is connected to two switches for fault tolerance.

Storage 1 Storage 2

Fiber Channel

Switches

SAN

attached

servers

Figure 21. Fibre Channel switched fabric topology

Figure 21 shows storages 1 and 2 that reside at different sites. The figure contains cascaded switches for illustration purposes. The shown topology could be run with two Fibre Channel switches.

Using manufacturer-specific SAN options, logical disks can be mirrored to different storages making data available in real-time at different locations.

Snapshots can be used to preserve a copy of the data at the given moment. Benefits of snapshots are, for example, separated partitions that can be analyzed without influencing the production environment and establishing truly identical test environments.

9 Telephony and data connections

Data and telephony connections are used to connect the service center to the outside world. Data connections are connected to the customers and telephony connections are connected to the PSTN. Both are covered earlier in this document:

TELEPHONY AND DATA CONNECTIONS

54

- Telephony connections are covered as follows: 1.4 Introduction to gateways and SIP trunks 1.8 Introduction to telephony and data connections 5 Gateways and SIP trunks

- Overall topology and service and access links are covered as follows: 1.1 Introduction to site landscapes and connectivity 1.6 Introduction to customer LAN 6.6.3 Data connectivity and routing

9.1 Telephony connections

Public network and PBX interfaces, ITU-T G.703 RJ48 (120 ohm), are provided by the gateways. These interfaces are connected to E1/T1/J1 lines or spans provided by an operator. These lines are Time Division Multiplexed (TDM), for example an E1 line is divided into 32 channels of which channels 1 – 15 and 17 – 31 are used for voice and 0 and 16 are used for synchronization and signaling. The signaling used is S ISDN.

Every 3.91 microseconds 8 bits from one channel is sent down the line followed by 8 bits from the next channel during the next 3.91 microseconds, and so on, in a round-robin fashion throughout all the channels and thus, 32 channels are used once every 125 microseconds.

Service providers may consider preparing for coming demands by obtaining, for example, E3 or bigger trunks to their sites in advance and having the telco splitting them into E1 lines at the site. One E3 trunk contains 16 E1 lines. The suggested arrangement helps maintaining the technical sanity and might speed up new deployments as only configuration remains to be done when taking more lines in use.

Lines are taken in use by subscribing them. It is recommended that subscriptions are made by the customers and that they are invoiced for the telephone traffic by the telco directly.

Subscriptions include a telephone number range. In most cases only numbers from this number range can be shown as A numbers or calling party numbers.

0 1 2 3 16 17 3115 0 1 2 3 16 17 3115

1 1 1

2 2 2

3 3 3

15 15 15

17 17 17

31 31 31

1 1 1

2 2 2

3 3 3

15 15 15

17 17 17

31 31 31

Figure 22. E1 Time Division Multiplexing. Each timeslot is 3,91 microseconds.

Telco provided SIP trunks carry both the control protocol (SIP) and the audio (RTP). SIP trunks are nowadays preferred over ISDN trunks in many cases.

9.2 Data connections

Data connections refer to service and access links. Service links are high bandwidth connections from a telco’s network to the site(s) of a service provider. Service links provide similar preparedness on the data network side as using E3 trunks does on the telephone network side. Similarly, service links provide better technical sanity, cost efficiency and expedited deployment times because the access links only need to be physically installed.

Dimensioning of service links is straight-forward as the required bandwidth is the sum of the bandwidth of the access links. Dimensioning of access links relies on:


55

- Maximum number of simultaneous calls

- The codec G.711 or G.729

- The packet periods, 10, 20, 30, 40 ms, and so on.

- Estimated usage profile

The maximum number of simultaneous calls equals the number of (assuming all gateways are at the service provider):

- E1 lines x 30 or

- T1 or J1 lines x 23

The codec G.711 creates a 64 kbit/s stream for a signal sampled at 8 kHz and G.729 creates an 8 kbit/s stream correspondingly. This stream is the payload to be carried over the IP network. The stream is sliced into packets of, for example, 20 ms of the stream. To be able deliver these packets, they are wrapped into RTP, UDP and IP headers and finally, also in transport medium dependent headers. The choice of packet length is a trade-off between latency and packet overhead.

20 ms of a G.711 stream is 64000 kbit/s x 0.02 s = 1280 bits -> 1280 bits / 8 = 160 octets. 20 ms of a G.729 stream is 8000 kbit/s x 0.02 s = 160 bits -> 160 bits / 8 = 20 octets. It should be noticed that some gateways and/or IP desk phones accept only multiplies of 20 ms and therefore, 20 ms is a good default value.

As figure 23 shows, carrying RTP voice over Ethernet involves 78 octets overhead, Ethernet 38 octets and IP/UDP/RTP 40 octets. The 38 octets are transmission-media dependent and apply to Ethernet only. HDLC (High-Level Data link Control) and PPP (point-to-point protocol) are typically used, for example, on 2 Mbit/s access links based on the SDH network. HDLCs overhead is 6 to 7 octets and PPPs overhead is 7 to 9 octets.

Ethernet Preample (8)

Ethernet Header (14)

IP, UDP & RTP Header (40)

20 ms G.711 Payload (160)

Ethernet CRC (4)

Ethernet Inter-Frame Gap (12)

Figure 23. Ethernet frame carrying G.711 over IP

The IP/UDP/RTP header can generally be thought of as a fixed overhead of 40 octets per packet, though on point-to-point links RTP header compression can reduce this to 2 to 4 octets (RFC 2508).

