QoE White Paper

8/12/2019 QoE White Paper

http://slidepdf.com/reader/full/qoe-white-paper 1/18/N 915-2304-01 Rev A March 2009

Active Quality of

Experience Verification for

Multiplay Services with IxRave


http://slidepdf.com/reader/full/qoe-white-paper 2/18



Contentsntroduction ............................................................................................. 2

Defining Quality ........................................................................................ 2

ITU Definition of QoE ..........................................................................................3

ITU Definition of QoS ..........................................................................................3

ITU Definitions of QoE in IPTV Networks ................................................................ 4

Application Factors Affecting Video Quality........................................................... 5

Characteristics of Multiplay Transport Network ......................................... 6

ntroducing IxRave .................................................................................... 9

Using IxRave for Pre-deployment Network Assessment and Service Turn-Up .............11

Using IxRave for Fault Isolation ..........................................................................12

Using IxRave for Ongoing Active Monitoring .......................................................13

Using IxRave for Service Level Agreements ..........................................................14

Conclusions ............................................................................................. 15



IntroductionIn today’s competitive service provider environment, offering an array of Internet-based service

is a business prerequisite. Content services such as social networking and gaming may come a

go, but the core multiplay services of broadband Internet access, carrier-grade telephony andbroadcast-quality television remain the rule.

Consumers’ quality expectations have been set high from using legacy voice and video system

These quality expectations represent a new challenge for service providers, since previous mul

play requirements were not as clearly defined.

This white paper addresses the definition of customer quality of experience (QoE) for IP-based

media services, including:

• How it is it measured?

• How can service providers prepare their networks for the demands of newer services?• What “best practices” should service providers implement to provide customer satisfactio

IP networks differ from the Legacy networks they’re replacing. The fundamentals of IP network

construction and the dynamic nature of today’s commercial infrastructure cause inevitable cong

tion. Congestion is the source of many quality problems in multiplay networks. Network opera

can partition network resources based on policy goals by implementing quality of service (QoS

mechanisms, but good QoS at the network level does not ensure good QoE.

Ixia’s IxRave is a service verification solution that uses “active monitoring” -- a critical tool for

operators trying to meet customers’ high QoE expectations. It ensures network service delivery

by actively testing individual subscriber paths, rather than passively monitoring and reporting ogeneral network conditions.

Defining Quality Quality means different things to different people. Quality must be clearly defined in order for

service providers to address their customers’ needs. What is quality, and how is it measured?

Standards bodies such as the International Telecommunications Union (ITU) put great effort into

creating metrics that define multiplay quality. The ITU measures multiplay network quality using

QoE and QoS.

The fundamentals of IPnetwork constructionand the dynamic natureof today’s commercialinfrastructure causeinevitable congestion.



TU Definition of QoE

nternational standards bodies recognize the need for consistency in the definition of QoE. The

TU, in particular, took a leading role in defining quality standards for advanced media services.

heir standard P.10/G100 provides the following definition of QoE:

The overall acceptability of an application or service, as perceived subjectively by the

end-user.

NOTE 1 – Quality of Experience includes the complete end-to-end system effects (client,

terminal, network, services infrastructure, etc.).

NOTE 2 – Overall acceptability may be influenced by user expectations and context.

ince they include the subjective user experience in the definition of QoE, the ITU defined a test

methodology based on mean opinion scores (MOS). A MOS is measured by carefully controlledubjective tests laid out in ITU-R BT.500-11 and ITU-T P.800. In these tests subjects listen to video

r telephony, and rate them on a scale from 1 to 5. The average ratings from to each test case

ield the MOS.

Understanding network QoE means weighing subscriber satisfaction with the end-to-end system,

long with the content and the operator support system (OSS).

TU Definition of QoS

QoS is a concept closely related to QoE; the two are often confused. The ITU’s E.800 standardives the definition for QoS as:

he collective effect of performance which determines the degree of satisfaction of a user of the

ervice.

n telecommunications, QoS measures a network’s actual performance using two factors: QoS

mechanisms and QoS metrics.

QoS mechanisms such as traffic schedulers, shapers and admission control techniques help

mooth out traffic flows. These mechanisms ensure that no one user or application gets an unfair

hare of the available bandwidth. One such mechanism is the multi protocol label switching

MPLS) protocol, which is at the core of many multiservice IP networks. MPLS uses a number of

ophisticated admission control and traffic management features to control traffic flows.

