Week Five Agenda Attendance Announcements Review Week Four Current Week Information Upcoming...

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Review Week Four

Designing an Enterprise CampusThe Enterprise Campus is the foundation for delivering

the applications, services, and user requirements.

Network application characteristics (requirements)

Organizational requirements

Services

Applications

Environment characteristics (requirements)

Geography

Transmission media

Infrastructure device characteristics (requirements)

High availability

High throughput

Network Application Characteristics

Peer-Peer ApplicationsThe peer-peer applications are designed with the

majority of users in mind. It is likely to be most heavily traffic path from one network edge device to another through the organizational network.

Instant messagingIP phone calls (strict network

requirements for QoS)File sharingVideoconferencing systems

(requirements similar to IP phone QoS)


Quality of Service (QoS)

A set of metrics used to measure the quality of transmission and service availability of any given transmission system.


Client-Local Server Applications

80/20 Workgroup Rule

Because the traffic on corporate networks has typically increased, it has resulted in more

isolated segments. These isolated segments resemble departments within a corporate structure, where segments have their own local servers, users, and applications. This design configuration usually has the local servers and users in the same VLAN. The traffic leaving the network segment will connect to the campus backbone to connect to other VLANs or destinations.


Client-Server Farm ApplicationsLarge organizations require their users to have fast, and reliable access to critical applications. Today, banks, state, and other governmental organizations needed this access in order to

verify and maintain the integrity of individuals. Because of this high accountability requirement, high-performance multilayer switches are

implemented, increased network bandwidth, and locating the servers in a central location rather than a workgroup has been achievable due to scale of economies. These configurations require high-end LAN switches connected to the fastest LAN technologies, such as Gigabit Ethernet.


Client-Server Farm Applications

20/80 Rule

Server farms include the following:

Organizational mail servers (Microsoft Exchange)

File servers (Microsoft and Sun)

Database servers (Oracle)


Client-Enterprise Edge Application

The Enterprise Edge application is used to transmit data between the organization and its public servers. Data transmission exchange can come from web based technologies, external mail, and DNS servers.

Communications with these servers is crucial, because two-way replication of data. In order

to sustain this high accountability, redundancy and security are the most important requirements for these applications.

Network Application CharacteristicsClient-Enterprise Edge Application

Connectivity has increased the use of LAN switching at Layer 2. LAN switching has resulted in increased performance and more bandwidth for specific applications requirements of new organizational applications.

Throughput is the average rate of successful message delivery over a communication channel. This data may be delivered over a physical link, and/or pass through a certain network node. The throughput is usually measured in bits per second (bit/s or bps), and sometimes in data packets per second or data packets per time slot. Throughput varies between user workgroups and high capacity links to servers, and/or server farms.


Client-Enterprise Edge Application

High Availability is a function of the application and the entire network between the client

workstation and server(s) located in the network.

Summary

Project costs are driven by it’s size and applications used. If your implementing a peer-peer environment, normally the cost will be low. If your designing a network with redundancy and with high end application(s), your costs will be significantly higher. The types of applications used will also raise the cost

Environment CharacteristicsEnvironmental characteristics play a significant role in determining the location of the Enterprise Campus, the distance between buildings, the size and shapes of the buildings, and which technology to use to maximize the organizations investment.

Normally, the distance between nodes and their locations within an Enterprise Campus drive the type of technology utilized. In addition to the node (s) proximity, organizational requirements also influence the type of technology to be used.

Environment Characteristics

Intrabuilding campus network structure provides connectivity for all terminating nodes located in the same building and provides external access to network

resources. The Building Access and Building Distribution layers are located in the same building.

User workstations are usually connected to the Building Access switches in the floor wiring closet with twisted-pair copper cable. Wireless technology can also be used to provide connectivity within the building and/or between buildings without the use of UTP and cables.

WLAN was developed because of the demand for LAN connections over the air waves in intrabuilding environments.