Sending 20 ms voice in each Ethernet frame means that 50 frames are send each second. This gives total bandwidth demand of:

- 50 times per second x (78 octets + 160 octets) x 8 = 95.2 kbit/s for G.711 over Ethernet

- 50 times per second x (78 octets + 20 octets) x 8 = 39.2 kbit/s for G.729 over Ethernet

- 50 times per second x (7 octets + 160 octets) x 8 = 66.8 kbit/s for G.711 over HDLC

- 50 times per second x (7 octets + 20 octets) x 8 = 10.8 kbit/s for G.729 over HDLC

- 50 times per second x (9 octets + 160 octets) x 8 = 67.6 kbit/s for G.711 over PPP


56

- 50 times per second x (9 octets + 20 octets) x 8 = 11.6 kbit/s for G.729 over PPP

Certain codecs support silence suppression. Voice Activity Detection (VAD) suppresses the transmission of data during silence periods. As only one person normally speaks at a time, this can reduce the demand for bandwidth by as much as 50 percent. The receiving codec will normally generate comfort noise during the silence periods.

The bandwidth requirement is full duplex.

As a conclusion, based on earlier experiences a good rule of thumb is that G.711 requires 80 kbit/s and G.729 requires 40 kbit/s per simultaneous call on a HDL or PPP link. This includes the voice stream, signaling information and CDT user interface. This rule may not be applicable in inbound and outbound call center cases, where calls are interleaved very little or not at all.

Capacity demands for other channels, such as e-mail, are estimated based on information received from the customer, for example, average sizes and e-mail frequencies. This capacity is added on top of the capacity calculated for telephony.

USER TERMINALS

57

10 User terminals

The SAP Contact Center user terminals are CDT, Convergence (SAP Contact Center soft phones) and IP desk phones. CDT provides the broadest scale of functionality and is the primary user interface. IP desk phones are usually used in negotiation rooms and other places where PCs are not available.

10.1 CDT and Convergence

CDT is a browser based phone including sophisticated functionality for call center agents. CDT requires Microsoft Internet Explorer (IE). For required IE settings, refer to the user documentation of SAP Contact Center. Convergence is a soft phone with more basic functionality. It is an alternative for users that don’t need the full feature set of CDT.

USB handsets and headsets are used with CDT and Convergence. Headsets are also available as wireless. Handsets may include keypads for dialing, volume control, mute, on-hook and off-hook functions. Headsets are either monaural or binaural, that is, they come with one earpiece or with two earpieces.

USB devices are powered either via the USB bus or they have external power supplies. In cases where many USB devices are used and/or high power USB devices are used, consider using external USB HUBs with external power supplies. The current supplied by the USB bus is limited to maximum of 500 mA.


10.2 IP Desk Phones

IP desk phones in SAP Contact Center are stand-alone phone devices connected to a SAP Contact Center system over the Ethernet LAN. These phones run SIP and are configured to register to the SAP Contact Center SIP Bridge.

The IP desk phone settings may be done manually using the keypad. The phones usually contain a web server for administration and additional configurations can be done using a browser once mandatory IP settings are effective, which are:

- IP address

- Subnet mask

- Default router (in some cases)

Other important settings for IP desk phones are:

- SIP registrar and proxy IP addresses

- Subscription number

- NTP (network time server) IP address

IP desk phones include usually configurable speed dial functions and downloadable telephone number directories.

IP desk phones can also be configured automatically using DHCP (Dynamic Host Configuration Protocol) and TFP (Trivial File Transfer Protocol).

USER TERMINALS

58

DHCP servers are assigned a pool of IP addresses from which they lease IP-addresses to hosts in reply to their DHCP requests. The DHCP reply typically contains at least the following information:

- IP address

- Subnet mask

- Default router

- DNS (Domain Name System) IP address

The DHCP may be configured to provide, for example, the following additional information as well:

- NTP server IP address

- TFTP server IP address

Some IP desk phones are capable of retrieving and storing detailed configuration information from and to TFTP servers. If configured to do so, an IP desk phone does the following when it boots:

- Sends DHCP request (layer 2 broadcast)

- Receives a DHCP reply

- Activates the received mandatory IP settings

- Requests for its configuration file (recognized by the MAC address) from the TFTP server

- Configures itself according to the received settings

The behavior is manufacturer dependent in case the DHCP and/or TFTP requests fail. In some cases it is to use to the previously active settings.

TFTP servers are also useful for making configuration backups even if the initial configuration is done in some other way.

IP desk phones can be, in most cases, powered by external power supplies or by PoE (Power over Ethernet). PoE requires the connected switch to support it or to arrange a separate PoE adapter between the switch and the IP desk phone. PoE utilizes otherwise unused wires in CAT 5/6 LAN cables.

PoE

AdapterUnpowered

LAN cable

Powered

LAN cable

To power

supply

Figure 24. Powering IP desk phones over Ethernet.


SECURITY

59

11 Security

SAP Contact Center security relies on infrastructure security described earlier as follows:

- 1.5 Introduction to data center LAN introduces a layered network structure

- 1.10 Introduction to security introduces some security viewpoints

- 3.1 Physical security covers aspects of physical security

- 4.3.3 Certificates covers certificates

- 6.2.1 Access control covers the benefits of access control

11.1 Network traffic control

Network traffic control plays a crucial role in SAP Contact Center security. The layered network structure of a data center forms three security zones. The layered structure is designed to allow only necessary traffic at each level and to facilitate connections from higher security levels to lower security levels only between known endpoints.

In the access network layer, where the customer is considered as a known endpoint, more granular segmentation is advised by constructing VLANs for different customers. Routing between customers is not recommended. If there is a demand to pass VoIP calls from a customer to another, it should be done via MRS.

Network traffic control is implemented with firewalls and access-lists on switches and routers and using VLANs. For information needed to configure access lists, see the documentation of the SAP Contact Center ports and protocols.

11.2 Identification, authentication and authorization

SAP Contact Center administrators and users are identified and authenticated with user IDs and passwords.

