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White Paper

U nderst anding Intel l igent Carr ier EthernetBringing the Advantages of Ethernet to the Service Provider

Abstract

Ethernet has become the most successful and widely deployed LAN tr ansport technology

in the world. While other technologies such as Token Ring and Fiber Distributed Data

Interface (FDDI) have become obsolete, Ethernet has more than 100 million clients deployed

today, making it the standard interface for most network-capable devices.

The last 20 years have seen significant development of Ethernet technology from 10-Mbps

shared operation over t hick yellow cable, to switched operat ion over unshielded twisted

pair (UTP) at 10, 100, and 1000 Mbps. However, the most significant development from a

wide-area networking perspective has been fiber opt ic transmission at 100 M bps, 1 G bps,

and 10 Gbps at transmission distances from 2 kilometers (km) up to 2000 km using

long-haul dense wavelength-division multiplexing (DWDM) systems.

In parallel to these developments, Ethernet switching technologies have evolved from simple

2-port devices with forwa rding rates typically in the thousands o f packets per second to

todays modern switching systems that suppo rt h igh port densities, forwarding rates in the

millions of packets per second, and sophisticated wire-rate services. Additionally, the

economics of Ethernet make it an a ttractive proposition as a WAN tr ansport for service

providers.

Another advantage of Ethernet as a tr ansport is its suppor t of class of service (CoS) that

allows up to eight classes of service to be defined. From an enterprise perspective, the

ubiquitous nature and sympatheticCoS characteristics of Ethernet make Ethernet as a WAN

technology very attractive because the Ethernet WAN can be seen as an extension of the

campus LAN.

Ethernet uniquely supports true multipoint communications. Most WAN technologies such

as Frame Relay or ATM offer point-to-point connectivity only, which are complex to

configure as more connections are added. If a Virtual Private LAN Service (VPLS) is used, its

inherent broadcast na ture makes newly added locations ready to use because the routing

protocol will automatically detect neighboring devices and form routing adjacencies.

Although Metro Ethernet is often thought to be analogous to Transparent LAN Services,

Ethernet can be used as a broadband access technology to point-to-point Layer 2 VPN,

Layer 3 VPN, and Internet services.

For many of these same reasons, service providers are beginning to consider Ethernet a core

technology, if not a core service, for their WAN and metropolitan-area networ k (metro)

serviceofferingsas wellas a mechanism for offering numerous other services. When coupled


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with existing, well-known technologies such as SONET/SDH, IP, and Multiprotocol Label Switching (MPLS),

Ethernet has tremendous potential for providing high-bandwidth connectivity and service across the range of service

provider offerings.

This paper will introduce Ethernet as a metro networking technology and describe the various technologies and

services that can be enabled over an Ethernet infrastructure, including integration with established or emerging

technologies such as Resilient Packet Ring (RPR) and SONET/SDH.

Demands for Ethernet in the Service Provider Network

Most, if not all, service providers are looking closely at Ethernet as a technology within their service networks.

For example, incumbent local exchange carriers (ILECs); post, telephone, and telegraphs (PTTs); and interexchange

carriers (IXCs) are considering Ethernet, either as a pure Layer 2 tr ansport mechanism, or for offering IP VPN

services to complement their existing Frame Relay or ATMs services. A number of independent operating companies

(IOCs) are using Ethernet as a broadband technology for delivery of multiple services to the residential customer.

Additionally, there is an increasing trend involving the use of Ethernet as a backhaul instead of ATM for xDSL

applications. Cable companies themselves are using Ethernet as a means of aggregating cable headend systems. These

applications will be further discussed later in this paper.

But it is first importan t to understand what is encouraging the interest and demand for Ethernet in the service

provider space. These factors can be summar ized as:

Incremental services

Bandwid th

Availability of fiber

The enabling applications

Incremental Services

Ethernet isof interest to the service provider only if it provides a means for incremental revenue. In the past, Ethernet

wasoffered only as a custom service to large customers who had therequirement and were willing to payfor it. Now,

service providers are looking to Ethernet as a core transition medium for three main reasons: to enable new services,

to align business objectives and network infrastructure, and to customize the network for the end customer.

Ethernet first gained traction in the service provider space in 2001 dueto theincreased demand for transparent LAN

service. This service, while originally viewed as a niche service, has recently seen an upswing. Ethernet, by its nature,

allows a provider to offer this service, incremental to existing leased line or Frame Relay service, for additional

revenue. Another benefit of Ethernet, particularly in tandem with MPLS, is the ability to converge multiple services

onto a common transport medium. This isone of the primary benefits of a connectionless serviceinterface as opposed

to the current connection-based, point-to-point services offered today.

The speed and bandwidth characteristicsof Ethernet (discussed in the next section) allow the serviceprovider to offer

incremental and customized services more easily than previously possible. For instance, a particular end customer

might be looking for a voice service as well as a point-to-multipoint capability for video. The provider could offer a

voice service, while at the same time taking advantage of the broadcast nature of video and the intelligence of IP to

offer multicast video. All of this is run over a high-bandwidth infrastructure, helping mitigate the need for very

granular quality of service (QoS).


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Bandwidt h-Scaling Characteristics

One of the clear advantages of Ethernet isits ability to scalein bandwidth and speed. Whereas Ethernet began its lifeas a shared 10-Mbps medium over thick coaxial cable, it can now scale to switched 10-Gbps per link over fiber, with

100 M bps and 1 Gbps as interim steps. As Internet and Web-hosting traffic continue to grow, the ability to scale

bandwidth on a flexible platform, such as the Cisco Catalyst 6500 Series switches or Cisco 12000 Series routers,

becomes extremely attractive. For example, a 100-Mbps connection to a data center server can be easily upgraded

to a 1-Gbps connection, should that bandwidth be required. This is important because large networking servers can

now manage 100 Mbps to 1 Gbps of sustained throughput. Similarly, a networ k architect might also consider

upgrading the backbone links to 10 Gigabits Ethernet, something that can be done easily without costly equipment

upgrades or SON ET ring resizing.

In addition, the costs for Ethernet interfaces are often considerably less than those for more traditional technologies

such as packet over SONET (POS). Ethernet lacks some POS characteristics, such as 50-milliseconds (ms) link

restoration, that make POS so attractive to a service provider. However, many providers are willing to consider

Ethernet as a lower-cost means of connectivity, particularly if a SONET/SDH infrastructure is not already in place.

