STRUCTURED CABLING: Ethernet All the Way

The IEEE 802.3ae standard ratified in 2002 for 10 Gigabit Ethernet represents

a significant milestone in the evolution of Ethernet technology and provides a

tenfold performance increase over 1 Gigabit Ethernet. While Ethernet has been

dominant in the LAN, the advent of 10G Ethernet dramatically expands

applications for Ethernet beyond LANs into metropolitan-area networks and WANs.

The new 10G Ethernet preserves the current Ethernet semantics, including

minimum and maximum frame size, and frame format. Unlike 1 Gigabit Ethernet,

however, 10G Ethernet supports full-duplex transmissions only and initially

worked only with optical media. However, a standard ratified by IEEE early this

year offers a choice of copper-based interfaces for 10 Gigabit Ethernet now

using four twin-axial copper cable pairs, same as the one used by InfiniBand or

fiber channel. Meanwhile the work on 10GBase-T to run 10 Gigabit Ethernet over

twisted pair is ongoing in the industry.

The 802.3ae specification defines two sets of physical interfaces for 10G

Ethernet called the LAN and WAN physical interfaces. Some of the most important

LAN physical interfaces are:

• 10Gbase-SR - 850 nm serial interface with a range of 300 meters over
  
  multimode fiber.
• 10Gbase-LR - 1,310 nm serial interface with a range of 10 kilometers over
  
  single-mode fiber.
• 10Gbase-ER - 1,550 nm serial interface with a range of 40 kilometers over
  
  single-mode fiber.
• 10Gbase-CX4 — a copper based interface with a range of 15 meters.

The 802.3ae specification also includes a WAN PHY definition

that operates at a data rate compatible with a payload of OC-192c SONET/SDH. The

WAN PHY allows transport of Ethernet data using SONET/SDH infrastructure for

Layer 1 transport, while preserving the Ethernet format at Layer 2 eliminating

any protocol conversions associated in traditional Packet over SONET/SDH (PoS).

The WAN PHY interfaces also provide the same distance ranges as the LAN

interfaces.

Using

the 10G Ethernet WAN PHY lets service providers use existing SONET/SDH add/drop

multiplexers or repeaters to transport Ethernet traffic. But the 10G Ethernet

WAN PHY avoids the costly aspects of the traditional OC-192c SONET/SDH, such as

stringent grid laser specifications, jitter requirements and stratum clocking.

All the existing Ethernet standards, such as 802.1q for

virtual LANs, 802.1p for traffic prioritization and 802.3ad for link

aggregation, also apply to 10G Ethernet. This makes the deployment of 10G

Ethernet simply a plug-and-play situation for most corporations and service

providers with Ethernet networks.

10G Ethernet applications



In LANs, where Ethernet is dominant, the immediate application for 10G

Ethernet is in the LAN backbone. With 100M bit/sec Ethernet to each desktop and

1 Gigabit Ethernet connecting the wiring closet switches to the backbone

switches, 10G Ethernet provides a scalable connection between the LAN backbone

switches. With processor speeds now reaching 3 GHz and beyond, coupled with the

rapid price decline in Gigabit Ethernet network interface cards, which are now

in the $100 range, most servers come standard with Gigabit Ethernet network

interface cards. 10G Ethernet provides a scalable uplink from the data center

switches that connect server farms with Gigabit Ethernet copper interfaces.

Certain select enterprise verticals such as entertainment and animation are

deploying Gigabit Copper to each desktop to foster faster productivity and

collaboration between artists. 10 Gigabit Ethernet becomes vital for such

verticals to scale the LAN backbone and network aggregation layers. In most

cases, 10GBase-SR and 10GBase-LR will suffice the distance range needed for the

Enterprise LAN applications.

10G Ethernet provides a scalable uplink from the data center switches that connect server farms with Gigabit Ethernet copper interfaces

In Metropolitan Area Networks or MANs, many service providers

take advantage of the price/ performance and simplicity of Ethernet to provide

cost-effective, scalable broadband Ethernet services. New industry organizations

such as Metro Ethernet Forum (MEF) coordinate the efforts between vendors and

service providers to enable mass rollout of Ethernet services to business and

residential customers. Examples of Ethernet services to businesses include eLine

or Point-to-Point VPN service and eLAN or multipoint-to-multipoint VPN service

that offer a low-cost, simple and high-speed alternative to existing ATM or

Frame Relay services.

The 10Gbase-LR and 10Gbase-ER interfaces are cost-effective

10G bit/sec options for building ring or mesh topologies in MANs. By coupling

with 802.3ad-based link aggregation, metropolitan service providers get an

aggregate bandwidth of up to 80G bit/sec between two metropolitan routers. Some

vendors also offer proprietary innovations for rapid protection in metro ring or

mesh topologies while using standards based 10G Ethernet interfaces, in addition

to the new 802.1w based Rapid Spanning Tree implementations.

For WAN applications, the 10G Ethernet WAN PHY lets service

providers use existing SONET infrastructure, such as SONET/SDH add/drop

multiplexers and repeaters, protecting their current investment in SONET/SDH

gear. Because the 10G Ethernet WAN PHY avoids many of the costly attributes of

SONET/SDH, it offers a compelling alternative to traditional OC-192c SONET/SDH

interfaces with much better price/performance. 10 G Ethernet WAN PHY also allows

direct connection DWDM systems with OC-192c interfaces. Recently, leading

research institutions created the world's longest native Ethernet connection

by using 10G Ethernet WAN PHY from Japanese Data Reservoir project to the CERN

research center in Geneva, Switzerland, spanning approximately 18,500

kilometers, and 17 time zones. Using the 10G WAN PHY technology, a local area

network connecting computers at the University of Tokyo was extended to include

computers at CERN in Geneva so that they all appeared to be on the same LAN.

While 10G Ethernet products have now been shipping since

2001, 10G Ethernet market size in worldwide revenue is expected cross $1 billion

mark by 2006. Compared to 2003, the market size this calendar year is expected

to quadruple to $358 million. Price per 10G Ethernet port has come down from

$40,000 during the initial product shipments to $2,500 this year. Coupled with

the momentum in 1 Gigabit Ethernet over copper market, 10G Ethernet is

strengthening the wave of technology migration in the industry offering

scalable, efficient and unified network architecture for enterprises and service

providers.

Chandra Kopparapu, V-P, strategic marketing and

business development, Foundry Networks