Connection servers are identified and authenticated with server certificates.

Partially authorized SAP Contact Center administrators are authorized by fully authorized SAP Contact Center administrators.

SAP Contact Center users are authorized by SAP Contact Center administrators

11.3 Signed software modules

The essential SAP Contact Center software modules are signed with publisher ID certificates to indicate the origin and the integrity of the modules.

11.4 Encrypted network traffic

The most vulnerable network connections can be encrypted.

AVAILABILITY AND MANAGEABILITY

60

12 Availability and manageability

The primary availability concept is implementing overall fault tolerance. Fault tolerance is achieved as follows:

- Spanning tree, introduced in 6.3.2 Connecting sites together. This is applicable for in LANs in general

- NIC teaming, introduced in 6.2.3.2 Teaming

- HSRP, introduced in 6.3.3 Data connectivity and routing

- Multiple sites, introduced in 6.3 Multiple sites

- Facility recommendations, introduced in 3 Environmental and facility recommendations

- SQL and File server clusters, introduced in 4.3.1 Microsoft SQL Server

- Server and hardware fault tolerance, introduced in 4.1.2.2 Server chassis and operability

- SAP Contact Center HAC (high availability controller), explained below

12.1 SAP Contact Center HAC

HAC is the SAP Contact Center high availability controller installed on every SAP Contact Center server, also referred to as a HAC node. HAC monitors the health of local services, typically each virtual unit, and communicates it with other HAC nodes with a kind of a heart-beat protocol over the network.

For example, SAP Contact Center components for a particular service are installed on two or more HAC nodes and configured with identical settings. One of these is active at any given time and referred to as the active node or the active instance. The standby (spare) nodes remain inactive as long as they receive OK status information from the active node. Failover nodes are prioritized primarily by the name of the instance element and secondarily by the ID of the instance element. The failover entity is one or more virtual units.

VU_CORE

VU_HAC

HAC Node 2

VU_CORE

VU_HAC

HAC Node 3

VU_CORE

VU_HAC

HAC Node 1

Regular status

notifications

Regula

r sta

tus

notifications

Figure 25. HAC nodes. The node 1 is active and the nodes 2 and 3 are prepared failover destinations.

HAC failover can also be initiated manually, for example, for the duration of maintenance tasks. HAC can also be configured to notify the SAP Contact Center Alarm Server about its statuses.


61

12.2 SAP Contact Center Alarm Server

The Alarm Server retrieves status information from HAC nodes. The Alarm Server can be configured to forward these alarms to configured destinations as:

- E-mail messages

- SMS messages

- SNMP (simple network management protocol) traps

12.3 SNMP

SNMP (simple network management protocol) is part of the Internet Protocol Suite as defined by Internet Engineering Task Force (IETF). SNMP is used in network management systems to monitor network attached devices for conditions that warrant administrative attention.

Several SNMP management systems exist on the market and there is no particular preference of any of them.

Basically SNMP defines the following message types:

- SNMP GET REQUEST

- SNMP SET REQUEST

- SNMP TRAP

SAP Contact Center sends only SNMP traps. SNMP GET and SET messages can be used for managing other SAP Contact Center infrastructure devices supporting SNMP.

SNMP management systems typically include sophisticated functions, such as ability to:

- Filter the most relevant messages

- Send e-mail and SMS alerts initiated by events in the monitored system.

- Log events for further investigation.

- Export event data to files, sheets or syslog servers for reporting purposes.


62

Figure 26. SNMP network view.

Figure 27. SNMP SAP Contact Center servers view.

12.4 Miscellaneous

SAP Contact Center operators should consider stopping unnecessary Windows services to minimize server and network utilization and vulnerability. Furthermore SAP Contact Center operators should consider stopping the optimization of SQL Server performance. For more information see the documentation of Windows Server and SQL Server.

SAP Contact Center Infrastructure Administrator (IA) an System Configurator (SC) are used to install and configure SAP Contact Center components. For more information see the documentation of SAP Contact Center.

DEPLOYMENT, SOFTWARE DISTRIBUTION AND CONFIGURATION

63

13 Deployment, software distribution and configuration

Deployment issues were introduced in 1.12 Deployment, software distribution and configuration and they have also been discussed through this document. Deployment may be seen of as a twofold project. On the one hand, it deals with SAP Contact Center functionality and parameter definitions, such as queues, prompts and telephone numbering, but on the other hand, deals with technical infrastructure definitions and preparations.

Service providers may consider running different SAP Contact Center infrastructures with different service level characteristics, such as 24/7 and 24/5. The implementation of each service agreement would be possible in a SAP Contact Center infrastructure where the service level characteristics match or exceed the requirements in the corresponding service level agreement.

This arrangement may clarify the urgency of administrative and operative alternation in case of incidents. This arrangement also adds flexibility for maintenance windows during which routine maintenance tasks are performed without explicit notifications.

13.1 Software distribution

Software components required by CDT are available as Windows Installer files and distributed and installed to the client workstations either manually or by means of Microsoft SMS or Microsoft AD group policies. The first-time installation requires authorization for installing software and is typically done with administrative user rights. Subsequent updates can be performed automatically by SAP Contact Center and do not require administrative intervention.

Figure 28. Windows Installer view of SAP Contact Center Terminal Setup.

The terminal.msi file contains all client-side software components but they are also available as separate installation files. For example, added and/or updated support for headsets and handsets are provided as terminal_HS_device.msi files, where device is the name of the device or its manufacturer.