Understanding network Qo

means weighing subscribersatisfaction with the end-to-end system, along withthe content and the operatsupport system (OSS).



In IPTV networks, loss concealment protocols such as forward error correction (FEC) or automa

repeat request (ARQ) are commonly used QoS mechanisms. More common QoS metrics and

measurements such as packet loss, network latency, and jitter also help determine the underlyi

quality of the transmission network.

ITU Definitions of QoE in IPTV Networks

As discussed above, the subjective nature of QoE requires polling user opinions. Fortunately,

the industry’s long experience surveying voice over IP (VoIP) networks under a variety of impai

ments produced a strong correlation between polled MOS and network QoS metrics. This mea

a highly accurate MOS can be calculated for a network with given packet loss, delay, and jitte

QoS metrics. Network operators predict user voice call quality over the network by using QoS

metrics.

Unfortunately, video streams are more difficult to manage. IP network video packetization and

transmission algorithms compress a tremendous amount of content into small IP packets. In IPTV

networks, the loss of a single key packet can cause noticeable video degradation. The upshot

that making predictions about the effect of a given set of QoS metrics on the service can be ve

difficult.

ITU’s standard G.1080, “Quality of Experience Requirements for IPTV Services,” explains the

elements of QoE for IPTV. Figure 1 shows the framework described in the document. It depicts

network QoS metrics, includes attributes of video applications and characteristics of the specifi

video compression algorithms.

QoE

QoS Human Components

ServiceFactorsService

Availibility

TransportFactorsDelay Loss

Latency

Objective Subjective

ApplicationFactors

Video Codec Join Leave Latency

Emotion Experience

Figure 1. ITU Definition of QoE in G.1080

The industry’s longexperience surveyingvoice over IP (VoIP)networks under a varietyof impairments produced astrong correlation betweenpolled MOS and networkQoS metrics.



Application Factors Affecting Video Quality

Content providers who transport digitized and packetized video signals over an IP network have

myriad of options. At best, an experienced analyst matches the capabilities of the transport

etwork and the parameters of the compression algorithm so that the result meets a particularubscriber base’s expectations.

Often the content provider sets the video encoding, and the network operator simply accepts

. The selected compression algorithm parameters drives the underlying network’s QoS metrics

equirements (such as packet loss, delay and jitter), as recommended by the ITU in the G.1080

tandard.

acketization encoder input comes from different source video stream variants such as Europe’s

phase alternating line (PAL) and the United States’ National Television Standards Committee

NTSC). The input can also have varying definition levels, such as standard definition (SD) or high

efinition (HD). Signal coding comes with a variety of algorithms, such as those defined by the

Moving Pictures Expert Group (MPEG). Earlier digital cable systems often used the MPEG-2 proto-

ol, while new IPTV systems use the more advanced MPEG-4 algorithm and its variants. A network

perator might deliver streams in multiple encoding formats.

Different algorithms deliver video at a variety of bit rates. Bit rate, along with the compression

lgorithm, are key in the faithful reproduction of the original signal on the target device. The

packet stream is output in its natural variable rate format or with a constant bit rate (CBR), which

elps network providers engineer their transport networks.

Content providers optimize the output packet stream using a number of tools in addition to con-tant or variable bit rate and base algorithm. Pre-processing algorithms remove unwanted noise

rom the input signal before it is encoded. The group of pictures (GOP) algorithm controls the

ompression of video picture information into a series of data packets, and the handling of motion

between successive video frames. Control setting management often defines the competitive

dvantage of one encoding system versus another.

TU’s G.1080 standard gives recommendations for the underlying network QoS metrics for a

iven type of encoding and bit rate. Table 1 gives an example for standard definition television

SDTV).

ITU’s G.1080 standardgives recommendations fo

the underlying networkQoS metrics for a giventype of encoding and bitrate.



