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Table of Contents

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Broadband Network Applications. . . . . . . . . . . . . 6

The Metro Area Network Infrastructure. . . . . . . 1 1

Elements of a 10GbE Solution. . . . . . . . . . . . . . 1 7

Differences Between 1GbE and 10GbE . . . . . . . 2 3

Elements of DWDM for the MAN . . . . . . . . . . 2 3Building 10GbE/ DWDM Metro Networks. . . . . 2 5

The Advantages of 10 Gigabit

Ethernet over DWDM . . . . . . . . . . . . . . . . . . . 2 8

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2

Glossary of Terms. . . . . . . . . . . . . . . . . . . . . . . . 3 3

A bout t he E d i t o r

Jerry Ryan is a principal at ATG and the Editor-in-Chief of

techguide.com.He is the author of numerous technology papers on var-ious aspects of networking. Mr.Ryan has developed and taught manycourses in network analysis and design for carriers, government agencies,and private industry. He has provided consulting support in the area ofWAN and LAN network design, negotiation with carriers for contractpricing and services, technology acquisition, customized software devel-opment for network administration, billing and auditing of telecommu-nication expenses, project management, and RFP generation. Mr.Ryanhas been a member of the Networld+Interop Program Committee andthe ComNet Steering Committee. He holds a B.S. degree in electricalengineering.

The Guide format and main text of this Guide are the property of The AppliedTechnologies Group, Inc. and is made available upon these terms and conditions.The Applied Technologies Group reserves all rights herein. Reproduction inwhole or in part of the main text is only permitted with the written consent of

The Applied Technologies Group. The main text shall be treated at all times as aproprietary document for internal use only. The main text may not be duplicatedin any way, except in the form of brief excerpts or quotations for the purpose ofreview. In addition, the information contained herein may not be duplicated inother books, databases or any other medium.Making copies of this Guide, or anyportion for any purpose other than your own, is a violation of United StatesCopyright Laws.The information contained in this Guide is believed to be reliablebut cannot be guaranteed to be complete or correct.Any case studies or glossariescontained in this Guide or any Guide are excluded from this copyright.

Copyright 2000,The Applied Technologies Group, Inc., 209 West CentralStreet, Suite 301, Natick, MA 01760, Tel: (508) 651-1155, Fax:(508) 651-1171E-mail: [email protected] Web Site:http:// www.techguide.com


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I n t roduc t ion

Network service providers face a variety of chal-lenges as they seek to capitalize on the opportunitiesresulting from emerging technologies, from advances innetwork standards and from ever more demandinguser requirements.Telecommunications industry de-

regulation has resulted in increased competition, hascertainly stimulated innovation and has helped toreduce service prices. At the Metro Area Network(MAN) level, there is now tremendous pressure forexpanded capacity to support broadband local accessand high-speed wide area networks, especially theInternet. All of these factors suggest that a flexible,proven MAN architecture combined with multi-vendorcompatible implementations is urgently needed so thatnew provider services can be introduced. Standards-based 10 Gb/ s Ethernet (10GbE), especially combined

with metro area optical fiber networks based on WaveDivision Multiplexing (WDM),promises to be a viablesolution it offers a hierarchy of speeds, end-to-endprotocol consistency, and technical features that areneeded by both providers and users.

Fundamentally, the push to develop 10GbE isbeing driven by the desire to interconnect EthernetLANs that may now be operating at 10,100 or 1,000Megabits/second. New types of applications forEthernet include application and content hosting,Internet-based data centers, server co-location and

others that go beyond the traditional enterprise. ThisTechnology Guide first examines these new applicationand infrastructure requirements to see why 10GbE hasbecome an attractive option for LAN and WAN packettransport. Next, the potential for 10GbE deploymentin both the MAN and the WAN is investigated.

Technology Guide 5

Bui ld ing 10 Gigabi t /DWDMM e t r o A r e a N e t w o r k s

The need to expand metropolitan network capacity to accom-

modate high-speed wide area networks is well recognized but

finding innovative, cost-effective solutions has not been easy.

Many metropolitan network service providers have been deploying

SONET and Wave Division Multiplexing across existing fiber

despite the difficulties in supporting existing customer networks,

particularly Ethernet. A new solution is emerging - 10 Gb/ s

Ethernet over DWDM fiber - that offers the advantages of speed,

flexibil ity, scalability, and technical simplicity. Extensions to

existing Ethernet standards have proven to be both feasible to

develop and practical to implement. T he 10 Gb/ s Ethernet stan-

dard, currently being developed by the IEEE with the assistance

of the 10GEA Committee, will be completed in early 2002 and

then used for open systems deployment. In the meantime, propri -

etary pre-standard products can provide interim support for

Ethernet networks in campus and metro environments. Interfaces

are being provided for a variety of transmission media, including

both single mode and WDM fiber. As companies move to begin

supplying 10 Gb/ s Ethernet products, certain questions sti ll

remain. For example, how will 10 Gb/ s Ethernet compare to the

existing versions of Ethernet? What functions, features and frame

structure will apply? What services can be expected from service

providers? This Technology Guide examines the driving forces for

10 Gb/ s Ethernet standardization, looks at the specific opportu-

nities for metropolitan network service providers, and shows how

10 Gb/ s Ethernet can fi t into a broadband network infrastruc-

ture. The ongoing efforts in the standardization of 10 Gb/ s

Ethernet will be highlighted.

4 Building 10 Gigabit/ DWDM Metro Area Networks


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standards and common practices have to beimplemented on a global scale.All the functionalityand capability that will be needed for the next genera-tion of applications must also be included in thesestandards.Much greater control over resources must beallowed, providers must be able to guarantee perfor-mance, and scalability must be improved by at least anorder of magnitude.

The re-emergence of Metropolitan Area Networksis being stimulated by the growth in e-commerce andthe outsourcing of key enterprise services such asextranets, back-office automation, telecommuting,content/ web hosting,and application services. In theearly days of the Internet, a simple, low-bandwidthlink offering a best effort class of service was readilyavailable and easily used but these low speeds are nolonger sufficient. Advanced applications include videostreaming, voice telephony, and on-line music distribu-tion, all depend on continuous access to a broadband

network infrastructure. These applications can nolonger be regarded as bleeding edge. Today's busi-ness-critical applications depend on the network beingavailable at all times, especially with transaction-basedsystems such as online purchasing, application hostingand soft product distribution. Applications that resideon a provider's host or are co-located with a networkbackbone provider also depend on high-quality, intelli-gent networks. 10GbE solutions appear to be widelyapplicable to these types of challenges while alsoremaining highly familiar to users and well-proven in

the marketplace.Examples of these new classes of application are

listed in Table 1.