SIZING

64

14 Sizing

Sizing is covered in this document as follows:

- 1.13 Introduction to sizing

- 2.3 Virtual units

- 4.1.1 The number of servers

- 4.1.2.3 Server specifications

- 4.2 Operating systems

- 4.3.1 Microsoft SQL Server

- 5 Gateways and SIP trunks (the sizing information is available in appendix A)

- 6 Data center LAN

- 6.1.2 LAN capacity

- 6.3 Multiple sites

- 7 Customer LAN

- 9 Telephony and data connections

- Appendix A Sample SAP Contact Center servers

The basic principle is that SAP Contact Center is a modular system that scales up by adding components. that is, components with high utilization can be multiplied to increase total capacity and to share the load between several units.

Database server performance is increased by scaling up the hardware, such as disks, memory and CPU.

One CEM server is capable of handling at least 100000 calls per hour.

For other components, the following maximum limits are recommended:

- HBR 1000 simultaneous calls

- SBR 2000 simultaneous calls

- MRS 800 simultaneous prompts or recordings or 1000 simultaneous NAT calls or SRTP calls

- CS 500 simultaneous connections

INTEROPERABILITY WITH OTHER SYSTEMS

65

15 Interoperability with other systems

Interoperability with other systems, such as, Cisco Call Manager (CM) or Microsoft Lync is achieved at basic call level by sharing gateway(s) between the systems and configuring respective call routing on the gateway(s) similar to the configuration in chapter “Connecting to a PBX”.

PSTN

LAN

SAP CCtr MicrosoftLync

Extensions

100 - 199

Extensions

200 - 299

xxx200 -

xxx299

xxx100 –

xxx199

xxx100 –

xxx199

xxx200 -

xxx299

Outgoing

calls

Figure 29. SAP Contact Center and Microsoft Lync are using a common gateway.

Incoming calls are routed based on the dialed number to either SAP Contact Center or Microsoft Lync. A dial peer is configured on the gateway (Cisco in this sample) for both SAP Contact Center and Microsoft Lync. Both dial peers define a session target (the SAP Contact Center and Microsoft Lync SIP counterparts) with which the control protocol is negotiated and a destination pattern that matches the dialed telephone numbers with either of the systems. Outbound calls are routed on both systems to the gateway and by the gateway to the PSTN.

LAN


Extensions

100 - 199

Extensions

200 - 299

200 - 299

100 - 199 100 - 199

Figure 30. Calls between SAP Contact Center and Microsoft Lync routed via common gateway capacity.

Calls between SAP Contact Center and Microsoft Lync can be routed via the gateway. The drawback of this configuration is that internal calls consume gateway capacity.

INTEROPERABILITY WITH OTHER SYSTEMS

66

An alternative way to route calls between SAP Contact Center and Microsoft Lync is to configure a SIP trunk between them. The same is true for Cisco Call Manager.

PSTN

LAN


Extensions

100 - 199

Extensions

200 - 299

xxx200 -

xxx299

xxx100 –

xxx199

xxx100 –

xxx199

xxx200 -

xxx299

200 - 299

100 - 199

Outgoing

calls

Figure 31. Optimizing call paths.

GLOSSARY

67

16 Glossary

ABBREVIATION (TERM) DESCRIPTION OR SYNONYM

10Base-T

100Base-TX

1000Base-T

Standards for Ethernet over twisted pair or copper-

based computer networking physical connectivity

methods. The currently most widely used of these are

10BASE-T, 100BASE-TX, and 1000BASE-T running

at 10 Mbit/s, 100 Mbit/s and 1000 Mbit/s (1 Gbit/s)

respectively.

3G (third generation) The level of development related to wireless

technologies. The preceding levels were 1G (included

analog standards such as FDMA and NMT), 2G

(included digital standards such as CDMA and GSM),

and 2.5G (included the packet-based GPRS

standard). The 3G standards include UMTS (based on

GSM) and WCDMA (based on CDMA).

A number The number where the call or message comes from

(i.e. the caller’s number or the source number).

Absence A user is away or not available and cannot be

reached.

ACD (automatic call distributor) A module which manages inbound calls by using the

destination number.

A/D, A/D conversion Analog to digital conversion and vice versa

ActiveX ActiveX is a component object model (COM)

developed by Microsoft for Windows platforms.

Software based on ActiveX technology is prevalent in

the form of Internet Explorer plugins and, more

commonly, in ActiveX controls, ActiveX based

applications launched from web pages

Agent A user who handles queue calls and interacts with

customers. Usually related to contact centers.

AS (alarm server) A server receiving alarms from a HAC node and

distributing those alarms according to its rule sets.

ASP (application service provider) An enterprise that provides other enterprises or

individuals remote access to application programs and

services over the Internet.

ATL, ATLTERMINAL The core module required for the phone functions in

the Communication Desktop (CDT) application. This

ActiveX component is installed on a client workstation.

Attended transfer An active call is not transferred to another number

until you see whether it is answered or not. The call is

put on hold automatically, and you can release and

continue it if the other party does not answer.

Compare to the blind transfer method.

Auto-allocation mode The call queue mode where you get automatically the

next inbound call from the queues you are currently

logged into (i.e. serving as an agent). Each call is

offered separately to the agents who are logged into

the queue. Compare to hunt group mode.

Availability information Indicates whether a user is absent or present. Related

to PRS profiles in the Communication Desktop (CDT)

application.

http://en.wikipedia.org/wiki/Copper

http://en.wikipedia.org/wiki/Megabit_per_second

http://en.wikipedia.org/wiki/Gbit/s

http://en.wikipedia.org/wiki/Component_object_model

http://en.wikipedia.org/wiki/Microsoft

http://en.wikipedia.org/wiki/Windows

http://en.wikipedia.org/wiki/Software

http://en.wikipedia.org/wiki/Internet_Explorer

http://en.wikipedia.org/wiki/Browser_plugin

GLOSSARY

68


B number The target of the call or message (i.e. the destination

number).