Product Availabilit y

Another trend that isclearly helping both Ethernet and IP is the availability of Ethernet interfaces on a wider variety

of equipment. Whereas five years ago, Ethernet could only be found on networ k interface cards (NICs), hubs, and

switches, it isnow found, in relativelyhigh densities, acrossmost switching and routing platforms. What iseven more

interesting are the other devices that can now connect to an Ethernet and/or IPnetwork. Theseinclude storage arrays,

WiFi access points, cable headend equipment, gaming equipment, and cameras.

The cost of Ethernet interfaces is dropping dramatically as they become more integrated into the end-user devices.

Most PCs now come with an onboard 100-Mbps or 10 /100/1000 interface. NICs can be purchased inexpensively.

An Ethernet interface on anything from a Sony Playstation to a video-on-demand quadr ature amplitude

modulation (QAM) modulator can be included easily and at little cost to the equipment manufacturer. The sheer

availability of Ethernet is increasing bandwidth for the enterprise and home user, thereby requiring the service

provider to increase its own bandwidth.

Availability of Fiber

Ethernet isdesigned to run over two media types: copper and fiber. Ethernet is usuallysent over copper cablebecause

the vast majority of Ethernet connections are from a switch to an end station. Longer-distanceEthernet transmissions

at gigabit or tens-of-gigabits rates require fiber-optic cable. Fortunately for the service provider, much of that fiber

already exists. In the 1990s many service providers, utilities, and government entities began trenchinga nd laying fiber

into the ground. While the expected demand for that fiber has not grown as quickly as expected, the infrastructure,to a large extent, exists and is waiting to be u sed.

While much of this fiber has been lit up with time-division multiplexing (TDM) or private-line access to their

customer base, many service providers have a large por tion of da rk fiber waiting to be used. Many providers are

looking to this fiber to carry incremental servicethis is where Ethernet broadband, often referred to as Ethernet to

the X (where X is business or residential), and Metro Ethernet can be deployed to offer new and innovative

high-bandwidth services. Many providers have fiber access to many large business parks and some residential areas

(though a residential offering is more common in high-density residential areas featuring many apartments). There


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is still a challenge, though, because fiber is not yet universal and offering fiber directly to the business can often

involve additional trenching. However, the availability of fiber in the collector rings, backbone rings, and long haul

has made Ethernet an attractive transmission medium.

The use of copper for Ethernet service delivery is becoming increasingly attractive, particularly considering the sheer

volume of copper already in the ground. Copper t oday provides the majority of last-mile technology for t elephone

and serial WAN connections, both for residential and business services. Fortunately, innovations in Ethernet, as well

its usage in retrofitting existing technologies, have helped enable copper access to Ethernet networks. Technology

such as Ethernet over very-high-bit-rate DSL (VDSL) is one mechanism that has been deployed in Europe and in

par ts of the United Stat es today. In addition, other technologies such as Digital Subscriber Line Access

Multiplexers (DSLAMs) with Ethernet uplinks and asymmetric DSL2 (ADSL2) are also aiding in the adop tion of

Ethernet in the last mile.

The Enabling Applications

Many enterprise network managers are seeing their data volume dramatically increase. This is due to a number o f

reasons, such as more peer-to-peer traffic, larger file transfers (either FTP or e-mail), and simply more use of the

Internet as a businesstool. Another, arguably more relevant factor that contributes to higher bandwidth, even though

the data volumesmay be low, isapplication transaction delay. Some modern applications actuallyrequire transaction

delays in the 50-ms range that can only be delivered using high-speed transport. However, these applications will

typically not compel a provider to dramatically rearchitect its network; instead, they will change the way in which

services including bandwidth are delivered. The providers, understandably, are looking for the next big thing. The

emerging applications may tip the balance in the service provider networks toward higher bandwidth and Ethernet

Storage

Enterprises are now more dependant than ever on their data, both transactional and backup. This has made storagenetworking a critical business requirement. While many transactional storage applications require synchronous

storage using dark fiber or DWDM, many backup, network-attached storage (NAS) and disaster-recovery solutions

can make excellent use of Ethernet as a transmission medium in the metro between data centers. Service providers

are beginning to notice this oppor tunity because it not only requires bandwidth, but a guaranteed service-level

agreement (SLA), something that they can charge back to their customers.

Video

Video providers, such as cable companies, are looking for less expensive ways of delivering data to their end users.

As many of these cable headend devices become Ethernet-attached to the aggregation layer of the network, more

bandwidth is required to transfer these now-digital files. In addition, multiplevideo streams per link can dramatically

increase bandwidth requirements, thereby generating more interest in cost-effective transmission. Ethernetssimplicity and affordability is appealing to video and cable providers.

Triple Play (Voice, Video, and Data)

Many service providers, particularly cable companies and IOCs, are seeking entry into existing markets by offering

more innovative services. Cable companies and IOCs typically have access to large amounts of fiber, enabling them

to offer broadband Ethernet service. By providing 10 Mbps to each residence, they can use that connection to offer

voice services, cable television (video) services, and Internet access. With bandwidth once again a factor, Ethernet

becomes a straightforward t echnology choice for deployment.


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Additionally, the advent of high-bandwidth ADSL2 that can support voice, video, and data will likely demand a

high-bandwidth Ethernet backhaul instead of the more tr aditional ATM backhaul networks. Given the copper

footprint in many mar kets, ADSL2 and Ethernet provide a complimentary solution to deliver high-bandwidth

services over copper and fiber.

The Cisco metro solution delivers the most comprehensive multilayer service portfolio for providers to quickly scale

customers and revenue. This portfolio can enable high-value services at any layer while providing a growth path to

a broader and more profitable service offering. Cisco Systems has developed its metro solution to tightly link into

enterprise environments that require integrated voice, video, and content applications. This integration allows service

providers to link to enterprise applications based on Cisco AVVID (Architecture for Voice, Video and Integrated

Data). The perspectivesprovided in this paper come from the considerable experience and success Cisco has achieved

in helping enterprise companies design and deploy their converged data networks.

Standards Development

Another important reason for Ethernet in the serviceprovider spacehas been the activity within the standardsbodies.

In 2001, t he Metro Ethernet Forum (MEF) group w as formed with the express mission of furthering the adopt ion

of service provider Ethernet, and Ethernet technologies in general, in the WAN space. Specifically, MEF has been

looking at the Ethernet services and service definitions, gathering agreement between Ethernet vendors and service

providers about how a particular service should behave. This allows Ethernet vendors and service providers to

best understand what the service will look like to the end customer. Finally, M EF has been evaluating carrier-class

Ethernet. Th is initiative seeks to specify the architecture, protocols, and management for Ethernet-based

transport networks.