Technology Guide 7

Standards for 10GbE are being developed by theIEEE (the 802.3ae committee) and will be promoted inthe marketplace by the 10 Gigabit Ethernet Alliance(10GEA). Completion of the formal standardizationprocess is expected by early 2002, with conformingproducts and deployments arriving shortly thereafter.In the meantime, pre-standard products are becomingavailable to support existing Ethernet networks in a

campus or metro environment. This Technology Guideexamines the progress of standards development andcompares 10GbE to earlier Ethernet standards. It alsodiscusses the advantages of using DWDM to providephysical connectivity for Ethernet.

Ethernet as an end-to-end network solution is anew concept, one that may come as a surprise to manynetwork architects and designers.Ethernet, originallyconceived only for use in local networks, is graduallybeing accepted at the MAN and WAN levels.ThisTechnology Guide reviews the benefits of having

Ethernet compatibility across local and metro networksand indeed from end-to-end.

Br o ad b a n d N e t w o r kAppl icat ions

The rapid growth rate of the Internet has gener-ated a considerable amount of publicity and is perhaps

subject to just as much debate. Expectations amongusers,providers and the general public are currently atan all time high in short, the Internet has alreadychanged and is expected to continue to change the faceof telecommunications. Its shear size and its growingimportance to business means that consistent technical



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The common threads among these applications are:

A demand for higher bandwidth:Metro area bandwidth

requirements have expanded rapidly as a result ofapplication outsourcing,campus/ building connec-tions and the general growth in Internet traffic.New co-location services require high speedcommunications for data centers,applicationhosting, etc.The new last mile solutions (xDSL,wireless broadband, etc.) are also forcing metronetwork providers to upgrade network capacity tokeep up with their customers.

Provision of feature-rich services:Although havinglarger pipes is fundamental, the real key to

competitive success is to create value-addedservices. Rapid service provisioning, priorityservices, and integrated management are exam-ples of facilities that need to be built into an intel-ligent network.Service features should also betransparent and consistent across the LAN, MAN,and WAN environments. End-to-end managementof these services (and the service features) is

Application Area General Requirements

Telecommuting/SOHO A home office network should be capable of

operating at the same speeds as the office

LAN and provide a transparent connection

between the two LANs. Provision of metro

or regional Ethernet connectivity supports

an office LAN that extends to the home with

virtually no degradation in service.High speed data Various applications are emerging that

transport would only be acceptable when large

amounts of data can be transferred while a

person waits (i.e., almost in real-time).

Software downloading and music distribu-

tion are just two examples of these new

applications.

Technology Guide 9

Table 1: Emerging 10GbE Applications

Application Area General Requirements

High speed Internet The aggregate Internet bandwidth

access requirements increase as the number of

Internet users grows. The amount of time

each user spends on the Internet is also

increasing due to new applications that are

being deployed. Newer applications typi-

cally also require more bandwidth and, inmany cases, higher quality of service.

Corporate LAN LANs must be interconnected for

interconnection distributed communications, for remote

servers and for home office access. Since

Ethernet dominates the LAN environment,

seamless connectivity among geographi-

cally distributed Ethernet segments is highly

desirable.

Back-end server Servers that were once distributed to

connections the department level have now been consol-

idated into more central server "farms" that

have to support high transaction rates.

Server networks need high bandwidths tominimize congestion and delay.

Inter- and intra-POP The service provider's Point of Presence

connections interconnects the Local Access and Core

Metro layers and may also include access

to the server farms. The POP itself could

include multiple networked switches to

enhance scalability and reliability and to

minimize congestion.

Real-time streaming Real-time data transfer places demands on

the network that can often be offset by

using higher capacities. Internet radio, voice

over IP and video on demand are real-time

communications applications. For example,

video data streams are by nature high band-

width and jitter sensitive. This type of data

transport, either broadcast or on-demand, is

only practical when a broadband infrastruc-

ture is available. Metro networks, which

provide the bridge between high speed

WANs and LANs, must not become a perfor-

mance bottleneck.



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Ethernet began its life as a high-speed alternativeto star-wired copper in premises networks, with itsfocus being on serving local applications. Over timeEthernet has been transformed into a genericnetworking technology for local, campus, metropolitan,and most recently for wide area networks. It hasproven to be scalable (from 10Mb/ s to 10Gb/ s andlikely beyond), flexible (multiple media, full/ half

duplex,shared and switched modes), easy to install andgenerally quite robust. Deployment of full-duplexGigabit Ethernet over dark fiber using long reachoptics has eliminated the distance barriers previouslyassociated with Ethernet technology. Use of Etherneton an end-to-end basis is very attractive to bothenterprise users and co-location providers because ofits simplicity, its familiarity and its relatively low cost.The emergence of 10GbE creates new options for datatransport over optical fiber and extends the value andlife of Ethernet technology.

The Met ro Area Ne tworkIn f ras t ruc ture

Metropolitan networks are undergoing a radicaltransformation. Developments in last mile and fiberoptic technologies, combined with the demands of thenew applications described in the previous section,

have put pressure on service providers and infrastruc-ture vendors to improve their services. Figure 1 illus-trates the basic elements of a metro network solutionand its relationship to access and long distancenetworks.

Technology Guide 1 1

important, especially if system management isoutsourced.

Integration and convergence:The mix and characteris-tics of the traffic on the network is changing as aresult of convergence. Applications such as IP-based telephony and streaming video are gainingacceptance and are being combined with conven-tional data transfer. Converged networks generallydepend heavily on the ability to manage andcontrol the quality of the network service.Convergence solutions increase the trafficengineering requirements for both the LAN andthe MAN.

Accessibil ity/ connectivity:Traffic patterns havechanged from LAN-centric (where the server andthe clients are typically on the same LANsegment) to MAN- or WAN-centric. The emer-gence of application service providers, for

example,means that all the traffic must flow to anexternal hosting location. Connectivity is nolonger primarily focused on a local workgroup itnow includes a much greater emphasis on regionalnetworks.