Blind transfer An active call is transferred to another number without

knowing whether the call is answered or not. Compare

to the attended transfer method.

Bridge (H.323 or SIP) A core module for connecting the registered terminal

devices and the gateways to the CD core module.

C number The target of the call which is forwarded from the B

number.

Campaign Defines the contents of the outbound call set (such as

the customers, scripts and special rules) in the

Outbound (OB) application.

CD (Call Dispatcher) The core module for low-level call handling.

CDT (Communication Desktop) An end user application related to enterprise

telephony systems and contact center operations.

CEM (Communication Event Manager) The core module for top-level call handling.

CEM database The system database for call handling.

CD (call dispatcher) The core module for low-level call handling.

Chat, chatting Real-time communication between users by using

computing devices.

ClientCom The communication interface between the client-level

applications.

Codec (coder/decoder) A module which combines analog-to-digital and digital-

to-analog conversion.

Company An external customer or an internal employer in the

CPM database. Contacts are always linked to one or

more companies.

Contact An external customer or an internal employee in the

CPM database. When internal user accounts are

transferred from the CEM database to the CPM

database, they are interpreted as contacts. Contacts

are always linked to one or more companies.

Contractor The party that uses the services of an outbound call

center to run its outbound campaigns. Used in the

Outbound (OB) application.

CPM Administrator An administration application related to the CPM

database and predefined outbound call campaigns.

CPM database (Contact Process Manager)The system database for

managing customer information and activities (such as

tasks).

CS (connection server) A SAP Contact Center module connecting terminals to

other SAP Contact Center components.

CTI (computer-telephony integration) The use of computers for managing and making

telephone calls.

Customer An external company or contact in the CPM database.

Customizer, customizing file A text file in the CEM server which contains dedicated

customer-specific values.

DB, db (database) A collection of information which is organized by using

predefined rules.

DHCP (dynamic host configuration protocol) Dynamic Host Configuration Protocol (DHCP) is a

protocol used by networked devices (clients) to obtain

GLOSSARY

69


various parameters necessary for the clients to

operate in an Internet Protocol (IP) network.

Dialer A module (such as the third-party Sytel Softdial dialer)

which controls the outbound call sequence, timing and

agent assignment in the Outbound (OB) application.

Directory Either a CEM directory defined in the System

Administrator application, or a segment which is

displayed as a directory in the Communication

Desktop (CDT) application.

DMZ (demilitarized area) In computer security, a demilitarized zone, a demarcation zone or perimeter network, is a physical or logical subnetwork that contains and exposes an organization's external services to a larger, untrusted network, usually the Internet. The purpose of a DMZ is to add an additional layer of security to an organization's Local Area Network (LAN); an external attacker only has access to equipment in the DMZ, rather than the whole of the network.

DTMF (dual tone multi-frequency) The signals you generate by pressing the keypad of a

traditional phone.

DU (Data Universe) The data warehouse and reporting software.

E1, E1 line A single physical wire in telecommunications that can

be used to carry many simultaneous voice

conversations. It is widely used in almost all countries

outside USA, Canada and Japan. The line data rate

for E1 is 2.048 Mbit/s (full duplex) which is split into 32

time slots and can carry 30 simultaneous voice

conversions.

EDGE (Enhanced Data rates for Global Evolution) Also known as EGPRS. A packet switched radio

network for data transmission by mobile devices. A

successor of GPRS. Also considered a 2 or 2.5 G

(second generation) network.

E-mail channel The queue type which is used for receiving and

handling e-mail messages in the Task Manager (TM)

application.

ETC (external terminal controller) ETC converts IP desk phone functionality by imitating

BCM soft phones and thus standardizes IP desk

phone features towards CEM.

External agent A user who is logged into the software from an

external number (mobile or fixed). External agents

serve in queues remotely.

G.711 G.711 is an ITU-T standard for audio companding. It is

primarily used in telephony.

G.729 G.729 is an audio data compression algorithm for voice that compresses voice audio in chunks of 10 milliseconds. G.729 is mostly used in Voice over IP (VoIP) applications for its low bandwidth requirement. Standard G.729 operates at 8 kbit/s.

GK (gatekeeper) (H.323 or SIP) A core module for registering the terminal devices to

the CD core module. A SIP gatekeeper is also called

registrar.

GMT/UTC (Greenwich Mean Time/Coordinated

Universal Time)

The standard time system used in the software. Times

in different time zones are calculated in relation to the

http://en.wikipedia.org/wiki/Internet_Protocol

http://en.wikipedia.org/wiki/Computer_security

http://en.wikipedia.org/wiki/Subnetwork

http://en.wikipedia.org/wiki/Local_Area_Network

http://en.wikipedia.org/wiki/ITU-T

http://en.wikipedia.org/wiki/Companding

http://en.wikipedia.org/wiki/Telephony

http://en.wikipedia.org/wiki/Audio_data_compression

http://en.wikipedia.org/wiki/Voice_over_IP

http://en.wikipedia.org/wiki/Bit_rate

GLOSSARY

70


GMT time.

GPRS (General Packet Radio Service) A packet switched radio network used for data

transmission by mobile devices. GPRS is a 2G

(second generation) network.

GUI (graphical user interface) The graphical interface for human-computer

interaction (HCI). GUIs make it easier to use the

software applications, especially when compared to

command-based interfaces.

GW (gateway) (H.323 or SIP) An external module for connecting the system to an

external network (usually to the PSTN network).

H.323, H323 A standard protocol for audio, video, data, internet

phone, and VoIP transmissions.

HA (high availability) A system or module which is operational for a required

time without uncontrolled interruptions.

HAC (High-Availability Controller) An administration application related to the system

infrastructure.