MEF has been an excellent forum for discussion of these services and capabilities. It is the standardsbodies, however,

such as the IETF, the International Telecommunication Union (ITU), and the IEEE, that have begun work on the

standardization of these particular protocols. The IETF has been specifically involved in the development of a

multipoint Ethernet service architecture called Virtual Private LAN Service (VPLS) and Virtual Private Wire

Service (VPWS). The IEEE, which governs Ethernet and bridging standards with the 802 .3 and 802.1 committees,

respectively, has been working on standards such as Resilient Packet Ring (RPR) (with the 802.17 committee) and

Provider Bridges (802.1ad).

Cisco has also been heavily involved in the Ethernet over Transport Architecture initiative. The original initiative

created the G.etna draft, which is now further segmented into G.etoa, G.ethna, G.esm, and G.ethsrv. The

following work items are under study group:

G.eota (Ethernet over transport architecture)

G.ethna (Ethernet-layer network architecture)

G.esm (Ethernet over tr ansport Ethernet service multiplexing)

G.ethsrv (Ethernet over transport service characteristics)

G.smc (service management channel private line)

G.enni (Ethernet over transport network interface)

G.euni (Ethernet over transport user interface)

G.eequ (Ethernet equipment)


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The standards effort, and the pa rticipation and leadership of Cisco, are accelerating the adoption o f Ethernet as a

metro and WAN technology. As service providers see the commitment to making Ethernet carrier-class and its

availability to the enterprise, the interest in and use of Ethernet is expected to significantly increase.

Transporting Ethernet in a Service Provider Netw ork

The service provider environment is very diverse; there are numerous technologies and protocols available for use in

service creation and service delivery. The first step to understanding how Ethernet as a technology plays in the metro

is to understand how it fits into the general technology scheme. Figure 1 show s the hierarchy and interrelation

between the metro technologies.

Figure 1

Ethernet Related to Service Provider Technologies

As stated earlier, the critical enabler for Ethernet as a transmission media is the availability of fiber. For that reason,

fiber is shown as the foundation for all the technologies in Figure 1. H ow that fiber is used, meaning what

transmission technology is implemented, depends on a number of factors, such as installed base, how the fiber is laid

out, density of customers in a particular a rea, and the service being offered.

At this juncture, it is very important to point out t hat metro Ethernet or service provider Ethernet does not

necessarily imply that Ethernet is used end-to-end. As Figure 1 shows, Ethernet is one possible option as a transport

medium; however, Ethernet can also be run over SONET or RPR. This is a critical distinction in the discussion of

service provider Ethernet: Ethernet as the customer User-Network Interface (UNI) versus Ethernet as the transport.

As the Figure 1 demonstrates, both are possible.

Ethernet in the First Mile and Access into the Network

Access into the service provider network can also be provided via Ethernet, either from a business or a residence.

This technology is generally referred to as Ethernet in the First Mile (EFM). The media choices are straightforward:

There is either copper access, such as existing telephone wire or Category 5 unshielded twisted pair, or fiber.

Many multi-dwelling units have copper wiring that has been in existence for quite some time. The ab ility to make

use of this for Ethernet is one of the main attractions of Long-Reach Ethernet (LRE). LRE, which is offered on the

Cisco Catalyst 2950 LRE Series switches, supports between 5 and 15 Mbps of Ethernet t ransmission over existing

voice-grade cabling with a drive distance of up to 5000 feet, making it an ideal solution for in-building connectivity

IP / M PLS Control

Fiber

CWDM / DWDM

Resilient

Packet

Ring

Switched

EthernetSONET / SDH


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Figure 2

Sample Service Provider Fiber and SONET/SDH Layout

Figure 2 shows the typical physical topology of a service providers network. The topology is laid out in a ring

configuration with three distinct tiers. The access ring provides access out to the customer premises. In many cases,

an access ring willsupport only a singlecustomer, although there are caseswhere many customers could be supported

per ring, depending on the bandwidth allocated per access ring. The access rings are terminated at ring collector

nodes, which are interconnected via the access-collector ring. The access-collector ring aggregates multiple access

rings into a single fiber distribution frame. Finally, these access-collector rings are aggregated at a CO point of

presence (POP). Each CO POP is typically interconnected over a high-speed (OC-48 or 192 ring) inter-office and/or

regional ring.

The physical topo logy determines a number of importan t factors, each of which affects the design of the Ethernet

service network. These factors include:

Amount of fiber availableIn some cases, a provider has installed plenty of fiber cores. This means that some of

the cores can be used for tradit ional TDM traffic while others can be sold to the data port ion of the provider

as dark fiber.

Section of the businessThe transmission group in a service provider may be the group offering the Ethernet

service. In that case, they almost always want to use the infrastructure already there, namely SONET/SDH. The

service offered will most likely be an Ethernet private line with an end-to-end guaranteed SLA.

Customer densityIf there are few customers, it might make more sense to multiplex Ethernet over an O C-3

circuit than to run Gigabit Ethernet to each customer. Conversely, ifthere are numerous customers, using Ethernet

switching over da rk fiber might make the most sense.

The question now arises as to what technologies are available to offer Ethernet over the transmission medium. Once

the provider has decided on the service offering and understands the implications on the transmission network, the

options can be considered.

Main HQ

Branch

Office


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Scaling Fiber w ith Wavelength-Division M ultiplexing

Wavelength-division multiplexing (WDM) technology uses the physical characteristics of light to multiplexwavelengths (lambdas), or streams of light, at different frequencies on the same fiber. There are two main types

of WDM technology: coarse and dense. Coarse WDM , or CWDM, uses wider spacing between frequency bands,

allowing for fewer wavelengths, but at a lower cost because the granularity of the lasers doesnt have to be tightly

controlled. DenseWDM, or DWDM, is more sophisticated and, with a smaller spacing between wavelengths, allows

for more lambdas on the same fiber.

CWDM and DWDM Gigabi t Interface Converters

Cisco supports CWDM and DWDM technology in a gigabit interface converter (GBIC) form factor. This technology

brings many of t he benefits of WDM technology, such as fiber savings and bandwidth multiplexing, together with

the simplicity of Ethernet. The CWDM GBICs can be inserted into any standard GBIC slot on a Cisco Ca talyst

switching platform or GBIC-enabled router (such as the Cisco 7600 Series). Each GBIC is tuned to a wavelength onthe C-band (1550 nanometers spectrum); because eight wavelengths are supported, there are eight individual GBICs,

each tuned to a specific wavelength. Each wavelength is capable of sending a full 1 Gbps in each direction. For the

DWDM GBICs, up to 32 wavelengths are supported, using the 100-gigahertz grid. Unlike the CWDM GBICs, these

wavelengths can be amplified.