Quality and reliability:Network quality and reliabilityhave become important issues for both users andproviders. Reliability can be defined both for thenetwork elements (which can fail) and for thenetwork services (which can degrade or evenbecome unavailable).Most systems both in the

enterprise and at the application service provider now depend on having a network that operateswithin specified performance limits on a 24hour/ day, 7 day/week basis.Outages, packetlosses, and degraded services become increasinglydisruptive as the transmission speeds increase.

1 0 Building 10 Gigabit/ DWDM Metro Area Networks


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public network, and server access networks. A localaccess network includes all the network elementsbetween the provider's POP and the customer'send system. The two major access network compo-nents are: customer-owned LANs (with building,riser and campus levels), and the MAN access link(which is usually provider-owned).

Ethernet is the dominant technology for the LANat both the floor and backbone levels, often using amix of the older shared media and newer switchedmedia networks. Networks have traditionally been10 Mb/ s to the desktop (i.e., basic Ethernet), with100Mb/ s to the desktop now becoming the stan-dard, and with 100Mb/ s or 1Gb/ s being used forhigh performance users and external access.

The MAN access link is the infamous last milebetween the MAN or WAN provider and thecustomer premises. The demarcation point (the

point of responsibility hand-off from the networkprovider to the customer) can be located at thecustomer premises interface or at the provider'sPOP. The access link is often based on copper wiretechnologies, such as time division multiplexing,and has been relatively low in speed (especiallywhen compared to Gigabit Ethernet).Aggressivefiber deployment in major metro areas andadvances in last mile access technologies, such aswireless broadband and free space optics, removethis as a bottleneck and permit Ethernet to be used

as the link protocol.

b) Metro Core Networks

The metro core network must interface to both thelocal access network and the WAN access network.Historically, metropolitan area connectivity hasbeen provided by SONET rings which weredesigned and built to carry voice traffic. However,


Figure 1: LAN-MAN-WAN Networks

Three different levels exist in any enterprisenetwork infrastructure:

a) Access Networks

There are three classes of access networks: localaccess networks between a Point of Presence(POP) and the customer premises network, remoteaccess networks for off-site communications using a

WAN Access

Metro AreaOptical Network

LocalAccessNetwork

RemoteAccessNetwork

Server

AccessNetwork

Wide Area

Network



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require intelligent caching, load distribution, andsecure service partitioning without loss of perfor-mance. At the same time, access networkproviders require dynamic self-provisioning (i.e.,adding a new customer should not require revisingthe physical plant) to reduce operating costs andto maintain customer satisfaction. The metroinfrastructure must provide security to protect

customer data, reliability to route around failures,and scalability to maintain ROI throughout hecticsubscriber acquisition and growth cycles.

Bandwidth control and service provisioning:Serviceproviders that make optimal use of their resourcesare more profitable. Bandwidth control and rapidservice provisioning are among the importantfunctions that network equipment must nowperform, providing one of many opportunities forcharging on the basis of service levels. Managingdata flows, multiplexing lower speed data streams,and limiting network accessibility are examples offunctions that manage the consumption ofnetwork bandwidth. Delivering services to thecustomer on short notice can be very important,especially when the service is viewed as competi-tive and a commodity. The ability to set up andtear down the network links and to provisionoptical bandwidth in bit-level increments, withminimal time and effort involved, reduces costsand retains customer loyalty. Intelligent bandwidthprovisioning and advanced traffic engineering is

the launch point for differentiated services forcustomers. It also allows service providers to scaleand auto-provision their optical bandwidthaccording to business metrics, thus creating profitsby capturing revenue that would otherwise be lost.

Traffic engineering:As optical networks begin todeliver almost unlimited bandwidth to end users,service providers need to deliver differentiated


most of the traffic growth in these networks is nowdue to data applications. Data traffic volume hasalready surpassed voice traffic volume in manymetropolitan areas. The SONET transport infra-structure is not optimized for data traffic andcannot scale to support the rapid growth of theInternet in a cost effective manner.

Metro service providers are looking for cost effi-cient, data-optimized solutions to replace existingSONET infrastructures. Metropolitan networksand their providers need to evolve to meet thefuture application needs and to remain competi-tive. Provision of value-added services as an inte-gral part of the provider's infrastructure is one ofthe steps that needs to be taken.

c) Wide Area NetworksWANs have always been an essential ingredient inany large enterprises network infrastructure.Various technologies have been used for low andhigh speed WAN transport including time divisionmultiplexing,circuit switching, and packetswitching. Ethernet has only recently become apossible solution at this level.

Metropolitan networks serve largely as amiddleman for other networks, as is suggested inFigure 1. This involves considerably more thanproviding a simple high speed connectivity service,however. In fact, it is the value-added services andfeatures that serve to differentiate one metropolitannetwork provider from another.A service-richplat-form should include the following features:

Leverage the existing infrastructure:Service providersmust offer advanced capabilities to support theservices delivered over the metro network.Content and application hosting, for example,



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migrate to IP, interoperability between IP andother communications technologies will become alarger concern for service providers. Supportshould be available for all copper,cable, and fibermedia types to ensure that services can be quicklydelivered to any customer in any environment.Any of the major infrastructure types, includingATM, Packet over SONET, DWDM, Gigabit

Ethernet, T1 or T3,and coaxial cable should alsobe supported.Metro network evolution must beachieved in a way that guarantees interoperabilitywith the vast base of already installed local andwide area networks (legacy networks).

In short, bandwidth control and accounting notjust simple bandwidth availability lie at the heart ofthe new business-oriented Internet and managednetwork services; without these capabilities, profitableservice delivery for the metro area is impossible.

Elements of a 10GbE Solut ion

The overall goals of the IEEE standards effort is toextend the existing IEEE802.3 standards to support10Gb/ s speeds and to enhance Ethernet to includesupport for WAN links. Standards for 10GbE will beproduced as an extension to the existing IEEEstandards with the basic changes being at the Physical

Layer.The physical media to be supported by 10GbEproducts are currently being specified, with the firstdraft of the proposed standard due to be available inthe fall of 2000.

Ethernet was first developed over twenty years agoto provide a solution for high speed data communica-tions within a building. The first IEEE and the ISOstandards were for use with a bus-oriented coaxial


services dynamically. Various functions can beapplied to the incoming traffic and to traffic flowsin order to improve its overall networkperformance. Service classes for example, can bebased on the identity of the customer or the typeof application. Service providers can use trafficengineering either to offer different service levelsor to ensure service quality for time-critical traffic

such as voice or video.Through the use of routing(BGP, IS-IS,OSPF),multi-protocol label switching(MPLS),virtual private networks (VPNs) anddifferentiated services (DiffServ), the next genera-tion of switch-routers should be able to set priori-ties and offer advanced traffic engineering andhardware-based rate limiting throughout thenetwork.