Environment CharacteristicsStructural considerations within the network geography

The access layer switches connect to the Building Distribution switches over optical fiber.

This building configuration could have a compressed hierarchical network where the Building Distribution switches and Campus Core switches are combined.


Interbuilding characterics is where there are two or more individual buildings connected to each

other. These buildings could have the same configuration (compressed hierarchical network) or contain only the Building Access layer. The distance between buildings is within close proximity, typically within a few hundred meters to a few kilometers apart. The medium used to interconnect campus buildings is normally customer owned, high-speed optical fiber.


A distant remote building is when the buildings exceed more than a few kilometers, but are in

the same metropolitan area. For this situation, the physical media is the most important factor.

The speed and cost are directly related to the media selection.Some companies own their own media, like

copper lines , or fiber. However, if they do not have the connectivity to their remote locations, the Enterprise Campus must connect through the Enterprise edge using connectivity options from public service providers, such as WAN links or Metro Ethernet.


The service level agreement (SLA) and the risk of downtime must be addressed if inexpensive and unreliable links are used. Mission critical application(s) demand fast-speed links and high-reliability connections.

Enterprise Campus Device ConnectivityAn Enterprise Campus can use a variety of different physical media to connect to their devices. The type of media used will normally set the precedence for the next 10 years. The cost of the media should be inline with the companies budget, and the technical requirements that would influence signal attenuation and electromagnetic interference.

Transmission Media

Copper: Twisted-pair cable of four pairs of isolated wires that are wrapped together in plastic cable.

Category 5, and 5e for greater speeds of 100 megabits (Mbps) or higher

Category 6 is recommended for Gigabit Ethernet.

Because of the possibility of signal attenuation in wires, the maximum cable length is usually 100 meters.

Transmission MediaSignal attenuation affects the propagation of waves and signals in electrical circuits, in optical fibers, as well as in air (radio waves). It is a damping affect on the original signal strength.

Distances greater than 100 meters may require Long-Reach Ethernet (LRE). LRE is a Cisco proprietary technology that runs on voice grade copper wire, and it accommodates the greater distance to access the technologies in WANs.

Transmission MediaDifferent types of fiber

Multimode (MM) fiber carries multiple light waves or modes concurrently, each

at a slightly different reflective angle within the optical fiber core. Because modes

tends to spread out over longer lengths, multimode fiber is used for shorter

distances. The diameter of multimode fiber is 50 to 62.5 micrometers.

Transmission MediaDifferent types of fiber

Single-mode (SM) fiber carries a single wave (laser) of light. The diameter of a single-mode fiber is 2 to 10 micrometers. Single-mode fiber preserves the dispersion and loss of light, and therefore is used for distant transmissions. SM

is an excellent solution for future high-speed connectivity.

In summary, optical fiber is used where the transmission distance exceeds 100 meters and immunity to electromagnetic interference is required.

Transmission MediaWireless is also referred to as a radio receiver. The term refers to without cables or cords, chiefly using radio frequencies and inferred rays.

WLAN are useful when it comes to extending an existing network or replacing a traditional cabled network.

Inside buildings, the WLAN equipment includes an access point (AP), which acts similar to a wired hub, and PC client adapter.

Transmission MediaIEEE Standards

802.11g allow speeds up to 54 Mbps in the 2.4 GHz band over a range of 100 feet.

802.11b supports speeds up to 11 Mbps in the 2.4 GHz band.

802.11a supports speeds up to 54Mbps in the 5 GHz band.

See chart on page 233 in your Designing for Cisco Internetwork Solutions (DESIGN) text.

Infrastructure Device CharacteristicsToday, most network end users are connected using switched technology and not shared media segment. The benefits of switched technology are dedicated network bandwidth for each device on the network. Switched networks also support infrastructure services, like QoS, security, and network management.LAN switches in the recent past were for Layer 2 devices. Now, Layer 2 switching supports multiple simultaneous frame flows. Multilayer switching performs packet switching and several functions at Layer 3 and higher up in the OSI layers. The technology is moving in the direction of replacing routers in the LAN switched environment.