The second component of the CWDM solution is the optical add/drop multiplexer (OADM). These OADMs are

designed to take in the colored light from the GBIC and multiplex it with the other wavelengths over the trunk .

Each site would ha ve an OADM , either single lambda or multilambda, depending on the number of w avelengths

added or dropped. Figure 3 shows a typical CWDM Ethernet ring configuration. For the DWDM GBICs, the

Cisco ONS 15216 Metropolitan/Regional DWDM System can be used for the add/drop component. Either way, the

capability and architecture of t he network is the same.

Figure 3

CWDM/DWDM Ethernet Ring

Because each wavelength is essentially a point-to-point link, the logical topology is a point-to-point network across

a physical ring. This is much like an Ethernet over SONET deployment in that the physical and logical topologies

vary. Redundancy within CWDM is handled by the edge devices because CWDM simply provides virtual

point-to-point Ethernet connections across the physical-ring topology. The edge devices may use 802.1 Spanning Tree

2/2

2/1

0/1

0/2

East-Facing GBIC

West-Facing GBIC

Multiple l

Passive

CWDM Multiplexer

(Headend)

Single l

Passive

CWDM Multiplexer


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Protocol, 802.3ad C isco EtherChannel technology, or an IP rou ting protocol to provide redundancy. Each port

in the EtherChannel device is configured with a CWDM GBIC on the same wavelength; one port on the channel is

heading in the east direction on the ring, the other in the west direction. Thus, if there is a fiber cut somewhere

on the ring, EtherChannel technology will simply continue forwar ding on the active port in the direction where

connectivity still exists.

EtherChannel failover has been consistently measured at 200 milliseconds, considerably better than the 50

seconds with Spanning Tree Protocol [802.1d] and even the 2 seconds measured with Rapid Spanning Tree

Protocol [802.1w].

DWDM

DWDM is a far more robust technology, providingmore wavelengths than a CWDM solution. This enables a service

provider to better use the fiber plant by increasing the bandwidth potential of the installed fiber. DWDM is also

amplifiable to provide greater d rive distances between nodes. Most DWDM solutions, including the Cisco ON S15530 DWDM Multiservice Aggregation Platform and Cisco ONS 15540 ESP and ESPx extended services

platforms, provide support for up to 32 wavelengths, with each wavelength capable of supporting a single 10-Gbps

stream, multiplexed 1-Gbps stream, or Fibre Channel traffic. Figure 4 shows how DWDM can be used in a service

provider network to support Ethernet.

Figure 4

DWDM in a Service Provider Environment

Systems that support DWDM are typically more complex. To design a scalable DWDM network, t he network

architect must consider the dispersion and amplification characteristics of the network due to fiber as wellas distance

While CWDM has similar issues, only a few frequencies in the C-band can be amplified. In DWDM, amplification

and dispersion compensation must be stra tegically placed throughout the network to ensure signal integrity.

GRID Computing

Facility

Super Computing

Facility

Service

Provider

POP

Si

xDSL

ATM

Frame

Relay

Metro

DWDM

32 x 10 GE

Wavelengths


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Unlike CWDM, which uses the attached devices to provide the failure-recovery mechanism, DWDM provides these

mechanisms natively within the system. Using mechanisms such as splitter protection, which provides line card

protection with a special Y-cable, a D WDM system can reroute around a ring failure in 50 ms, the same as in a

SONET/SDH network.

Due to t he large amount of fiber in the ground today, most service providers are not using WDM strictly for fiber

savings. However, they are using WDM technology to efficiently scale bandwidth and provide rapid service

deployment. This is seen with the Cisco ONS 15540, which is often deployed in storage applications for data center

disaster recovery (both in enterprises and service providers). The Cisco ONS 15540 uses 10-Gigabit Ethernet

technology that, coupled with DWDM technology, delivers up to 320 Gbps of bandwidth over a single pair of fiber.

This capacity is then available for the service provider to offer LAN and storage area network (SAN) extension

between sites while making efficient use of the available fiber.

Another emerging application for DWDM and Ethernet is video on demand (VoD), which not only has large

bandwidth requirements, but also needs to be distributed to multipledistributed hubs located around the ring. In this

application, video tra ffic is sent from an Ethernet-connected VoD server over WDM and then distributed to the

headends serving customers. This gives the VoD provider the price advantage of Ethernet within their infrastructure

and the high bandwidth over single fiber gained from WDM .

Data-Optimized SONET/ SDH

In many cases, particularly with an incumbent provider, the installed fiber is carrying TDM traffic. This traffic is

essential a service providers business. These service providers already have SONET/SDH networks deployed and

have been offering services off them for a number of years. As providers look to offer incremental data services with

Ethernet over their existing infrastructure, they require the flexible technology that is found with a multiservice

provisioning platform (MSPP).

An MSPP is a platform that can transpor t traditional circuit-based TDM traffic such as voice, but a lso supports

native data services (such as switched Ethernet) that offer efficient and cost-effective services over SONET/SDH

infrastructure. The ability to integrate both capabilities allows the service provider to deploy a flexible, cost-effective

architecture that makes the best use of its existing investment while providing incremental services.

There are two ways of implementing data over this type of an infrastructure. First, the Ethernet-connected customer

could be mapped into a STS/VC circuit in a point-to-point fashion. Th is is often called book-ending because the

circuit originates on an Ethernet card in one location, such as a corporate headquarters, and terminates on another

Ethernet card at a satellite office. This one-to-one mapping does not, however, make the best use of bandwidth and

can be very inefficient. Consequently, Ethernet deployments over SON ET/SDH infrastructure have traditionally been

expensive.

Technology supported on the Cisco ONS 15454 MSPP provides data optimization via two main mechanisms. First,

the Cisco ON S 15454 M L Series line card provides integrated Ethernet switching in the SON ET/SDH platform.

Ethernet switching can then be used to mu ltiplex customers into the SON ET infrastructure. For example, say a

provider wants to offer service to 15 customers in a multitenant unit. Using the Cisco ONS 15454, the provider can

connect each customer via a 100-Mbps or 1-Gbps interface on the Cisco ONS 15454 ML Series line card. By using

the rate limiting and policing capabilities of the ML Ethernet switch, the provider can give a committed access rate

to each customer. That traffic is then mapped on the back end to STS-1, STS-3, or STS-12 circuits on the SONET/

SDH ring. This traffic can then be terminated at a service platform, which will be discussed later.