HBA (host bus adapter) Used in San systems to connect servers to storages.

HBR (H.323 bridge) The H.323 trunk interface in SAP Contact Center.

Hunt group mode The call queue mode where you can select any

inbound call from the queues you are currently logged

into (i.e. serving as an agent). Each call is offered

simultaneously to all agents who are logged into the

queue. Compare to auto-allocation mode.

IA (Infrastructure Administrator) An administration application related to the system

infrastructure.

ICL (infrastructure compatibility list) List of SAP Contact Center compatible devices

IE ( internet explorer) Windows Internet Explorer (formerly Microsoft Internet

Explorer abbreviated MSIE), commonly abbreviated to

IE, is a series of graphical web browsers developed by

Microsoft and included as part of the Microsoft

Windows line of operating systems starting in 1995.

IIS (Internet Information Server) A Microsoft server product which is used for various

web-related tasks, such as managing services and

sharing information.

iLO (integrated lights-out) Integrated Lights-Out (iLO) Standard combines basic

management functions and diagnostics with essential

Lights-Out functionality as standard components of the

server. Used by HP.

IM (instant message) Short messages sent and delivered by using the

Communication Desktop (CDT) application.

Inbound Incoming (communication events).

IP (Internet Protocol) The method and technology for sending data between

computers on the Internet.

IP phone A telephone based on IP technology.

IP v4 Internet Protocol version 4 (IPv4) is the fourth iteration of the Internet Protocol (IP) and it is the first version of

the protocol to be widely deployed.

ISDN Q.921 ITU-T Recommendation Q.921, is the second layer protocol on the ISDN protocol stack in the D channel.

ISDN Q.931 ITU-T Recommendation Q.931 is ISDN's connection control protocol. Q.931 is a layer 3 protocol, mainly used for the ISDN call establishment, maintenance,

http://en.wikipedia.org/wiki/Graphical_user_interface

http://en.wikipedia.org/wiki/Web_browser

http://en.wikipedia.org/wiki/Microsoft

http://en.wikipedia.org/wiki/Microsoft_Windows


http://en.wikipedia.org/wiki/Operating_system

http://en.wikipedia.org/wiki/Internet_Protocol

http://en.wikipedia.org/wiki/ITU_Telecommunication_Standardization_Sector

http://en.wikipedia.org/w/index.php?title=Q.921&action=edit&redlink=1

http://en.wikipedia.org/w/index.php?title=Q.921&action=edit&redlink=1

http://en.wikipedia.org/wiki/ISDN

http://en.wikipedia.org/wiki/D_channel

http://en.wikipedia.org/wiki/ITU_Telecommunication_Standardization_Sector

http://en.wikipedia.org/wiki/Integrated_Services_Digital_Network

http://en.wikipedia.org/wiki/Communications_protocol

GLOSSARY

71


and release of network connections.

ISP An Internet service provider is a company or business

that provides access to the Internet and related

services.

IVR (Interactive Voice Response) A system which supports interaction between the

caller and the system. For example, the caller may

hear a prerecorded prompt which instructs to enter

data with the phone keypad.

J1, J1 line A single physical wire in telecommunications that can


conversations. It is used in Japan. A J1 line can carry

23 simultaneous voice conversions.

LAN (local area network) A group of computing devices which are used over a

shared data line within a limited geographical area.

MAGENT The core module required for the messaging functions

in the Communication Desktop (CDT) application. This


MCB (Mobile Connection Bridge) The core module for connecting the SPS terminal

devices and the server modules securely.

MCTABUFF The core module required for ClientCom integrations

and the task management integration. This ActiveX

component is installed on a client workstation.

MMS (multimedia messaging service) A method for delivering multimedia data to mobile

phones and other devices.

Mobile phone A cellular telephone, cell phone, or portable hand

phone.

MPLS (multi protocol label switching) In computer networking and telecommunications, Multi

Protocol Label Switching (MPLS) is a data-carrying

mechanism that belongs to the family of packet-

switched networks. MRS (Media Routing Server) The core module for playing prompt files. It also

converts the RTP stream into a WAV file when a caller

leaves a voicemail message.

MsgCleaner The module cleaning old messages.

MsgToMail The module converting messages to e-mails.

MsgToSMS The module converting messages to SMS messages.

MSI The file format for Microsoft Windows Installer

packages. Usually data in installation packages is

compressed to decrease the size. The packages

make it easier to install software applications and

modules and to configure some initial settings during

the installation.

MTD (Multi-terminal Desktop) Functions for defining multiple terminal devices for

receiving inbound calls, and for selecting which one of

the devices is used when making outbound calls.

Used in the Communication Desktop (CDT)

application.

NAT (Network Address Translation) An IP address used in one network (the inside

network) is translated to a different IP address known

in another network (the outside network). Often

involves address mapping and firewall configuration to

http://en.wikipedia.org/wiki/Internet

http://en.wikipedia.org/wiki/Computer_networking

http://en.wikipedia.org/wiki/Telecommunications

http://en.wikipedia.org/wiki/Packet_switching

http://en.wikipedia.org/wiki/Packet_switching

GLOSSARY

72


improve security.

OB (Outbound) An end user application related to predefined

outbound call campaigns.

Operator A user who acts as a switchboard operator.

Outbound Outgoing (communication events).

PBX (private branch exchange) A traditional corporate telephone system which usually

includes switchboard hardware.

PCM, 64 kbit/s PCM (pulse-code modulation) Pulse-code modulation (PCM) is a digital

representation of an analog signal where the

magnitude of the signal is sampled regularly at

uniform intervals, then quantized to a series of

symbols in a digital (usually binary) code. PCM has

been used in digital telephone systems and is also the

standard form for digital audio in computers.

PDA (personal digital assistant) A hand-held device for mobile computing.