Real-time accounting:The transition from sellingcommodity optical bandwidth to selling serviceswill require that carriers and service providersbuild an infrastructure that allows them to handle-and profit from business traffic. They must be ableto monitor bandwidth usage to ensure thatcustomers are getting what they were allocatedand have paid for, and then be able to reliablyaccount and bill for these allocations in real-time.Service providers also need the intelligence toidentify customers who consistently bump upagainst their limits because therein lies an oppor-tunity to sell additional services. By providing anopen application-programming interface (API),

integration with billing and provisioning systems,and existing operations support systems (OSS) canbe achieved more easily. This intelligence enablesservice providers to quickly provision and deliveradvanced services to their customers.

Compatibility:Older networks must also be accom-modated, with the goal being to avoid re-designinglocal networks. As more and more networks



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Broad market potential:Any network technology thataims to be strategic and ubiquitous must be adapt-able to a wide range of applications and providedistinct benefits over competing solutions. SinceEthernet access links at 100Mb/ s and 1Gb/ s arenow being used, the core networks must be able toaggregate multiple access links. The number ofvendors that are committed to producing

standards-based 10GbE products indicates a defi-nite market appeal.

Distinct identity:The 10GbE standard should be aunique solution, thereby avoiding mutually incom-patible competing solutions. Ideally, the standardwould be a simple extension to the existingIEEE802.3 standards without any need for uniquefeatures. Related standards,such as the MIB,should also be straightforward extensions of thecurrent lower speed standards.

Economic feasibil ity:The costs associated withproducing the new products, implementing thesolutions and maintaining the implementednetworks should be reasonable when compared toother versions of Ethernet and competitive tech-nologies. Costs should be reasonable for theperformance expected.

Figure 2 illustrates the functional elements that aredefined by the Ethernet standards. There are two func-tional layers (as per the OSI model): the Physical Layer

(PHY), and the Data Link Layer. In order for 10GbEto look like traditional Ethernet to its users, the MACuser interface must be the same.


cable,offering a shared half-duplex service at a speedof 10Mb/s. This initial standard has evolved consider-ably: copper, fiber optic, and wireless media have beenadded; switched,star-wired operations have largelyreplaced shared media; full-duplex operation has beenadded; and speeds have increased to 100Mb/ s andmore recently to 1Gb/ s. Other standards have beendeveloped for a Management Information Base (MIB)

for network management, for supporting virtual LANsand for quality of service extensions. Since Ethernetoperations and performance characteristics have beenstudied extensively, considerable experience is nowavailable among the manufacturers, the networkproviders, and enterprise customers.

The following were among the criteria used by theIEEE committee to determine the suitability of stan-dardizing 10GbE:

Technical feasibility:The 10GbE standard had to be

technically feasible and implementable usingexisting proven technology. Working models of theimplemented standard should be available prior toits finalization. Reliability should be at least equalto earlier Ethernet standards.

Standards conformance:Ethernet networks thatoperate at different speeds need to be compatible(i.e., 10GbE has to be Ethernet in more than inname only) in order for scalability to be preserved.Most of the benefits of end-to-end Ethernetwould be lost if gateways between segments were

necessary.



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Table 2 lists the distance specifications that are thecurrent targets for 10GbE implementations.

Table 2: Distance Targets for 10GbE

Source:Tables in this section are based on work in progress in theIEEE which is summarized at www.10gigabit-ethernet.com.

a) LAN/ MAN Media

A number of alternative media types are beingconsidered for LAN/ MAN environments. Since10GbE is not expected to connect directly to userend-systems (at least not yet) the standards areinitially being restricted to optical fiber.Optionsbeing considered for the optical layer include

Multi-mode fiber (MMF) and Single-mode fiber(SMF) using serial and parallel links.

b) WAN MediaThe concept of Ethernet-based communicationsover long distances is unique to 10GbE and wouldnot be feasible using the original CSMA/ CDprotocol (i.e., shared media with contention). Therestriction to full-duplex operation allows 10GbEto operate over long link spans, repeaters andother transport layers like DWDM or SONET.

10GbE WAN physical layer is also defined to becompatible with SONET. It can be said that10GbE will be SONET friendlyeven though itis not fully compliant to all of the SONET stan-dards. Some SONET features are still to be imple-mented: the OC-192 link speed, the use ofSONET framing, and some over head processing.Others, the most costly aspects of SONET, will be

Type of Fiber Targeted Distances (m)

Existing installed multi-mode fiber 100m

Multi-mode fiber 300m

Single-mode fiber 2km, 10km, 40km


Figure 2: Ethernet Functional Components

Opt ica l Med ia /Physica l M ed ia Dependent (PMD)Sublayer

Increases in the speed of Ethernet have beenmade possible largely by advances in fiber optics andsignal processing technologies. Since transmission

capacity and segment distance are strongly influencedby the characteristics of the media being used, eachnew generation of Ethernet involves the developmentof new Physical Layer standards.

Two families of PHY (consisting of the PCS,PMA, and PMD sublayers) are currently under devel-opment:a LAN PHY operating at 10Gb/s, and aWAN PHY operating at a data rate compatible withthe payload rate of OC-192c and SDH VC-4-64c.

MAC Control

Media Access Control (MAC)

Reconciliation

Physical Coding Sublayer (PCS)

10G Media Independent Interface (XGMII)

Physical MediaAttachment (PMA)

Physical Media Dependent (PMD)

Media Dependent Interface (MDI)

Media (Optical Fiber)



13/27

Dif ferences Between 1GbE and1 0 G b E

Table 3 provides a brief comparison between the1Gb/ s and 10Gb/s versions of Ethernet. There areseveral important restrictions that apply to 10GbE: thetraditional CSMA/ CD protocol will not be used,andcopper wiring will not be an option (at least not for endstation links).