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Another important technology that makes better use of SONET/SDH is Resilient Packet Ring (RPR). RPR is defined

by the IEEE 802.17 committee, in which Cisco has been a major contributor. (RPR is based, in pa rt, on the Spatial

Reuse Protocol [SRP] developed by Cisco, and on Dynamic Packet Transport [DPT].) Cisco provides a scalable

solution for both Layer 2 and Layer 3 RPR. The implementation discussed here represents a Layer 2 implementation

over SONET or SDH. However, the Layer 3 version, traditionally called DPT, is available on high-end Cisco routers

for POP interconnect and other high-bandwidth, ring-based topologies. Figure 5 shows the basic operation of RPR.

Figure 5

Resilient Packet Ring Operation

In a multiservice provisioning platform-enabled SONET/SDH ring, RPR is an overlay and is processed by the

multiservice component of t he platform on a common circuit. Therefore, a single 1-Gbps circuit can support many

customers connected on ML Series cards on numerous Cisco ONS 15454 platforms around the ring. This provides

excellent bandwidth utilization while still providing fair access to all nodes on the ring. To gain further bandwidth

and ring efficiencies, an oversubscription factor can be applied to the ring, which is determined by the service defined

by the provider as well as the SLA offered to the end customer.

There are a number of other advances in dat a-optimized SON ET/SDH. One t echnology, Virtual Concatenation,

provides the ability to group several noncontiguous STS or virtual circuit fragments into a single larger virtual STS.

This virtual STS is referred to as a Virtual Concatenated Group (VCG) because it is made up of a group of smaller

STS, or VT, levels. Virtual Concatenation is used in conjunction with another scheme, Link Capacity Adjustment

Scheme (LCAS), which allow members of a VCG to be dynamically added o r subtracted to provide additional

bandwidth as required. Theseschemeshave now been finalized by the ITU(G.707 defines Virtual Concatenation and

G.7042 defines LCAS).

Ethernet over the Transmission M echanisms

It is import ant a t this juncture to po int out t hat, in most cases, the Ethernet topology (Figure 6), or the view from

the spanning tree or IP and MPLS perspective, may look considerably different than the physical SONET/SDH

network. Review Figure 2 and t hen evaluate Figure 6 for comparison.

Data and Control Packets

are Carried in Ring in

Opposite Directions

Physical Layer Initially

SONET/SDH Framing

(Ethernet and Optical Transport N etwork Possible)

Outer Ring

Cisco

ONS15454

Inner Ring

RPR Ring


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Figure 6

Ethernet Overlay on a Service Providers Physical Infrastructure

One of the most obvious differences between the physical infrastructure and logical one is the fact that, although the

physical network is laid out in a ring, the Ethernet network is a full mesh of point-to-point circuits. To access a

customer, for example, a single Ethernet connection will be mapped to a circuit, such as a 10-M bps port to a DS-3

circuit. Using the SONET/SDH ring protection mechanism means that there does not necessarily need to be dual

physical connections on the Ethernet side, because redundancy can be handled by SONET/SDH. Another important

consideration is the routing protocol. Its topology depends on the routers in the network and what adjacencies and

access exists. Therefore, a network administrator has to be familiar with the underlying transport as well as the

Ethernet and routed network.

Native Ethernet as a Transmission Medium

Although Ethernet can be overlaid on top of an existing transport infrastructure, such as dat a-optimized SONET/

SDH or DWDM, Ethernet switching can also be run over dark fiber end to end. There are some clear advantages to

this, namely the simplicity of Ethernet and the cost associated with Ethernet switching equipment. It is, however,

important to consider the unique characteristics of Ethernet when using it as a transmission medium. By using

SONET/SDH, for example, resiliency is provided by the transport mechanisms, such as bidirectional line switched

ring (BLSR) or unidirectional-path switched ring (UPSR) in SONET. Ethernet, over dark fiber, must use the schemes

inherent in Ethernet.

It is import ant t o understand at th is juncture that Ethernet at Layer 2 is radically different than traditional Layer 2

WAN and MAN protocols such as FrameRelay and ATM. One of themain differencesis that FrameRelay and ATM

both offer an intelligent forwarding mechanism (essentially a routing pro tocol) at Layer 2. For ATM, this protocol

is Private Network Node Interface (PNNI). Frame Relay uses a prop rietary routing protocol that uses PNNI,

although most Frame Relay cores are ATM-based. Switched Ethernet at Layer 2 has no such intelligence. It follows


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simple rules: forward the packet if the source and destination ar e known, flood the packet if the destination is

unknown , and learn t he address and forward the packet if the source was previously unknown. There is little

intelligence in this scenario. For this reason, IP or MPLS is typically used to scale the network to support thousands

of end customers.

Nat ive Ethernet uses two main topologies: point-to-point and ring (Figure 7). The choice between the two is often

predetermined by what exists in the ground (SONET/SDH or fiber layout) and cost. If a SONET/SDH network exists

already, then the Ethernet overlay network could be either hub-and-spoke over a physical SONET/SDH ring or could

use a shared r ing mechanism like RPR. The hub would reside at the PO P and provide aggregation for the spokes,

which are customer premises equipment (CPE).

Figure 7

Ethernet Topologies

If fiber rings exist, there are two methods of connecting Ethernet devices together: either daisy chaining devices

together in a ring, as shown in Figure 7, or using CWDM to provide virtual point-to-point Gigabit Ethernet circuits

over the physical ring as described earlier. The first method, used in many networks today, deploys native Ethernet

rings using the IEEE 802.1 Spanning Tree protocols. Ethernet rings are usually considered for deployment if the

following conditions exist: there is no SONET o r SDH already installed, and multiple customer p remises are

physically connected over the same fiber ring. Ethernet rings are particularly attractive to startup Ethernet providers

who ha ve installed their own fiber and are cost-conscious, and may consider Ethernet a low-cost alternative to a

transpor t infrastructure (SON ET, SDH, or DPT). However, there are a number o f issues to consider when dealing

with Ethernet ring scenarios.

Figure 7 shows a sample network architecture using Ethernet rings. From a technology perspective, Ethernet

switching at Layer 2 is not optimized in a ring configuration. This is in part due to the operation of the Spanning

Tree Protocol that is required by Ethernet to prevent loops in the network. Convergence times may be as short as 2

seconds with Rapid Spanning Tree Protocol [802.1w] and as long as 50 seconds with Spanning Tree Protocol

[802.1d].

Metro

POP


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Cisco, by working within the standards committees, has proposed numerous mechanisms to scale the capabilities of

Ethernet. These standards culminated in the recently standardized Rapid Spanning Tree Protocol [802.1w], which

can reduce convergence time considerably. This protocol is supported in the C isco Ca talyst 3550, Catalyst, 4500,

and Catalyst 6500 series switches as well as the Cisco ONS 15454 ML Serieslinecard. By using both Rapid Spanning

Tree Protocol [802.1w] and by managing bandwidth via the policing capabilities in the Cisco Catalyst switches, it is

possible to deploy a spanning tree ring in a standards-based, high-performance manner. Convergence has been

measured in the subsecond range for a ring of 10 switches.