PDC (Predictive Dialing Controller) A CEM module which runs the outbound campaigns in

the technical sense. Used in the Outbound (OB)

application.

Person An external individual in the CPM database. Persons

are not connected to companies and are usually

private persons.

Phone for MS Office Outlook An extension application which makes it possible to

use some phone and availability functions in the MS

Office Outlook application.

PLMN (public land mobile net) In telecommunication, a public land mobile network (PLMN) is a network providing land mobile telecommunications services to the public. Access to PLMN services is achieved by means of an air interface involving radio communications between mobile phones or other wireless enabled user equipment and land based radio transmitters or radio base stations

POP (point-of-presence) An internet access point which has a unique IP

address and provides an access to the rest of the

Internet.

Presence A user is free and can be reached.

Prompt An audio message file in the WAV format.

PRI (Primary rate interface) The primary rate interface (PRI) is a

telecommunications standard for carrying multiple

DS0 voice and data transmissions between two

physical locations.

PRS (Personal Reachability Services) Functions related to profiles and availability

information. Used in the Communication Desktop

(CDT) application and Smartphone Suite (SPS)

application.

PRS profile An absence, presence or conference profile which

defines how inbound calls are handled depending on

your availability.

PSTN (public switched telephone network) The collection of interconnected public telephone

networks and systems.

QoS (quality of service) In the field of computer networking and other packet-

switched telecommunication networks, the traffic

engineering term quality of service (QoS) refers to

http://en.wikipedia.org/wiki/Modulation

http://en.wikipedia.org/wiki/Digital

http://en.wikipedia.org/wiki/Signalling_%28telecommunication%29

http://en.wikipedia.org/wiki/Sampling_%28signal_processing%29

http://en.wikipedia.org/wiki/Quantization_%28signal_processing%29

http://en.wikipedia.org/wiki/Binary_number

http://en.wikipedia.org/wiki/Telephone

http://en.wikipedia.org/wiki/Digital_audio

http://en.wikipedia.org/wiki/Computer

http://en.wikipedia.org/wiki/Telecommunication

http://en.wikipedia.org/wiki/Telecommunications_network

http://en.wikipedia.org/wiki/Mobile_phone

http://en.wikipedia.org/wiki/Air_interface

http://en.wikipedia.org/wiki/Radio

http://en.wikipedia.org/wiki/Mobile_phone

http://en.wikipedia.org/wiki/Wireless

http://en.wikipedia.org/wiki/Transmitter

http://en.wikipedia.org/wiki/Base_station

http://en.wikipedia.org/wiki/Telecommunication

http://en.wikipedia.org/wiki/DS0

http://en.wikipedia.org/wiki/Computer_networking

http://en.wikipedia.org/wiki/Packet-switched

http://en.wikipedia.org/wiki/Packet-switched

http://en.wikipedia.org/wiki/Traffic_engineering_%28telecommunications%29

http://en.wikipedia.org/wiki/Traffic_engineering_%28telecommunications%29

GLOSSARY

73


resource reservation control mechanisms.

Queue routing The rules for offering calls to the agents who are

serving in the queues in the auto-allocation mode.

R number The term used for the original external source number

(the A number) in the following special case: the

system is configured to display the original number

even when the call has been forwarded within the

system before it is finally forwarded to another

external number. Normally the system displays the

personal extension number or the queue number as

the source number.

RTP (Real-time Transport Protocol) A standard protocol for audio, video, data, internet


SAM (Service Availability Monitor) A core module which monitors the state and

responsiveness of systems by simulating phone calls

and HTTP requests.

SAN (storage area network) A Storage Area Network is an architecture to attach

remote computer storage devices such as disc arrays

to servers in such a way that, to the operating system,

the devices appear as locally attached.

SBR (SIP Bridge) A SAP Contact Center component acting as SIP

registrar towards SIP devices and performing protocol

translation from SIP to proprietary protocols towards

other SAP Contact Center components and vice

versa.

SBR (skill-based routing) A queue routing method in the software. The software

offers calls to the agents who are most suitable to take

the call.

Segment A target group which is created in the CPM database

and displayed as a directory in the Communication

Desktop (CDT) application. It contains persons,

contacts, and companies. Segments may be

company-wide (created in the CPM Administrator

application) or personal (created in the Task Manager

(TM) application).

SIP (Session Initiation Protocol) A standard protocol for audio, video, data, internet


SMS (systems management server) Microsoft Systems Management Server is a software

product for managing Windows computer systems

providing remote control, patch management, software

distribution, and hardware and software inventory.

SMS (short message service) A method for delivering short messages to mobile

phones.

SNMP (simple network management protocol) SNMP protocol forms part of the internet protocol suite

as defined by the Internet Engineering Task Force

(IETF) and is used in network management systems

to monitor network-attached devices for conditions

that warrant administrative attention.

SOAP (Simple Object Access Protocol) The method which allows to exchange data between

applications running on different platforms.

SPS (Smartphone Suite) An end user application related to mobile usage.

http://en.wikipedia.org/wiki/Server_%28computing%29

http://en.wikipedia.org/wiki/Operating_system

http://en.wikipedia.org/wiki/Direct-attached_storage


http://en.wikipedia.org/wiki/Internet_protocol_suite

http://en.wikipedia.org/wiki/Internet_Engineering_Task_Force

http://en.wikipedia.org/wiki/Network_management_systems

http://en.wikipedia.org/wiki/Network_monitoring

GLOSSARY

74


SQL (Structured Query Language) A programming language used for database queries

and updates. May also refer to a database server or

program.

Superior-assistant Roles related to special queue functions (previously

called boss-secretary).

Switchboard Traditionally hardware (a telephone routing table) for

routing calls and connecting calls to other users.