Table 3: Comparison of 1GbE to 10GbE

Elements o f DWDM for theM AN

The Internet has been transformed into a web ofinterconnected MANs, with inexpensive optical fiberbeing the underpinnings for the new MAN infrastruc-ture.Technical advances in infrastructure equipmentare breaking the bandwidth bottleneck.This transfor-

Characteristic 1 Gigabit 10 GigabitEthernet (1GbE) Ethernet (10GbE)

Physical media Optical and copper Optical media onlymedia

Distance LANs up to 5km. LANs to 40km.Direct attachment toSONET/SDH equipmentfor WANs

PMD Leverages Fiber Creates new opticalChannel PMD's PMD's

PCS Re-uses 8B/10B Establishes new codingcoding schemes

MAC protocol Half-duplex Full-Duplex only(CSMA/CD) +Full-Duplex

Additions Carrier extension Throttle MAC speedfor Half-duplex

Derived from:A Brief Introduction to 802.3ae available at www.10GEA.org


avoided:TDM support, performancerequirements,and management requirements.SONET, which was designed primarily for voiceapplications, supports point-to-point linksoperating at a well-defined hierarchy of speeds(i.e., OC-1 at 51.840 Mb/s up to OC-192 at9,953.281Mb/s).

Physical Media At tachment (PMA) Sublayer

The PMA provides for the serialization and de-serialization of the data being transmitted. It is respon-sible for supporting multiple encoding schemes sinceeach PMD will use an encoding that is suited to thespecific media it supports.

Physical Coding Sublayer (PCS)

The PCS sublayer provides for packet delineationand scrambling for the LAN PHY. Various proposalsare under consideration (8B/10B encoding was usedfor Gigabit Ethernet and was adopted from the ANSIstandard Fiber Channel).

Media Access Control (MAC) Sublayer

The MAC sublayer, the highest layer defined inthe Ethernet standards, must conform to the existingstandards in order to maintain compatibility across allspeeds. The scope of the IEEE802.3 standards work isto define MAC parameters and, if necessary, a

minimal augmentation of MAC operation for the fullduplex transfer of LLC and Ethernet format frames at10Gb/s.

Several proposals have been made to incorporatepacing into the operation of the MAC sublayer. This isneeded to accommodate the mismatch between MACspeed and the line transmission rate. There is, as yet, nofinal decision on how this function will be standardized.



14/27

An optical multiplexer combines the opticalsignals for transmission over the fiber strand;

Optical amplifiers are used to pump up the opticalsignal power and to compensate for system losses;

An optical demultiplexer separates the receivedsignal into its components for delivery to receiversthat then convert the signal back to electrical

form;Optical signals can be added and removed from a

system using Optical Add Drop Multiplexers(OADMs) which groom and split the opticalsignals along the transmission path.

Currently, WDM systems are required to convertto and from electrical signals, perform cross-connec-tions and to do switching. The next generation ofWDM optical transport networks will eliminatethis step by supporting optical switching. An optical

transport network will support lightpaths at up toseveral gigabits per second that can be established andreleased using a dynamic management system (ratherthan through static configurations).

Since DWDM solutions are not bound by thebandwidth hierarchy defined for SONET (e.g., OC-48at 2488.32Mb/s or OC-192 at 9953.28Mb/s), theycan be adapted for use directly with Ethernet.

Bui ld ing 10GbE/DWDM Met roN e t w o r k s

A question that many metro network providers willsoon need to answer is how to incorporate 10GbE intotheir network infrastructure. As the number of100Mb/s Ethernet links at the edge of their networks


mation is being driven by two areas of technologicalinnovation:

High-speed access technologies have eliminatedthe local loop, last-mile bottleneck. In the localloop, broadband access including Ethernet,wavelength division multiplexing (WDM),cable,digital subscriber line (DSL),and wireless isbringing high-speed connectivity to small andmedium-sized businesses.

The introduction of DWDM allows orders ofmagnitude increases in bandwidth on a givenstrand of fiber. In the carrier backbone, and anever-increasing part of the Metro core, DWDMswitches are replacing traditional SONETswitches. This creates a plentiful supply of cost-effective bandwidth in the metropolitan core.Combining basic transmission capacity with rapidservice provisioning and dynamic wavelength

management greatly reduces the cost and deploy-ment time for a MAN infrastructure.

Wave Division Multiplexing is a technology thatenables multiple optical signals to be transmitted by asingle fiber using the 1300 or 1500nm wavelengthwindows. Initially, each window was used to transmit asingle digital signal (this was called WDM).An increase toallow 4 channels has been called Wide WDM (WWDM).With current technologies, over 100 optical channels canbe multiplexed onto a single fiber,this is referred to as

Dense WDM,or DWDM.Adding new terminatingequipment to increase the number of channels is muchless expensive than physically laying new fiber.

The key elements of a WDM link are:

Lasers are used as transmitters, one for each wave-length. DWDM systems can be pre-built withlasers that can be turned on or off whenever thewavelength is allocated to a user;



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the anticipated demand. Network managementsystems can be integrated across the differentnetwork speeds and configurations.

IP directly over SONET is expensive and difficult tomanage when the number of links becomes large.Ethernet over SONET, on the other hand,adds aswitching capability that can reduce the number ofpoint-to-point links (i.e., a full mesh may not berequired). Ethernet allows LAN, MAN, and WANnetworks to be combined to form end-to-endconnections, thereby reducing the need for formatand protocol conversions within the network.

b) Packet over Ethernet over WDM-based

Optical (PEW)

A variation on the above is to transport Ethernetover a WDM-based physical layer,with or withouta thin SONET interface. A small subset of theSONET header and SONET scrambling is usedbut the majority of the overhead is eliminated.This solution avoids the complexities of SONETTDM functions, the stringent SONET physicallayer specifications,and the need for a separateSONET element management system.

A key advantage of PEW is that the overheads ofATM and SONET can be eliminated.Both 1GbEand 10GbE are more affordable, practical, andsimpler than ATM, the major alternative for highspeed WANs.

c) Packet over Ethernet over Fiber (PEF)In the metro area,enterprise customers can use10GbE over dark fiber to support requirementssuch as serverless buildings, remote hosting, off-sitestorage or backup, and disaster recovery. Metroservice providers can build 10GbE backbones withless complex and costly POPs.


increases, so will the need for 10GbE to aggregate1Gb/ s links in data centers and in the backbone.10GbE has a role to play in metro and regionalnetworks, but how the architecture and configurationswill develop is less clear at this stage.

Alternatives for building a full-function Ethernet-based metro network to support IP transport are illus-trated in Figure 3 (existing technologies such as FDDI,

ATM, and SONET are not included here).