The Service A ppl ication LayerBringing Int el l igence to Ethernet

So far, this paper has focused on how Ethernet can be used as a transmission medium from a customer site into the

service providers network. However, intelligence is a critical component of a carrier Ethernet network, bringing

availability, QoS for SLA enforcement, and network security to the service provider network.

The intelligenceprovided, typically in the POP or data center, allows the serviceprovider to offer not just connectivity

with an Ethernet User-Network Interface (UNI), but ISP peering, data center connectivity and aggregation, and

intelligent inter-POP connectivity.

Intelligence for Creating Carrier Ethernet

Carrier Ethernet must be built into a robust infrastructure capable of providing either the services a provider can

offer t o customers or a backbone infrastructure to support those services. Although the applications may vary, the

services themselves are the same. The primary services are:

Availability and redundancy

Quality of service

Secu rit y

Availability and Redundancy

Whether Ethernet is provided as a service or used as a backbone media, t he availability of the networ k is essential

to meeting customer SLAs or protecting the service providers backbone network from failure. Optical media, such

as SONET/SDH, have built-in protection schemes to reroute around failures. The Cisco O NS 15454, for instance,

supports UPSR and BLSR, which provide 50-ms convergence in the event of a line or path failure. Ethernet also

provides data-plane resiliency schemes required for path protection in t he event o f a failure. Cisco EtherChannel

technology, which was the foundation for IEEE 802.3ad, bundles Ethernet links to create both a higher-bandwidth

point-to-point physical connection as well as rapid failure (about 200 ms) in the event of a loss of a link within an

EtherChannel device. The Cisco Catalyst Family of switches supports Spanning Tree Protocol [802.1d], Rapid

Spanning Tree Protocol [802.1w], and Shared Spanning Tree Protocol [802.1s]. Unlike some proprietary Ethernetresiliency schemes, Cisco implementations of Spanning Tree Protocol provide standards-based protection

mechanisms, which can be measured from subsecond convergence in the event of a failure.

Many service providers today use IP or MPLS to scale their networks, either to offer Internet access or to provide an

MPLS VPN service to their customers. Those providers not using IP or MPLS today almost always have a roadmap

for how they will get there. The use of IP or MPLS (which requires an IP foundation) brings another set of resiliency

mechanisms that may be used to augment the availability of the networ k. Cisco IOS Software, which has been

developed over the past decade and deployed in most every service provider network in the wor ld, brings a robust


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set of rout ing protocols, such as Border Gateway Protocol (BGP), Open Shortest Path First (OSPF) Protocol, and

Intermediate System-to-Intermediate System (IS-IS) Protocol. These routing protocols, critical to determining reach

ability in the IP network, offer equal-cost load balancing and subsecond convergence. This is important for any

service, whether a VPN service or just Internet access.

Cisco pioneered Tag Switching in 1997, which became the foundation for todays MPLS. Cisco also innovated

numerous M PLS features, including Fast Rerout e and Traffic Engineering, to better manage bandwidth and

availability, and MPLSVPN to provide highlyavailable and efficient use of network resources as well as sophisticated

services. Cisco supports IP routing on all of its platforms based on Cisco IOSSoftware, ranging from the Cisco 800

and 1700 series routers to the Cisco 7600 and 12000 series routers , and also including switching platforms such as

the Cisco Catalyst 3550, Ca talyst 4500, and Catalyst 6500 series and the Cisco ON S 15454 M L Series. MPLS is

supported across most Cisco IOSrouters, from the Cisco 3600 Series to the Cisco 12000 Series routers, and is also

available on the Cisco Catalyst 6500 Series switches.

Quality of Service

QoS provides a means of guaranteeing bandwidth and service to one type of traffic over another. It allows service

providers to effectively manage their bandwidth usage and offer tiered traffic service levels. As service providers look

to differentiate themselves and offer SLAs to their customers, QoS becomes an important component in the network.

Many providers may choose to use a packet-based network a s the transpor t medium. Cisco switches and routers

provide a number o f mechanisms to ma nage how Q oS is applied to a packet as it tr averses a network. First, the

service provider may provide a certain data rate out to the customer. The provider can use the policing capability of

Cisco routers and Cisco Catalyst switches to limit the customers traffic and provide burst capabilities. These

functions are analogous to Committed Information Rate (CIR) and Peak Information Rate (PIR) capabilities within

Frame Relay and ATM networks. C isco pr ovides several mechanisms that support granular policing, from kilobits

per second to megabits per second. Once the traffic is in the p roviders network, a number of mechanisms can be

employed. First, some traffictypes, such as voice, have specific latencya nd jitter requirements. Strict priorityqueuing,

when used in conjunction with Weighted Round Robin (in the switching platforms) and Class-Based Weighted Fair

Queuing (in the routers), provides for bandwidth guarantees while also providing traffic differentiation based on IP

precedence or differentiated services code point (DSCP). QoS marking, reclassification, and queuing is handled in the

hardware of Cisco Catalyst switches and C isco 12000 and 7600 series routers without incurring performance

degradation.

Perhaps the easiest way to guarantee a customers traffic is to provide an end-to-end physical connection, such as an

Ethernet-based pr ivate line. The Cisco O NS 15454 allows mapping of an Ethernet UNI directly to an STS on a

SON ET network tha t guarantees end-to-end bandwidth within the network. H owever, many providers may be

interested in multiplexing multiple customers traffic streams onto a single STS to realize greater bandwidth

efficiencieswithin the network. By using the Cisco ONS 15454 ML Serieslinecard to an STScircuit, several customer

traffic streams can be aggregated and QoS policies applied such that if congestion is experienced, QoS can manage

the congestion and help ensure that SLAs are met. By using Resilient Packet Ring (RPR) on the Cisco ONS 15454

ML Series line card, fairness around the ring can be provided via RPR ring access fairness algorithms.


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Network Security

Whether the network is providing an Ethernet UNI or merely using Ethernet as a t ranspor t, the network must besecure from interna l and external att acks. Not only are unautho rized network -access cases on the rise, but the

sophistication of the attacks has increased tremendously. Service providers need to be concerned about not only

protecting their own networks from attack, but also protecting the integrity of their customers data. Unauthorized

access to a customers data or systems as a result of poor network security can hurt the providers business and may

also now have legal repercussions. For that reason, Cisco has developed a number of network security mechanisms

to protect Ethernet-based connectivity and service.