TransportStreamBit Rate(Mbit/s)

Latency JitterMax Dura-tion of a

Single Error

Correspond-ing Loss

Period in IPPackets

LossDistance

Corresponing Avera

IP VideoStream

Packet Lo

Rate

3.0 < 200ms < 50ms <= 16ms 6 IP packets1 error eventper hour

<= 5.85E-06


<= 5.46E-06


<= 5.26-06

Table 1. Recommended Minimum Transport Layer Parameters for Satisfactory QoE for MPEG

Encoded SDTV Services

Characteristics of Multiplay Transport Network Multiplay service networks have come a long way since the initial wave of broadband service

For one thing, the penetration of new optical transport technology greatly increased the bandw

available to the Internet. This is true not only in the central core of operator networks, but in ag

gation and access networks as well. Fiber to the home (FTTH) is one of the fastest growing acc

technologies, poised to unleash massive amounts of bandwidth directly to consumers’ homes.

The stabilization and adoption of MPLS as the de-facto architecture for core networks provides

vice providers with new traffic management capabilities. Some operators are using carrier Eth

technology to implement aggregation networks that connect access systems to core networks.

Operators partition network resources using sophisticated QoS mechanisms so that streaming

video and peer-to-peer file sharing applications do not adversely impact voice services. Opera

can also allocate specific bandwidth to IPTV streams. Some believe the increased amount of hi

quality fiber-based bandwidth and ubiquitous usage of QoS mechanisms obviates most concer

about subscriber QoE.

Unfortunately, this is not true. The main impediments to high subscriber QoE are:

• The inherent structure of IP networks and their building blocks cause network congestion

always occur, regardless of the speed of the connecting telecommunications facilities.

•

It is prohibitively expensive to engineer an IP infrastructure that handles the large ratiosbetween peak and mean traffic caused by extraordinary events.

• Deviations from a network’s planned implementation are inevitable due to the dynamic

nature of IP networks, which includes equipment failures, line faults, software upgrades,

hardware evolution, and human error.



igure 2 shows some of the typical building blocks in IP networks, and illustrates how congestion

an occur even as speeds increase.

Frame Relay Networks PSTN/ISDN

Radio AccessNetworks

ATMNetworks

Wireless Access

Between Networks

IP/MPLSNetworks

EthernetNetworks

MU

MU

MU

MU

MU

MU

MU

MU

MU

Speed Mismatch

Aggregation

Errors and Anomolous Behavior

Within Networks

?

Figure 2. IP Network Building Block with Inherent Congestion Possibilities

Congestion happens within a given operator network, between sub-networks of different technolo-

ies within a given operator network, or between the network domains of different operators who

ollaborate on the delivery of advanced content based services.

or example, traffic from a core network based on a 40 gigabit fiber optic service is routed onto

local area network based on 10 gigabit Ethernet links. The speed mismatch can cause conges-on and packet loss even though both are high speed services. Routers supporting switching

between multiple high-speed links of the same speed can manifest similar problems – for example,

when employing such technologies as aggregated links.

xceptionally high traffic exacerbates these issues. Figure 3 shows a graph of the incoming call

ate, CPU utilization and congestion statistics for a VoIP softswitch during a New Year’s Eve peak

alling event.



Figure 3. Large Peak-to-Mean Ratios in Multiplay Services

Providing support for short traffic bursts by building out server and network infrastructure is usu

too expensive for service providers. Operators must anticipate network congestion by testing th

network under heavy load conditions. Congestion must be handled gracefully, servers and netw

infrastructure shouldn’t malfunction under the load, and any subscribers admitted to the serviceshould receive a reasonable service despite the overload.

Finally, inevitable change is one of the most important characteristics of multiplay transport net-

works. IP networks are very dynamic compared to their legacy counterparts, such as the public

switched telephone networks and radio frequency-based television distribution.

For example, the consequences of transmission faults and equipment failures are different for IP

networks and legacy networks. Legacy networks have a simpler hierarchical design and suppo

a single application, making it easier to predict the effects of a given failure. IP networks are

designed to be “resilient,” and when faults occur traffic is rerouted. Rerouting traffic keeps theservice available, but creates unpredictable loads and causes changes in application performa

and function.

Operators must anticipatenetwork congestion bytesting the network underheavy load conditions.



ince software drives IP networks, the upgrade path to newer and faster hardware is quicker than

n legacy networks. The distributed nature of IP networks also means more network components.

oth factors create a need for network management and monitoring.

he large variety of applications supported on IP-based multiplay networks contributes to the net-

work’s dynamic nature as subscribers adopt new services. Increasing amounts of HDTV and user

enerated video content can quickly change network requirements, for example.