Figure 3: Metro Network Architectures

a) Packet over Ethernet over SONET-based

Optical (PES)

IP packets can be transported directly over a fullSONET infrastructure using PPP encapsulation orover an Ethernet segment built from SONETlinks. SONET would be preferred for longdistances and could be also be used at the MAN

level. Full SONET TDM capabilities, the SONETphysical layer,and the various SONET manage-ment functions would all be included, resulting inconsiderable overhead.

PES is based on proven technologies that arewidely installed and well understood. Ethernet isscalable from 10Mb/s up to 10Gb/ s, allowing thebandwidth offered to be more closely matched to

IP

10GbE

Dark Fiber

(c)

IP

10GbE

DWDM/Fiber

(b)

IP

10GbE

DWDM/Fiber

(a)

[Thin SONET]

SONET



16/27

are comfortable with Ethernet. Its use by serviceproviders within their own environments, however, isrelatively new and has yet to be tested on a wide scale.

Ethernet implementations are generally standardand are interoperable and interchangeable. A largenumber of suppliers offer Ethernet components, whichhas driven the prices down and encourages continuedinnovation. It has been claimed that Ethernet in the

wide area may cost as little as one-fifth the cost ofSONET and one-tenth the cost of ATM [www.nwfu-sion.com/archive/ 2000/ 84044_01_17-2000.html].

Ethernet is also viewed as being media agnosticsince it interfaces transparently with various transmis-sion media including cable, copper wire,and severaltypes of fiber.The ability to mix and match at themedia level avoids significant re-wiring costs that mightotherwise be necessary.

DWDM (and really any form of WDM) alsoprovides a number of advantages for metro network

environments. Clearly, the most important is its abilityto optimize existing fiber installations. WDM providesan alternative to SONET-based technologies, allowinga closer match of bandwidth supply to user demandswhile also making provisioning much more flexible anddynamic while also eliminating some of the legacybaggage of SONET technology.

Optical switched networks, which will also bebased on DWDM, are promising to bring new intelli-gent services to both enterprise-based and provider-based customers. Ethernet networks which are essen-

tially distance insensitive will reduce costs, simplifyoperations, and increase performance, all withoutmajor disruptions in existing applications.


The various parts of a metro network were illus-trated in Figure 1. 10GbE will be used for aggre-gating slower access links, will be used in the back-bone networks of the providers, and can alsoprovide WAN access. The choice of buildingblocks for a metro service provider, will dependon the existing network infrastructure, the need tointerconnect older network technologies and the

types of value-added services that are beingconsidered.

The Advantages of 10 GigabitE t h e r n e t o v e r D W D M

The advantages of a combined 10GbE/ DWDMsolution can be examined from three distinctly different

perspectives: the advantages of each technology byitself, the benefits of having Ethernet as a service, andthe operational/ managerial advantages of end-to-endconsistency. Each is important to consider when evalu-ating solutions to offer to customers.Given the rapidlyadvancing standards,metro service providers shouldnow be examining the payback of using 10GbE whenthe standard is completed or even sooner with pre-standard products.

Technology Advantages

Ethernet has proven to be a very adaptable, reli-able, uncomplicated technology. Ethernet is consideredto be a plug and playsolution requiring only aminimum of planning, design, and testing. Perhaps oneof the most important advantages is that thetechnology of Ethernet has had many years of usageand study. Both the service providers and the end users



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handle both the LAN and MAN facilities are anopportunity for the service provider.

Using Ethernet, new services can be deployedfaster. Since most customers already use Ethernet,there would be less training required.

Mar ket ing Advant ages

Although it may not seem important whencompared to the technical advantages, Ethernet can berelatively easily sold to most customers.Mostenterprises already have experience with Ethernet andwould be willing to accept its use by service providers,especially if outsourcing is a possible option. The useof Ethernet across the MAN and WAN also expandsits market penetration, increasing its popularity evenfurther.

Ethernet also provides a means to avoid re-engi-neering an existing network, all of which results in

happier customers.


Architectural Advantages

The major advantage of Ethernet is its emergingpotential to serve as a true end-to-end solution.Existing customer networks can be supported in nativemode, eliminating format conversions at the networkboundaries. This eliminates some of the networkprocessing that would be needed when different datalink protocols are used and, therefore, reducescomplexity.

Ethernet is a scalable solution. The IEEEstandards currently specify Ethernet at 10 Mb/s, 100Mb/s (Fast Ethernet), 1Gb/ s (Gigabit Ethernet) andthis will soon be extended to 10Gb/ s. Even higherspeeds are on the planning horizon and are expectedto be viable in the future. Thus, network designers canstart at much less than 10GbE and build up as capacitydemand expands.

One drawback to the use of Ethernet would bethe need to interface to other legacy networks such as

frame relay, ATM, and TDM access. However, thisform of conversion has become a routine function of arouter.

Management Advantages

Operations, administration, maintenance, andprovisioning (OAM&P) the basic tasks of manage-ment systems are also improved through the use ofEthernet across the MAN and WAN. Faster bottomline profit through lower costs for equipment and

support is, of course, one of the most importantadvantages.

Network management systems can be simplified ifthe same system can be used at all levels of thenetwork. Although most networks have one customer-controlled part and another provider-controlled part,the use of common facilities makes integrated manage-ment a practical alternative. Managed services that can



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Glossary of Terms

10 Gigabit Ethernet (10GbE) The emergingIEEE standard for Ethernet operation at 10 Gbps.

10 Gigabit Ethernet Alliance(10GEA) Anorganization promoting the rapid deployment of

10GbE.

10 Gigabit Media Independent Interface

(XGMII) The interface between the media depen-dent and media independent parts of the Ethernetprotocol stack.

Add/ Drop Multiplexer (ADM) A multiplexercapable of extracting or inserting lower-rate signalsfrom a higher-rate multiplexed signal withoutcompletely demultiplexing the signal.

American National Standards Institute (ANSI)The coordinating body for voluntary standardsgroups within the United States. ANSI is a member ofthe International Organization for Standardization(ISO).

Application Program Interface (API) Meansof communication between programs to give oneprogram transparent access to another.

Asynchronous Transfer Mode (ATM) A cell-

based, fast-packet technology that provides a protocolfor transmitting voice and data over high-speednetworks. ATM is a connection-oriented technologyused in both LAN and WAN environments. It is asyn-chronous in that the recurrence of cells depends onthe required or instantaneous bit rate.