It is important to remember that Ethernet in itself, due to its simple forward and filter mechanisms, is not inherently

secure. A number of mechanisms in Cisco switches and routers have been put in place to ensure that the network is

as secure as possible. One simple mechanism, port security, can be enabled to limit the number of MAC addresses

that are learned per port. A static entry of a MAC address per port is also possible. This prevents unauthorized end

stations from appearing on the providers network. Cisco has also been helping lead the adoption of IEEE802.1x

port-based user authentication. Once the MAC address has been learned by the switch, 802.1x will authenticate the

user attempting network access. This provides an additional layer of network security by ensuring that only allowed

and authenticated devices are learned on the service provider network.

At Layer 3, Cisco provides a rich set of access control lists (ACLs), all supported in hardware, that enforces policies

on Layer 3 and 4 information. The switching mechanism used by Cisco switches and routers is called Cisco Express

Forwarding. While this in itself is not a network security mechanism, the fact that it uses topology-based switching

means that certain Internet wormsthat generate thousands of IP flows willnot adversely affect network performance

Cisco uses Cisco Express Forwarding across its entire line of routing and switching products. At Layer 2, Cisco also

provides sophisticated protection mechanisms to p rotect Spanning Tree Protocol, such as BPDUGuard and

RootGuard, wh ich enhance the overall security and availability of the network.

Ethernet VPN Services

If Ethernet is being offered as the UNI, the transmission medium, whether SONET, WDM, or Ethernet, gets the end

customers traffic into the providers network. When offering a VPN service to the enterprise, service providers need

to put mechanisms in place to create the VPN and scale it across the service providers infrastructure. To accomplish

this, a number of mechanisms can be used.

Tag Stacking

Tag Stacking, also known as Q-in-Q, provides a means of tunneling one set of VLAN tags by inserting a second

VLAN tag into the frame. This allows a service provider who is running a nativeEthernet switched network (in other

words, a network build entirely on Ethernet and Spanning TreeProtocol without IP or MPLS) to transparently tunnel

the customers VLANs from one site, through the serviceprovider cloud, to the second site.There are a few benefits

to this type of approach. The first benefit isthat the serviceprovider and customer VLAN tags do not need to match.

This eases the VLAN management and distribution for the service provider. Another benefit is that this approach is

inherentlymultipoint and provides a service that, to the enterprise customer, looks like an Ethernet segment. Because

Ethernet is inherently a broadcast-based medium, many pr oviders consider offering an Ethernet service that uses

these Ethernet capabilities. It should be noted that Tag Stacking is also less expensive and complex than MPLS

solutions and is very attractive from that perspective, although Spanning Tree Protocol limits the extent to which

a Tag Stacking network can grow.


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However, Tag Stacking, when used with technologies such as Ethernet over MPLS (EoMPLS), offers the best of both

worlds: scaling to very large networks as well as providing transparent multipoint LAN services. Available on the

Cisco 7600 Series, Cisco O NS 15454 ML Series, and Cisco Ca talyst 3550 and Catalyst 6500 series, this capability

allows VLAN transparency between the enterprise and service provider, between two enterprise end points. This

addresses one of the major enterprise applications, namely data mirroring and backup, which often requires the

servers at bo th sites to use the same subnet or VLAN.

Cisco is working within the IEEE 802.1 committee to standardize a mechanism of scaling bridging in the service

provider space. This draft, called Provider Bridges, is currently being evaluated in the IEEE and is also being

coordinated with efforts in other standards bodies, including ITU and IETF.

MPLS and M PLS VPN

As service providers worldwide have looked to scale their networks, MPLS has emerged as a highly scalable and

highly beneficial technology. Many Internet service providers (ISPs), particularly in Europe and Asia, have deployedMPLS to scale their networks. In addition, many interexchange carriers (IXCs) and post, telephone, and

telegraphs (PTTs) have MPLS networks deployed today. This enables service providers to both scale their networks

and offer MPLS VPNs to enterprise customers. Unlike the Layer 2 mechanisms discussed in the following sections,

MPLS VPN is a Layer 3 mechanism that provides enhanced network scalability, simplicity, and control. How do

MPLS VPN and Ethernet map together? Very simply: Ethernet can be used as a UNI to access MPLS VPN services.

In this case, the spigot delivered to the customer isa provisioned or managed Ethernet connection. Using Cisco IOS

routers such a s the Cisco 2600 , 3600 , or 3700 series, the customer-edge device is mapped into an Ethernet VLAN

that defines membership of a particular M PLS VPN. The Ethernet tagged frames will be transported over the

transmission infrastructure to a Cisco Cata lyst 6500 Series Supervisor Engine 720, or Cisco 7600 Series or 12000

Series provider-edge router where the Ethernet VLAN is subsequently mapped to a particular MPLS VPN. At this

point, advanced MPLS features such as traffic engineering and MPLS fast reroute can be used to better engineer the

customers network, adding potential service revenue to the provider.

Virtual Private Wire Service

With an MPLS network already deployed, either for integrating existing Layer 2 services such as ATM or Frame

Relay or for Layer 3 services, incremental services supporting Layer 2 Ethernet technologies can be deployed.

MPLS is beginning to be viewed as highly advantageous to Ethernet local exchange carr iers (LECs) and incumbent

LECS (ILECs) who are looking to provide Ethernet transport services to enterprise customers at Layer 2, while still

being able to scaletheir core architectures. The IETF has defined Virtual Private Wire Service (VPWS) as a mechanism

to provide Layer 2 connectivity, on a point-to-point basis, within a service providers MPLS cloud. Each

point-to-point circuit, or pseudo-wire, uses MPLS or Layer 2 Tunneling Protocol (L2TP) Version 3 to encapsulate

the nat ive header and send it across the M PLS cloud. For Ethernet, that mechanism is called Ethernet over

MPLS (EoMPLS).

The Cisco EoMPLS solution, based on an IETF draft standar d, is an extension of M PLS, which natu rally

complements the VLAN capability inherent in Layer 2 architectures. In its simplest form, EoMPLS provides an

emulated wire that is used to transport Layer 2 traffic across an MPLS-enabled Layer 3 core. This allows the service

provider the best of both wor lds: the scalability of an MPLS core without having to worr y about Spanning Tree

Protocol, and a Layer 2 transparent service offering.


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VPWS capabilities are offered on a variety of platforms, including the Cisco Catalyst 6500 Series and Cisco 7600,

10700, and 12000 series.