Infrastructure Device CharacteristicsDifferences between Layer 2 and Multilayer

Switching

Multilayer switching provides different information inside the frame to determine the correct output interface.

Multilayer switching forwards frames based on network layer information rather than MAC address.

Multilayer switching is a hardware based switching and routing integrated into a single platform.

Infrastructure Device CharacteristicsIP Multicast

IP multicast technology is a way to sending one data stream to multiple end users and maintain required bandwidth. The data stream is sent from one source, and replicated for the registered users at the destination.

Class D IP address ranges from 224.0.0.0 to 239.255.255.255.

Cisco Protocols for Routers and HostsInternet Group Management Protocol (IGMP)

The IGMP protocol is used between the router and the registered hosts intended to receive multicast data. The hosts notify the router to join or leave a specific multicast group.

Cisco Group Management Protocol (CGMP)

The CGMP protocol is used by switches and routers. The router informs the switches directly connected to them about the IGMP registration(s) from it’s hosts to receive multicast data stream.

Cisco Protocols for Routers and HostsInternet Control Message Protocol (ICMP) is

used by IP for many different services. ICMP is a management protocol and messaging service provider for IP. Its messages are carried as IP datagram's.

QoS ConsiderationsClassification and marking

Packet classification – partitioning traffic into multiple priority levels, or class of service

Marking – changing the frame priority or class of service

Congestion management

Queuing – separating traffic into different queues. The marking inside the frame or packet is used to determine which queue

Scheduling – is used to determine the order in which the queues are serviced

QoS ConsiderationsPolicing and shaping is a process of identifying

violations of threshold levels and reduces a stream of data to a predetermined rate or level. Traffic shaping buffers the frames for a short period of time. Policing drops or lowers the priority of the frame in violation.

Traditional WAN Technologies

Introduction to WANsA wide area network (WAN) is a computer network that covers a broad area. Typically, it is any network whose communications links cross metropolitan, regional, or national boundaries. WAN transmission facilities are generally provided by service providers (SP), such as telephone companies.

Service provides charge for the switching and connectivity they provide. This charge is called a tariff, for the services provided by the WAN.

WAN Connection TypesConnecting LANs together over a data communications

equipment (DCE) network

Dedicated WANs utilize synchronous serial connections.

Circuit-switched WANs use telephone company networks with asynchronous serial, and ISDN.

Packet-switched WANs use a service provider with synchronous serial.

WAN Connection TypesLeased lines are typically point-to-point connections or a dedicated connection. The WAN connection path from the CPE, through the DCE switch, to the CPE of the remote site, allowing DTE to communicate at any time with no setup procedures before transmitting data. It uses synchronous serial lines up to 45 Mbps.

Time Division Multiplexing (TDM) is a technique for assigning bandwidth on a single wire, based on pre-assigned time slots, to data from several channels. Bandwidth is allocated to each channel regardless of a station’s ability to send data. Drawing

WAN Connection TypesCircuit-switching sets up a line like a phone call. No data can transfer before the end-to-end connection is established. Circuit switching uses dial-up modems and ISDN. It is used for low-bandwidth data transfers.

WAN Connection TypesPacket switching is a WAN switching method that allows you to share bandwidth with other companies to save money. Packet switching is excellent for bur sty data transfers, packet switching can save you money. However, if you have constant data transfers, you will need a leased line. Frame relay and X.25 are packet-switching technologies . Speeds can range from 56Kbps to 2.048Mbps.

WAN ProtocolsPoint-to-Point Protocol (PPP) is an industry standard protocol. PPP can be used to create point-to-point links between different vendors’ equipment. It allows authentication and multilink connections and can be run over asynchronous and synchronous links.

Asynchronous Transfer Mode (ATM) was created for time sensitive traffic, providing simultaneous transmission of voice, video, and data. ATM uses cells rather than packets that are a fixed 53-bytes long.