Current network management systems were developed to meet the requirements of the first phase

f broadband network deployments. Today’s dynamic and demanding multiplay environment

equire new tools to manage and regulate traffic.

he majority of systems currently deployed exclusively use passive monitoring technologies,

which often employ expensive probes at numerous points in the network. Exclusive use of passive

monitoring can give a malfunctioning network a clean bill of health, even while support person-

el busily help large numbers of disgruntled customers. Passive network management systemsan overlook an issue’s root cause, even as network management tools light up with hundreds of

larms.

ntroducing IxRavexia designed the IxRave service verification solution specifically for modern network environments.

s patented methodology was developed in cooperation with tier 1 network operators, providing

ubscribers with a high level of QoE from an actively tested network infrastructure.

xia’s IxRave software is based on Ixia’s proven and industry-leading test tools -- the same equip-

ment used by manufacturers and service providers developing and testing current multiservice

nfrastructures.

xRave runs on actual subscriber network paths using pre-designed tests from a centralized “test

ead.” IxRave monitors the network infrastructure from typical locations, and enables service per-

onnel to run active tests on an individual subscriber’s service path

igure 4 shows examples of IxRave deployments.

Ixia’s IxRave softwareis based on Ixia’sproven and industry-

leading test tools – thesame equipment usedby manufacturersand service providersdeveloping and testingcurrent multiserviceinfrastructures.



Figure 4. Typical IxRave Deployments

IxRave tests the entire network infrastructure and verifies that it meets the ITU defined goals for

QoS and QoE by using both passive monitoring and active testing. Three active test paths are

used:

• End-to-end

• Testing in from the access network, and

• Testing out from the access network.

IxRave sends different permutations of multiplay traffic, such as voice and video, down subscri

paths and checks that they meet QoS standards. It tests the network under load conditions and

measures how it performs during peak activity times. IxRave then makes network health assess

ments based on the defined QoE and QoS metrics set by the network provider.

IxRave tests the transport, network and service layers of the network, as well as more common

QoS metrics such as delay, jitter and packet loss. It measures the customer’s QoE using MOS a

defined by the ITU. Using IxRave, the network provider gets a true end-to-end picture of the network, and “sees what the customer sees.”

Active test points can be useful at administrative borders or between content providers and net

work providers in IPTV networks, and help when the core network and the access network are

by different administrative entities.

Enterprise VPNs

Core Network

Wireless Voice/Dataand Backhaul

Wireline Triple Play DSL/CATV/FTTH

AggregationNetwork

DSLAM/CMTS/ONT

BSC/Node Bs/SGSNs MSC, GMSCGGSN, PDSN, B-RAS RADIUS,

DNS, DHCP etc

Triple Play ServiIxRave Server

Scheduled Tests

SLA andHealth ReportsCentralized Test Head

Ixia Chassis

Tier 1, 2 or 3Service Personnel

SMS Access



xRave test points can also create precise demarcation points for the implementation and veri-

cation of service level agreements (SLAs), commonly found in IP virtual private network (VPN)

ervices. Figure 4 shows typical locations for IxRave’s unique, inexpensive active test points.

xRave integrates with the operator’s OSS and creates “hairpin” loopbacks. IxRave then isolates

problems from the centralized test head by checking each segment in the customer path, as well

s the supporting application infrastructure, as shown in Figure 5.

Figure 5. IxRave uses “hairpin” turns to diagnose network issues

With this approach, an operator tests the subscriber infrastructure without the expense of putting

ostly non-IxRave probes at every access network concentrator site.

xRave’s active testing methodology demonstrably brings the best results when delivering multiplay

ervices. Operators implementing IxRave report lower operations expense and higher customeratisfaction. This lowers CAPEX and leaves the smallest service assurance testing footprint in the

ndustry.

Using IxRave for Pre-deployment Network Assessment and Service

Turn-Up

ervice-oriented networks consist of complex suites of application, networking, operational

nd administrative equipment. Networks evolve constantly due to subscriber loads and service

mix. A network operator must know whether the infrastructure meets customer QoE and QoSxpectations:

• At the commencement of new service offerings,

• Before and after changes in topology, and

• In anticipation of specific public events that may provide exceptional load on the system.

STB

CPE

DSLAM accesshairpin from chassis

to customer PVC/VLAN

DSLAMManagement System

TEST PVC

ISP Service Platform

DSLAM

BRAS

Backbone

IxRave Server

IXIA Chassis



IxRave runs a series of customer experience tests on newly installed or updated infrastructure.