Virtual Private LAN Service

The lack of inherent multipoint capab ility in MPLS and the VPWS architecture has been brought to the forefront

by a number of service providers looking to offer an Ethernet M ultipoint Service (EMS), also referred to as a

Transparent LAN Service. Although it is widely acknowledged that the majority of Ethernet-based services offered

by the provider will be point to point (the way Frame Relay, SONET, and ATM work today), this capability is

still of tremendous interest. For tha t reason, Cisco has been working within the IETF on the Virtual Private LAN

Service (VPLS) drafts and within the IEEE to accelerate standards-based solutions for multipoint service delivery that

will allow for multivendor interoperability within t he industry.

A VPLSis an architecture that describes how Virtual Switch Instances may be interconnected using pseudo-wires to

form an emulated LAN service. A Virtual Switch Instance behaves, functionally at least, much the way a LAN switchwould. This architecture functions as an overlay onto the MPLS cloud. Cisco is committed to supporting VPLS as a

service offering on its switch and router platforms.

Residentia l Ethernet

In many places around the world, construction of new multi-dwelling units and tu rnover of infrastructure, such as

laying new fiber, is allowing Ethernet to become an alternative for broadband access. Instead of usingtelephone lines

for DSL or the coaxial cable for cable modems, fiber is run to the multi-dwelling units or, in some cases, directly to

the residence. Many providers, such as some PTTs and competitive LECs in Europe and Asia or Independent

Operat ing Companies (IOCs) in the United States, are looking to o ffer a t riple play service to the residential

customer, bundling voice services, video (cable TV and VoD), and data services (Internet access and Internet gaming).

Although voice and Internet access typically require little bandwidth of the network, video often requires significantbandwidth, hence the interest in Ethernet to the home.

Multicast

Internet access is handled by high-speed connectivity coupled with intelligent routing protocols such as OSPF and

BGP. Voice, which is not bandwidth-intensive, requires QoS to meet its latency and jitter needs. The third service in

the residential market, particularly one over Ethernet, isvideo. And to scale delivery of video and ensure the best uses

of the available bandwidth, the service providers network must suppo rt multicast.

Multicast, in its simplest definition, provides intelligent forwarding of IP video stream to the destinations that have

requested that stream. Unlike bridged broadcasts, which flood to all users in a VLAN or bridge domain, multicast

uses Layer 3 to request streams that may be available across an IP network to be forwarded to the requester.

Additional Layer 2 mechanisms, such as Internet Group Management Protocol (IGMP) snooping, in the Cisco

switches then ensure that the multicasts (which at Layer 2, by default, are treated as broadcasts) are forwarded

intelligently to their destination.

Cisco has wor ked over the past 10 years to develop numerous innovations related to mu lticast forwarding and

routing protocols. Multicast replication and forwarding is performed in hardw are at data r ates exceeding tens to

hundreds of millions of packets per second in Cisco switches and high-end rou ters (Cisco 7600 and 12000 series).

Forwarding, though, isonly part of theequation. Theother is thecomplex task of determining how to send multicast

data from the source to only those destinations that have requested the multicast stream.


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At Layer 2, IGMP snooping is a feature used to scan end-station IGMP Join messages and ensure that the return

data returns to only those ports that requested the stream. At Layer 3, multicast routing protocols are required to

build the multicast tr ee in the optimal fashion across the network . To accomplish this, Cisco innovated Protocol

Independent Multicast (PIM), a multicast routing protocol designed to operate over an IP network. PIM has proven

itself in numerous enterprise networks and is now deployed in some of the largest residential Ethernet deployments

in the world.

Multicast VLAN Registration (MVR) is another Cisco innovation that increases the efficiency of multicast transport

and is important for residential providers. MVR involves the creation of separate, dedicated VLANs constructed

specifically for multicast traffic distribution. Each Cisco Catalyst switch that receives an MVR stream will examine

each multicast group and interna lly bridge the multicast VLAN traffic to a particular subscriber that has requested

the multicast stream. This is yet ano ther feature Cisco has developed to help providers offer new and incremental

services to their customers.

Service Selection

As Ethernet moves from a niche residential application to a mor e mainstream broadband-access mechanism, the

ability of the provider to create and deploy services and bill customers accordingly is of tremendous interest to the

provider. Today, many providers are aggregating Ethernet UNIs at the customer premises back to an aggregation

switch or router in the POP. It is now possible to add more system intelligence by including Cisco Service Selection

Gateway (SSG) software on the Cisco Catalyst 6500 Series and Cisco 7600 Series.

Both the Cisco Catalyst 6500 Series and the Cisco 7600 Series are optimized for aggregating Ethernet traffic that has

been deployed in numerous Ethernet service networks and service provider backbones. By coupling the Cisco SSG

software with the Multiprocessor WAN Application Module (MWAM), a line card dedicated to broadband service

selection in the Cisco Catalyst 6500 Series and Cisco 7600 Series, the service provider can support such service

deployments as PPP Terminated, L2TP Access Concentrator, and L2TP Network Server. This allows for termination

of the session and then application of the appropr iate service.

The Cisco MWAM is a complete subscriber-management platform, providing basic subscriber services as well as

complete service-profile assignment and network routing. It enables the serviceprovider to offer a number of services

to their subscribers. These include integrated voice and data, IP television and VoD, differentiated Internet access

with QoS, and VPN access. This allows for the triple play to be offered to residential users. The provider can also

offer more advanced services to the residence, such as online gaming and multimedia services.

The service-selection capability also allows for additional capabilities, including:

Captive portal

Web-based subscriber authentication

Walled Garden Service creation

Micro billing services

Content filtering

Bandwidth on demand

E-learn ing


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Conclusion

Ethernet, the mainstay technology in the LAN, is now making its

way into the service provider networks, due to its high bandwidth,

price points, and flexibility. Ethernet deployment, both within the

service provider networks and as a service offering to the end

customer, is growing rapidly. Ethernet as a service-access technology

is also attractive; its sympathetic operation with enterprisenetworks

makes a service providers network appear as an extension of the

enterprises network. Ethernet has the added flexibility of being

transportableover the wide variety of technologies, such as SONET/

SDH, RPR, DPT, IP, and M PLS.

Cisco Systems is the only vendor that is able to integrate these

technologies into an architecture that allows service providers to

offer a rich service to their end customers. Cisco is uniquely

positioned to offer these capabilities by addressing both t he

transport and control planeoptions. From theCisco ONS transport

platforms to the Cisco Catalyst switches to the Cisco routers, Cisco

addresses the integration of transpor t technologies (SON ET,

Ethernet, and DPT) and offers years of expertise in Ethernet

switching, MPLS, and IP. As a result, Cisco delivers a single cohesivearchitecture to address service provider and enterprise requirements

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