WAN ProtocolsHigh-Level Data Link Control (HDLC) was derived from Synchronous Data Link Control (SDLC), which was created by IBM as a Data Link layer connection protocol. HDLC is a connection-oriented protocol at the Data Link layer. HDLC was not intended to encapsulate multiple Network layer protocols across the same link. The HDLC header carries no identification of the type of protocol being carried inside the HDLC encapsulation. Because of this, each vendor that uses HDLC has their own way of identifying the Network layer protocol, which means that each vendor’s HDLC is proprietary for their equipment.

WAN Protocols Link Access Procedure, Balanced (LAPB) was

created to be used as a connection-oriented protocol at the Data Link layer for use with X.25. It can be used as a simple Data Link transport. LAPB has a tremendous amount of overhead because of its strict timeout and windowing techniques. You can use LAPB instead of the lower-overhead HDLC if your link is very error prone.

WAN Protocols Integrated Services Digital Network (ISDN) is a set of

digital services that transmit voice and data over existing phone lines. ISDN can offer a cost-effective solution for remote users who need a higher speed connection that analog dial-up links offer. ISDN is also a good choice as a backup link for other links.

ISDN allows voice and data to be transmitted simultaneously across the world using end-to-end digital connectivity. In addition, it offers increased bandwidth, reduced call setup time, reduced latency, and lower signal-to-noise ratios, compared to analog dialup.

WAN Protocols Frame Relay is a packet-switched technology that has

been around since the 1980s. Frame Relay is an industry standard networking protocol that handles multiple virtual circuits (VC) using a derivation of HDLC encapsulation between connecting devices. Frame Relay is a Data Link and Physical layer specification that provides high performance. Frame relay typically can run at speeds of 64Kbps to 1.544Mbps. Frame Relay provides features for dynamic bandwidth allocation and congestion control.

WAN Protocols Multiprotocol Label Switching (MPLS) replaces the

hop-by-hop, individually routed packet model with a connection-oriented model that establishes ‘paths’ to destinations. Instead of routing each packet based upon its destination address, each packet is labeled such that it can be switched along a pre-defined path. In addition, MPLS defines traffic engineering methods that enables these paths to have associated quality-of-service attributes. Thus, a single destination may have multiple paths leading to it, with one path used for voice, one for video, and one for data.

WAN Protocols Which WAN service is the best one to use?

Answer: None of them. The best WAN service is the one you can get in your neighborhood or at your company. Since you don’t have many options to choose from, call your local service provider and ask what they can provide to you.

Transmission Modes For digital transmission, all information is converted

into binary codes of 0 and 1 for transmission. It is necessary to notify the other end of precise information such as where the data starts and how long the interval of data is.

“Synchronous”and“asynchronous”are the two modes for communicating this information, and it is necessary to confirm which mode each end supports. With Synchronous Transmission Mode, 64 kbps is the highest available transmission speed, while 57.6 kbps is the highest for Asynchronous Transmission Mode.

Transmission ModesSynchronous signals, signals that play the role of signs, are added to the top of the data to be transmitted. With these signals, computers can precisely determine the first position of the characters. This mode can transmit data accurately, making it appropriate for corporate information networks.

Asynchronous signals, instead, use a portion of the data that has arrived as a clue, the first position of the character is identified. Two bits are added to each character, a start bit for the beginning and an end bit for the end, making the transmission speed slower.

Packet-Switched Network TopologiesStar topology is a LAN physical topology with endpoints on the network converging at a common central switch (known as a hub) using point-to-point links. A logical ring topology can be configurated as a physical star topology using a unidirectional closed-loop star rather than point-to-point links. That is, connections within the hub are arranged in an internal ring.

Full mesh topology is where every node has either a physical or a virtual circuit linking it to every other network node. A full mesh supplies a great deal of redundancy but is typically reserved for network backbones because of its expense.