System Administrator An administration application related to the system

data and configuration.

T1, T1 line A single physical wire in telecommunications that can


conversations. It is widely used in USA and Canada.

The line data rate for T1 is 1.544 Mbit/s which is split

into time slots so a T1 line can carry 23 simultaneous

voice conversions.

TAPI (Telephony Application Programming Interface) A programming interface which allows to make

telephone and video calls by using computers.

Task Manager Extension for MS Office Outlook An extension application which makes it possible to

create tasks manually from e-mail messages.

TCP/IP (Transmission Control Protocol/Internet

Protocol)

A method and language for sending data between

computers on the Internet.

Telco Telco is a generic term for telephone companies

TFTP (trivial file transfer protocol) Trivial File Transfer Protocol (TFTP) is a very simple

file transfer protocol, with the functionality of a very

basic form of FTP

TM (Task Manager) An end user application related to task management.

It is also used for creating and maintaining customer

data and your personal segments.

User Administrator An administration application related to the user

accounts.

VLAN (virtual LAN) Virtual LAN, commonly known as a VLAN, is a group

of hosts with a common set of requirements that

communicate as if they were attached to the same

wire, regardless of their physical location.

Voicemail Traditionally a telephone answering service where

callers can leave messages into a voicemail box. Also

an application and functions in the Communication

Desktop (CDT) application.

VoIP (Voice over IP) A method and technology for transferring voice by

using an IP-based data network.

VPN (virtual private network) A method for offering remote users secure access to a

network.

VU (virtual unit) A group of technical services that are managed as a

single unit. Related to the system infrastructure.

VUA (virtual unit administrator) Tool for installing, upgrading and removing BCM

software.

VUMU (Virtual Unit Management Utility) An administration application related to the system

infrastructure.

WC (WebClient) A software object acting as an interface between an

user interface and a database.

WLAN (wireless local area network) A group of computing devices which are used over a

http://en.wikipedia.org/wiki/Telephone_company

http://en.wikipedia.org/wiki/Computer_file

http://en.wikipedia.org/wiki/Network_protocol

http://en.wikipedia.org/wiki/File_Transfer_Protocol

http://en.wikipedia.org/wiki/Local_area_network

GLOSSARY

75


wireless link within a limited geographical area.

WVP The core module required for the video call function in

the Communication Desktop (CDT) application. This


APPENDIX A: SAMPLE SAP CONTACT CENTER SERVERS

76

17 Appendix A: Sample SAP Contact Center Servers

17.1 Basic service provider setup using Windows Server 2008

The setup contains the following servers: - 1 SQL Server Cluster

- 2 SAP CCtr Application servers (+ 1 as Connection Server in DMZ if CMC is used)

- 1 SAP CCtr Reporting Server

SQL Server: - x86 cluster server with 1 or more CPUs

- 16 GB or more RAM

- 2 or more 100/1000 Base-T Ethernet ports per node

- Redundant (e.g. RAID 1 (2x15K drives)) 73 GB or more disk space for op.sys and applications per node

- Redundant (e.g. RAID 5 or 1+0 (15K hot pluggable drives)) 1 TB or more disk space for databases

- Redundant Power Supply

- Redundant ventilators

- Windows Server 2008 64-bit Enterprise edition (English recommended)

- SQL Server 2008 Standard 64-bit (English)

SAP Contact Center Reporting (SQL) server: - x86 server with 1 or more CPUs

- 8 GB or more RAM


- Redundant (e.g. RAID 1 (2x15K drives)) 73 GB or more disk space for op.sys and applications

- Redundant (e.g. RAID 5 or 1+0 (15K hot pluggable drives)) 146 GB or more disk space for databases


- Windows Server 2008 64-bit Standard edition (English recommended)


SAP Contact Center Application servers: - x86 server with 1 or more CPUs

- 4 GB or more RAM

- 2 100/1000 Base-T Ethernet ports per node

- Redundant (e.g. RAID 1 (2x15K drives)) 73 GB or more disk space



APPENDIX A: SAMPLE SAP CONTACT CENTER SERVERS

77

17.2 Service provider setup with SAN using Windows Server 2008

The setup contains the following servers: - 1 SQL Server Cluster (Can serve several SAP CCtr systems)

- 2 or more SAP CCtr Application servers (1 in core and 1 in access NW)

- 2 or more SAP CCtr failover Application servers (1 per NW, each can backup several application servers but usually only 1 at a time)

- 1 SAP CCtr Reporting Server

- 1 SAP CCtr Application server as Connection Server in the DMZ, if CMC is used (optional)

- 1 SAP CCtr Application server as Management server. (Can serve several SAP CCtr systems)

SQL Server: (SQL cluster is made of two or more of these) - x86 server with 1 or more CPUs

- 16 GB or more RAM


- Redundant (e.g. RAID 1 (2x15K drives)) 73 GB or more disk space for op.sys and applications per node

- 1 or more HBA (host bus adapter) for SAN connection and database storage


- Redundant ventilators

- Windows Server 2008 64-bit Enterprise edition (English recommended)


SAP Contact Center Reporting (SQL) server: - x86 server with 1 or more CPUs

- 8 GB or more RAM


- Redundant (e.g. RAID 1 (2x15K drives)) 73 GB or more disk space for op.sys and applications

- 1 or more HBA (host bus adapter) for SAN connection and database storage




SAP Contact Center Application servers: - x86 server with 1 or more CPUs

- 4 GB or more RAM

- 2 100/1000 Base-T Ethernet ports per node

- Redundant (e.g. RAID 1 (2x15K drives)) 73 GB or more disk space



SAP Contact Center 7 Infrastructure Overview · 2019-11-12 · SAP Contact Center infrastructure is...

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