High Speed Ethernet: Hubs, Switches, and Protocols, Study notes of Local Area Network (LAN)

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High Speed Ethernet

Dr. Sanjay P. Ahuja, Ph.D.

Professor

School of Computing, UNF

Hubs and Switches

LAN Protocols

IEEE 802.3 (Ethernet) Frame Format

IEEE 802.3z (Gigabit) Ethernet Configuration

Workgroup represents high-performance

workstations and servers.

The 100/1000 Mbps hub supports

workstations and servers and 100 Mbps

hubs via the 100 Mbps links and

supports 1-Gbps links for backbone

connectivity.

Gigabit Ethernet retains the CSMA/CD

MAC protocol and frame format as its

10 Mbps and 100 Mbps predecessors.

Gigabit Ethernet Physical Layer Options

1000BASE-LX uses long wavelength laser (1,270–1,355 nm) and is specified to work over a distance of up to 5 km over 10 μm single-mode fiber. This is preferred for campus backbones and similar applications. It can also run over all common types of multi-mode fiber with a maximum segment length of 550 m.

1000BASE-SX is a fiber optic gigabit Ethernet standard for operation over multi-mode fiber using a 770 to 860 nanometer light wavelength. The standard specifies a distance capability between 220 m (62.5 μm fiber) and 550 m (50 μm fiber). This standard is highly popular for intra-building links in large office buildings.

1000BASE-T (also known as IEEE 802.3ab) is a standard for gigabit Ethernet over copper wiring. Each 1000BASE-T network segment can be a maximum length of 100 m, and must use Cat 5 cable at a minimum. Cat 5e cable or Cat 6 cable may also be used.

1000BASE-CX is a standard for gigabit Ethernet connections with maximum distances of 25 m using shielded twisted pair (STP). It is used in equipment rack room.

Gigabit Ethernet Discussion

• In practice, no one is going to spend on Gigabit Ethernet cards to get high

performance and then connect the computers with a hub to simulate classic

CSMA/CD with its collisions.

• While hubs are cheaper than switches, Gigabit Ethernet cards are still

expensive. To then economize by buying a cheap hub and slash performance

of the new system is foolish. So both Carrier Extension and Frame Bursting

are moot since no one will use Gigabit Ethernet hubs. Only switches will be

used. But IEEE 803.z committee put them in for backward compatibility.

IEEE 802.3ae (10 Gbps) Ethernet Configuration

10 Gbps Ethernet

backbone pipes will

help relieve congestion

for workgroup switches,

where Gigabit Ethernet

uplinks can easily become

overloaded, and for

server farms, where

1-Gbps NICs are already

in widespread use.

10 Gbps Ethernet …

• The technology also allows the construction of MANs that connect geographically

dispersed LANs between campuses. Thus, Ethernet begins to compete ATM and other WAN technologies. Where the customer requirement is data and TCP/IP transport, 10 Gbps Ethernet provides substantial value over ATM transport for both network end users and service providers:

• No expensive, bandwidth consuming conversion between Ethernet packets and ATM cells is required; the network is Ethernet end-to-end.
• The combination of IP(v6) and Ethernet offers QoS and traffic policing capabilities that

approach those provided by ATM.

• A wide variety of standard optical interfaces (wavelengths and link distances) have

been specified for 10-Gbps Ethernet, optimizing its operation and cost for LAN, MAN, and WAN applications.

The goal for maximum link distances covers a range of applications: from 300 m to 40 km.

10 Gbps Ethernet Physical Layer Options

• 10 GBASE-S (short): For 850 nm transmission on multi-mode fiber; distance up to 300 m. (10GBASE-SR and 10GBASE-SW)
• 10 GBASE-L (long): For 1310 nm transmission on a single-mode fiber; distance up to 10 km. (10GBASE-LR and 10GBASE-LW)
• 10 GBASE-E (extended): For 1550 nm transmission on a single-mode fiber; distance up to 40 km. (10GBASE-ER and 10GBASE-EW)
• 10 GBASE-LX4: For 1310 nm transmission on a single-mode or multi-mode Fiber; distance up to 10 km. This uses WDM to Multiplex the bit stream across 4 light waves.

Note: The first three of these have two sub- options: “R” and “W”. The R implementations are designed for use over dark fiber, i.e. a fiber that is not in use and not connected to any other equipment. The W implementations are used to connect to SONET equipment (WANs).

10GBASE-SW, 10GBASE-LW, 10GBASE-EW are varieties that use the WAN (W) option are designed to interoperate with OC-192/SONETequipment using a A SONET frame running at 9.953 Gbps.

IEEE P802.3ba (100 Gbps) Ethernet

• Market drivers for 100 Gbps-Ethernet:
• Data Center/Internet media providers:

To support the growth of Internet multimedia content and web apps, content providers have been expanding data centers, pushing 10-Gbps to its limits. Likely to be high-volume early adopters of 100 Gbps Ethernet.

• Metro-video/service providers:

Video on demand has been driving a new generation of 10-Gbps Ethernet MANs. Likely to be high- volume adopters in the medium term.

• Enterprise LANs:

Continuing growth in convergence of voice/video/data is driving up network switch demands. Adoption of 100-Gbps is likely to be slow with main reliance on 1-Gbps/10-Gbps mix.

• ISP core routing:

With the massive amount of traffic flowing through these nodes, these installations are likely to be early adopters of 100 Gbps Ethernet.

100 Gbps Ethernet Configuration

Trend at large data centers, with substantial bank of blade servers, is the deployment of 10-Gbps ports on individual servers to handle massive amounts of multimedia traffic provided by these servers. This stresses on-site switches needed to connect large numbers of servers. A 100 Gbps rate provides the bandwidth to handle the increased traffic load.

100 Gbps will be deployed in switch uplinks inside the data center as well as providing interbuilding, intercampus, MAN and WAN connections for enterprise networks.

Multilane Distribution for 100 Gbps Ethernet