Packet-Switched Network TopologiesPartially meshed topology is where some network nodes form a full mesh, but others are attached to only one or two nodes in the network.

Observe the WAN Transport Technology table on pages 298 and 299 in your text book.

WAN Transport TechnologiesDS0 Rate is known as the base channel bandwidth of 64Kbps. A bandwidth of 64Kbps is the bandwidth required for an uncompressed digitized phone conversation.

Standard speech less then 4KHz; analog speech is filtered at 4KHz before being sampled.

Nyquist Theorem sample at a rate at least two times the input frequency to obtain a signal that represents the true signal.

Each sample is encoded into 8 bit octets. This DS0 rate is 8KHz. Per second times 8 bits per sample, which is 64Kbps.

TechnologiesMetro Ethernet technology is based on Ethernet technology to offer the best cost-effective, high speed connectivity for MAN and WAN.

DSL technology is a high-bandwidth technology over the traditional copper lines. It is designed to work with two modems at either end of the wire. DSL is a transmission technology that is used by SPs to deliver a wide range of services to subscribers.

Asymmetric DSL (ADSL) used over short distances (less then 2Lmeters). Most common type used. Frequency range 100KHz to 1.1Hz. ADSL allows PSTN tetphone service concurrently on the same line.

TechnologiesSymmetric (SDSL) DSL allows traffic to be transmitted in both directions at the same speed over a single twisted pair. The distance served with SDSL is 10K feet or 3048.8 meters. SDSL is often referred to as single-pair DSL. SDSL is excellent for running applications like email and web servers.

Long Reach Ethernet (LRE) is a WAN access technology which allows for greater distance than the traditional Ethernet provides.

Cable technology is another high-speed copper platform that supports both analog and digital video services over a coaxial cable.

TechnologiesCabling technology makes use of channels for upstream and downstream data flow. One application channel in the coaxial cable is used to upstream signals from the modem to the Cable Modem Termination System (CMTS). The output from the CMTS is handed to either the WAN or the PSTN. A different channel is used for the downstream signals from these Internet Service Providers to the CMTS to the modem.

The CMTS converts signals from the modem to IP packets prior to handing them to the IP router for transmission across the Internet. Downstream signals are modulated for transmission across the cable to the modem.

TechnologiesInternet download bandwidth over a cable TV line is shared 27 Mbps.

Internet upstream bandwidth over the same shared cable is 2.5 Mbps.

Wireless technology electromagnetic waves carry RF signals. It is the option of some, that these waves could be harmful to humans.

Synchronous Optical Network/Digital Hierarchy (SONET/SDH) is the ANSI standard for synchronous transmission on fiber optic media. It specifies a base signal rate of 51,84 Mbps and a set of multiples of that rate, known as Optical Carrier levels, up to 2.5 Gbps.

TechnologiesSONET/SDH is a circuit based technology that provided uses high speed circuits using TDM framing.

Dark fiber is a fiber optic cable(s) leased from an SP. Fiber is typically connected to a company’s own infrastructure. Dark fiber got its name after the dot-com burst. Many of the companies that had the rights to these fiber networks either went bankrupt, or, had to abandon their goals of utilizing this fiber. This resulted in hundreds of thousands of miles of “unlit” (dark) fiber. Dark fiber is optical fiber that is lying in the ground unutilized

WAN DesignThe network designer should design the Enterprise Edge based on the PPDIOO methodology.

Analyzing customer requirements

Characterizing the existing network and sites.

Designing the network topology and solutions.

Observe the WAN Physical Media Bandwidths table in your text book on page 320.

WAN Bandwidth OptimizationCompression is used to reduce the data size to conserve transmission time.

Upcoming AssignmentsAssignment 5-1, Concept Question 4 is due October 13,

2010

Assignment 4-1-2, Basic Routing and LAN Switching Configuration is due November 10, 2010

Assignment 4-1-3, Basic Network Troubleshooting is due November 24, 2010

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