Scheduled active monitoring verifies service impact before and after network or topology reco

figurations such a node splits. Operator’s can catch configuration and management issues befo

their customers notice problems. IxRave stores results in an easily accessible test history databa

establishing a baseline for “normal” network activity.

Operators bringing a new consumer or business customer online must know if the network’s ca

ity will deliver satisfactory service. Satisfactory service includes testing not only the transmissio

and routing resources of the network, but the customer’s application, billing, and support requ

ments as well. With the click of a mouse, IxRave simulates new customer service turn ups, and

calculates the impact on network resources.

IxRave evaluates the infrastructure’s new customer support readiness with “go/no-go” metrics.

Operates can fix problems or add needed capacity using the captured supporting data in a “n

go” situation. IxRave verifies new customers’ satisfaction by testing the service delivery capaci

and performance by specific infrastructure elements. The resulting performance figures establis

baseline for evaluating future service issues.

According to research, satisfaction issues usually occur during a service deployment’s first few

weeks. IxRave places newly activated customers into an active testing “hot list,” which checks t

service path during the initial trial period. Should an issue arise, active monitoring addresses c

tomer concerns by providing complete customer data. IxRave ensures the operator that the syst

is “ready for business.”

Typical multiservice networks operate under a variety of load conditions. They must absorb ma

times their typical load during special events (such as during the Olympic Games or on MotheDay). IxRave tests the performance of key links in the supporting aggregation and core networ

as well as application, operational, and administrative systems, under various load conditions

Using IxRave for Fault Isolation

IxRave’s strong differentiator is first-level fault isolation. Expensive and frustrating solutions suc

as power-cycling a modem, changing a DSLAM port, or replacing a CPE often yield no results

IxRave validates the customer’s infrastructure during a help desk call using a series of tests. IxR

handles service issues efficiently by providing simple pass/fail results and suggested solutions.

By integrating with the provider’s OSS, IxRave creates “hairpin” loopbacks. The loopbacks tra

verses the entire customer path and analyzes each path segments. The centralized test head ca

then isolate any problems in either the customer path or the supporting application infrastructu

as shown in Figure 5.

Satisfactory service

includes testing not only the

transmission and routing

resources of the network, but

the customer’s application,

billing, and support

requirements as well.



xRave’s has a remarkably quick return on investment (ROI) that comes from a reduction of unnec-

ssary equipment swaps -- equipment that is often fully functional.

upport personnel often dispatch service technicians to examine customer wiring and CPE when

hey can’t resolve a problem. IxRave drastically lowers the number of customer calls and required

ruck rolls through proactive testing, and its advanced network segmentation and troubleshooting

apability.

A Yankee Group study demonstrated that advanced service offerings such as VoIP and IPTV gener-

te two to three times as many help desk calls as simple broadband services. Operator networks

sing IxRave for fault isolation showed significant improvements in problem resolution, preventing

xpensive “truck rolls” and pre-empting escalations.

Many sophisticated multiservice network faults are frustratingly transient in nature. IxRave periodi-

ally performs active tests on a specified service, identifying issues before they impact customers.

upport staff members avoid appearing unknowledgeable by using the established baseline whenustomers call.

urther, IxRave runs tests on other subscribers sharing the same infrastructure as a customer

xperiencing trouble. Since not every customer experiencing problems actually calls the help desk,

but instead takes their business elsewhere – potentially disparaging the service – it is important to

preempt issues before a customer knows there is a problem. IxRave probes subscribers in potential

rouble spots, supporting customers who are less likely to call a help desk.

An uncoordinated support staff requires the customer to repetitiously explain previous tests and

iagnostics, causing customer dissatisfaction. IxRave provides simple pass/fail criteria and sug-ested solutions to first level help desk personnel, and logs detailed technical statistics in the test

istory. If a help desk call is escalated, full technical details for all tests run on the customer’s

nfrastructure are available to higher level support staff. IxRave allows any personnel with access

o annotate tests with case-related, supplementary customer information.