Glossary 3 3

S u m m a r y

Ethernet has evolved from its shared LAN rootsinto one of the most important networking technolo-gies of our time. It dominates the LAN and thedesktop connection and has proven to be suitable forbuilding and campus backbones. Moreover,Ethernet is

scalable from 10 Mbps to 1Gbps today, with10Gbps being standardized now, and with even higherspeeds on the drawing boards. Ethernet over opticalfiber is now used for metro networks and is beingconsidered for wide area networking. Users andproviders both consider Ethernet to be a well-known,well-understood technology, with a high comfort levelamong technical experts and network operators.

High speed intelligent networks are becomingessential to success with newer applications such asreal-time telephony, the demand that is expected to

grow rapidly. Exploitation of a high-speed, service-richinfrastructure can provide a competitive edge. Theextension of Ethernet to 10Gbps ensures scalabilityacross a wide range of speeds while also promotingconsistency, interoperability and manageability.Building networks using Ethernet from end-to-endreduces overall technical complexity, simplifies thenetwork management system,and makes capacityexpansion more straightforward.

Optical fiber with DWDM supporting 10GbpsEthernet will be a powerful solution for metro back-

bone networks. Pre-standard products are becomingavailable now, with full ratification of the formal stan-dards expected to take place in March 2002. Serviceproviders should first understand the issues and oppor-tunities surrounding end-to-end Ethernet networks,and then should begin to incorporate 10G Ethernetinto their service development and deployment plans.



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Border Gateway Protocol (BGP) Protocol forcommunications between a router in one autonomoussystem and routers in another.

Carrier Sense Multiple Access/ Collision

Detection(CSMA/ CD) A channel access mech-anism wherein devices wishing to transmit first checkthe channel for a carrier. If no carrier is sensed for

some period of time, devices can transmit. If twodevices transmit simultaneously, a collision occurs andis detected by all colliding devices, which subsequentlydelays their retransmissions for some random length oftime. CSMA/ CD access is used by Ethernet andIEEE 802.3.

Data Link Layer Layer 2 of the OSI referencemodel. This layer takes a raw transmission facility andtransforms it into a channel that appears, to thenetwork layer, to be free of transmission errors. Itsmain services are addressing, error detection, and flowcontrol.

Differential Services IETF Standard

(DiffServ) A set of IETF standards designed toallow QoS support in IP networks by providing ameans to distinguish among classes of service.

Ethernet (1) A baseband LAN specificationinvented by Xerox Corporation and developed jointlyby Xerox, Intel, and Digital Equipment Corporation.Ethernet networks operate at 10 Mbps using

CSMA/ CD to run over coaxial cable. Ethernet issimilar to a series of standards produced by IEEEreferred to as IEEE 802.3. (2) A very common methodof networking computers in a local area network(LAN). Ethernet will handle about 10,000,000 bpsand can be used with almost any kind of computer.


Fast EthernetTerm given to IEEE 802.3u (calledFast Ethernet) for Ethernet operating at 100 Mbpsover Cat-3 or 5 UTP.

Fiber Distributed Data Interface (FDDI) Anemerging high-speed networking standard. Theunderlying medium is fiber optics, and the topology isa dual-attached, counter-rotating Token Ring. FDDI

networks can often be spotted by the orange fibercable. The FDDI protocol has also been adapted torun over traditional copper wires. An ANSI-definedstandard specifying a 100 Mbps token-passing networkusing fiber-optic cable. Uses a dual-ring architecture toprovide redundancy.

Fiber Optic Cable A transmission medium thatuses glass or plastic fibers, rather than copper wire, totransport data or voice signals. The signal is imposedon the fiber via pulses (modulation) of light from alaser or a light-emitting diode (LED).Because of itshigh bandwidth and lack of susceptibility to interfer-ence, fiber-optic cable is used in long-haul or noisyapplications.

Fiber Optics A method for the transmission ofinformation (sound, pictures, data). Light is modulatedand transmitted over high purity, hair-thin fibers ofglass. The bandwidth capacity of fiber optic cable ismuch greater than that of conventional cable orcopper wire.

Gigabit Ethernet A 1Gbps standard forEthernet.

Gigabit Ethernet Alliance An association ofGigabit Ethernet manufacturers and suppliers formedfor the purpose of promoting Gigabit EthernetTechnology.

Glossary 3 5


20/27

Media Access Control (MAC) IEEE specifica-tions for the lower half of the data link layer (layer 2)that defines topology dependent access control proto-cols for IEEE LAN specifications.

Media Access Control Sub Layer (MAC Sublayer) As defined by the IEEE, the lower portionof the OSI reference model data link layer. The MAC

sub layer is concerned with media access issues, suchas whether token passing or contention will be used.

Media Attachment Unit (MAU) In IEEE802.3, a device that performs IEEE 802.3 Layer 1functions, including collision detection and injection ofbits onto the network.

Media Independent Interface (MII)Thestandard in Ethernet devices to transparently intercon-nect the MAC sublayer and the PHY physical layer,regardless of media.

Media Interface Connector (MIC) FDDI defacto standard connector.

Megabit (Mb/ s) One million bits per second.

Megabits per Second (Mbps) A digital trans-mission speed of millions of bits per second.

Metropolitan Area Network (MAN) A datacommunication network covering the geographic areaof a city (generally, larger than a LAN but smaller

than a WAN).

Multimode Fiber Optical fiber with a corediameter of 62.5 or 50 microns. Dispersion of light isgreater than single mode fiber so distances are less.

Multimode Fiberoptic Cable (MMF)

Fiberoptic cable in which the signal of lightpropagates in multiple modes or paths. Since these

Glossary 3 7

Gigabits Per Second (Gbp/ s) Billion bits persecond. A measure of transmission speed.

IEEE 802.1p An IEEE draft standard thatextends the 802.1D Filtering Services concept toprovide both prioritized traffic capabilities and supportfor dynamic multicast group establishment.

IEEE 802.2 IEEE LAN protocol that specifies animplementation of the logical link control sub layer ofthe link layer. IEEE 802.2 handles errors, framing,flow control, and the Layer 3 service interface.

IEEE 802.3u IEEE LAN protocol that specifiesan implementation of the physical layer and MAC sublayer of the link layer. IEEE 802.3 uses CSMA/ CDaccess at a variety of speeds over a variety of physicalmedia.One physical variation of IEEE 802.3(10Base5) is very similar to Ethernet.