Using IxRave for Ongoing Active Monitoring

uccessful network management comes from understanding basic network usage patterns. IxRave

utomatically runs tests on infrastructure elements, for any application mix, across an entire

etwork. IxRave generates periodic trend reports on the vital statistics of the network’s operation,which prevents service problems by allowing operators to detect trends.

xRave monitors network performance thresholds and alerts the management staff when the thresh-

lds are crossed, acting as a continuous sentinel of network health.

IxRave’s has a remarkably quick

return on investment (ROI)

that comes from a reduction of

unnecessary equipment swaps-- equipment that is often fully

functional.



Using IxRave for Service Level Agreements

IxRave’s test capabilities, coupled with detailed trend reports, make IxRave an ideal tool for ve

ing SLAs. This is especially useful to operators that provide VPN services.

A VPN allows an enterprise or company with many distributed sites to use of an operator’s infr

structure as if it were a network of private leased lines. Private data is only visible to the custom

and the network supports any private addressing and naming requirement particular to the

customer. Operators often provide VPN services using MPLS tunneling capabilities. An exampl

this type of network is shown in Figure 6.

Enterprises use SLAs as a guarantee of critical application network support that typically conce

ing bandwidth and throughput metrics. They require assurance concerning network latency, jit

and the resulting MOS if the enterprise uses the VPN for voice applications.

IxRave, if deployed with inexpensive test points that serve as SLA service demarcation points,

eliminates unneeded elements in the enterprise infrastructure from the service level calculation.

IxRave runs configured “mesh” tests to verify the VPN provides the required connectivity and p

formance characteristics. It generates reports summarizing the operator’s compliance with the

and triggers various types should network performance fall below set thresholds.

Customer Site 1

MPLS Core

Other Carriers/Internet

Customer Site 2

ServicePlatforms

(VioP, Video Applications

etc...)

Figure 6. IxRave Provides demarcation points for verifying SLAs in VPNs



ConclusionsCompetitive forces in the telecommunications market predict the inevitability of IP-based multiplay

ervices offerings. Multiplay services have shown good results in early deployments. IP provides

raditional voice and televisions services to mass market consumers, and it sets the stage for new

nd exciting converged services. It can potentially offer all such services with a significantly lower

ost structures.

Network operators offering multiplay services must ensure that IP-based services live up to cus-

omer’s quality expectations – a job made difficult by the subjective factors included in the defini-

on of QoE. Many parameters in the video compression algorithms that transport video signals

ver IP networks influence how well the signal performs over a given network, over which network

perators have little control. However, the ITU’s established minimum transport requirement metrics

or different types of video streams go a long way towards establishing the network characteristics

eeded for quality services.

ven current networks built with new high bandwidth services, and using equipment implementing

he latest QoS mechanisms, face many challenges. Such issues as the basic characteristics of IP

etworks, a high degree of change and large peak to mean traffic ratio suggest ongoing vigilance

s an absolute pre-requisite to successful commercial services.

xRave is a service verification offering from Ixia, the world’s leader in network test equipment.

xia developed the patented IxRave methodology in conjunction with leading operators, providing

simple methodology for testing the customer path.

xRave verifies network infrastructure and capacity using established QoE and QoS metrics, set byTU standards. It tests the entire network, end-to-end. This helps you “see what the customer sees.”

xRave achieves quick ROI by lowering incoming support calls and resulting truck rolls, while at

he same time increasing customer satisfaction -- results proven in actual network deployments.

xRave lowers deployment costs by testing network infrastructure and subscriber experience from

centralized test head that doesn’t rely on extensive deployments of expensive, hard to manage

probes. IxRave diagnoses and prevents issues by using both active and pro-active service testing,

ften before the customer is aware issues exit. If problems occur, IxRave gives the network opera-

or the necessary tools to fix them.

xia is pleased to discuss how IxRave can provide service assurance for your particular service

nvironment.

IxRave is a service verification

offering from Ixia, the world’s

leader in network test equipmen

Ixia developed the patentedIxRave methodology in conjunctio

with leading operators, providing

a simple methodology for testing

the customer path.



Ixia WorldwideHeadquarters

26601 Agoura Rd.Calabasas, CA 91302

(Toll Free North America)1.877.367.4942

(Outside North America)+1.818.871.1800

(Fax) 818.871.1805www.ixiacom.com

Other Ixia Contacts

Info: [email protected]: [email protected]

Public Relations: [email protected]: [email protected]

Sales: [email protected]: [email protected]: [email protected]

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