IEEE 802.5 IEEE LAN protocol that specifies animplementation of the physical layer and MAC sublayer of the link layer. IEEE 802.5 uses token passingaccess at 4 or 16 Mbps over shielded twisted pairwiring and is very similar to IBM Token Ring.

IEEE 802.6 Standards being developed by IEEEto govern metropolitan area networking.

Institute of Electrical and Electronic

Engineers (IEEE) Professional organization thatdefines network standards. IEEE LAN standards are

the predominant LAN standards today, includingprotocols similar or virtually equivalent to Ethernetand Token Ring.

Management Information Base (MIB) Adatabase of information on managed objects that canbe accessed via network management protocols suchas SNMP and CMIP.



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Optical Carrier 3 (OC-3) Optical Carrier level3, SONET rate of 155.52 Mbit/ s, matches STS-3.

Optical Carrier- N (OC-N) Higher SONETlevel, N times 51.84 Mbit/ s.

Physical Coding Sublayer (PCS) One of thesublayers defined for the Ethernet protocol stack.

Physical Layer (PHY) The bottom layer of theOSI and ATM protocol stack, which defines the inter-face between ATM traffic and the physical media.The PHY consists of two sublayers: the transmissionconvergence (TC) sublayer and the physical medium-dependent (PMD) sublayer.

Physical Medium Dependent (PMD) A sublayer of the physical layer that interfaces directly withthe physical medium and performs the most basic bittransmission functions of the network.

Points of Presence (POP) A term used byInternet service providers to indicate the number ofgeographical locations from which they provide accessto the Internet.

Protocol Data Unit (PDU) A discrete piece ofinformation like a frame or a packet in theappropriate format for encapsulation and segmenta-tion in the payload of a cell.

Quality of Service (QoS) Term for the set of

parameters and their values which determine theperformance of a given virtual circuit.

Shared Ethernet Conventional CSMA/ CDEthernet configuration to which all stations areattached by a hub and share 10 or 100 Mbps of band-width. Only one session can transmit at a time. This isthe most popular network type today

Glossary 3 9

paths may have varying lengths, a transmitted pulse oflight may be received at different times and smearedto the point that pulses may interfere with surroundingpulses. This may cause the signal to be difficult orimpossible to receive. This pulse dispersion sometimeslimits the distance over which a MMF link can operatesupporting propagation of multiple frequencies oflight.

Multiple Protocol Label Switching (MPLS)

A set of IETF standards that are designed to allowpacket flows to be switched on the basis of labelsinstead of the full destination addresses, therebypromoting higher performance and allowing trafficengineering.

Open Shortest Path First (OSPF) A routingprotocol used in IP networks.

Operation Support System (OSS) The

management subsystem for provider-based networks.

Operations Administration Maintenance and

Provisioning (OAM&P) Tasks performed by themanagement and administrative systems in a network,especially with reference to public networks.

Optical Add Drop Multiplexer (OADM) AnADM used with fiber optics (see ADM).

Optical Cable Level 3 (OC-3) Definedstandard for the optical equivalent of Synchronous

Transport Signal 3 (STS 3) transmission rate or STS3c Synchronous Optical Network Transport Systems(SONET) transmission rate. The signal rate for thesestandards is 155.52 Mbps.

Optical Carrier 1 (OC-1) ITU-ISS physicalstandard for optical fiber used in transmission systemsoperating at 51.84 Mbps.



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Wave Division Multiplexing (WDM) A tech-nology that allows multiple wavelengths to be multi-plexed over a single strand of fiber. Comes in variousforms including Dense and Wide depending on thenumber of wavelengths involved.

Glossary 4 1

Single-mode Fiber Also called monomode.Single-mode fiber has a narrow core that allows lightto enter only at a single angle. Such fiber has higherbandwidth than multimode fiber,but requires a lightsource with a narrow spectral width (for example, aLASER).

Synchronous Digital Hierarchy (SDH) ITU-

TSS international standard for transmission overoptical fiber.

Synchronous Optical Network (SONET) Aset of standards for transmitting digital informationover optical networks. Synchronous indicates that allpieces of the SONET signal can be tied to a singleclock. A CCITT standard for synchronous transmis-sion up to multigigabit speeds

Time Division Multiplexing (TMD) A formof transmission in which different flows are combined

on the basis of time slots.

Transparent Bridging Bridging schemepreferred by Ethernet and IEEE 802.3 networks inwhich bridges pass frames along one hop at a timebased on tables associating end nodes with bridgeports. Transparent bridging is so named because thepresence of bridges is transparent to network endnodes.

Transport Control Protocol/ Internet Protocol

(TCP/ IP) A protocol (set of rules) that providesreliable transmission of packet data over networks.

Wide Area Network (WAN) A network whichencompasses interconnectivity between devices over awide geographic area.Such networks would requirepublic rights-of-way and operate over long distances.



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Notes 4 3

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_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

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_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _


25/27

Notes 4 7

NOTES

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _


NOTES

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _


26/27

Total Contr o l fort he M et r o Net w or k

At home in the Metro Area Network, the peering center,

the hosting center, and the intelligent building, R iverstone's

RS family of switch routers delivers industry leading, high-perfor-mance connectivity, hardware-accelerated bandwidth control and

accountability, and massive scalability. The RS family supports all

media interfaces from 10 G igEthernet to T1/E1, T3/E3, P acket

over SONET, AT M and everything in between. And did we men-

tion that the RS platform supports ALL IP routing protocols?

Learn more about Ri verstone Networks and the industry's leading

family of switch routers. Visit our Website at riverstonenet.com

or for more information call 408-878-6500.


27/27

This Technology Guide is one in a series of topic-

focused Guides that provides a comprehensive

examination of important and emerging technologies.

This series of Guides offers objective information

and practical guidance on technologies related

to Communications & Networking, the Internet,

Computer Telephony, Document Management,Data Warehousing, Enterprise Solutions, Software

Applications, and Security.

Built upon the extensive experience and ongoing

research of our writers and editorial team, theseTechnology Guides assist IT professionals in making

informed decisions about all aspects of technology

development and strategic deployment.

techguide.com is supported by a consortium of lead-ing technology providers. Riverstone Networks has

lent its support to produce this Guide.

Visit our Web site at www.techguide.com

to view and print this Guide, as well as

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