Rivier College CS575: Advanced LANs Gigabit Ethernet

CS575 Gigabit Ethernet 1

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Rivier CollegeCS575: Advanced LANs

Gigabit Ethernet

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2Gigabit EthernetCS575

Overview

0 What is Gigabit Ethernet?0 Why Gigabit Ethernet0 Physical Layer Technologies0 Functional Elements of Gigabit Ethernet Technology0 Performance Issues0 Gigabit Ethernet Migration and Application Environments0 Vendor Implementation Examples


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What is Gigabit Ethernet?

0 An extension to 10 Mbps and 100 Mbps IEEE 802.3 Ethernet0 Offering 1000 megabits per second data rate0 An emerging IEEE 802.3z Ethernet standard0 The first draft of the standard was produced by IEEE in January

19970 The final standard was approved in June 19980 Can be implemented in either hubs (repeaters) or switches0 The hub is a shared medium technology (medium access control

such as CSMA/CD is needed) and the switch is a dedicated medium technology (no medium access controls are needed)

0 Allows half-duplex (HDX) and full-duplex (FDX) operation at speeds of 1000 Mbps (2000 Mbps effective throughput for FDX)

0 Expected to be deployed initially as a backbone network as well as for high speed server connections


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What is Gigabit Ethernet? (concluded)

0 Evolutionary high speed network using existing standards and proven technology

0 Compatible with existing Ethernet- Unchanged Ethernet MAC Layer (CSMA/CD) protocol - Unchanged Ethernet frame format and frame size (both

maximum and minimum)0 Support existing star-wired topology0 Support existing Ethernet applications


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Why Gigabit Ethernet?

0 Faster and more power computers continues to grow0 The need for gigabit LAN backbone to interconnect faster LANs

such as Fast Ethernet0 Growing number of complex, time critical, and bandwidth intensive

applications such large image file transfers0 Capability to support new applications and data types such as voice

and video0 Easy migration to higher performance levels (from wide installation

base of Ethernet/Fast Ethernet) without disruption (compare to ATM or other technologies)

0 Low cost of ownership including both purchasing cost and support cost

0 Internetworking and network design flexibility


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Applications Driving Network Growth

Source: Gigabit Ethernet Alliance

Application Data Types/Size Network TrafficImplication

Network Need

Scientific Modeling,Engineering

Data Files 100's of megabytes to

gigabytes

Large files increasebandwidth required

Higher bandwidth fordesktops, servers, andbackbone

Publications, Medical DataTransfer

Data Files 100's of megabytes to

gigabytes


Higher bandwidth fordesktops, servers, andbackbone

Internet/Intranet Data files now Audio now Video is emerging High transaction rate Large files, 1 MB to

100 MB


Low transmissionlatency

High volume of datastreams

Higher bandwidth forservers, and backbone

Low latency

Data Warehousing,Network Backup

Data Files Gigabytes to terabytes


Transmitted duringfixed time period


Low latency

Desktop VideoConferencing, InteractiveWhiteboarding

Constant data stream 1.5 to 3.5 Mbps at the

desktop

Class of servicereservation

High volume of datastreams


Low latency Predictable latency


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Physical Layer Technology

0 The Physical Layer technology for Gigabit Ethernet is mainly based on the ANSI X3T11 standards for Fibre Channel

0 Since Fibre Channel technology has been in use for for several years, the IEEE 802.3z standards committee decided to adopt this technology to reduce development time and risk for the Gigabit Ethernet standard

0 Four physical media types are defined for Gigabit Ethernet- Single mode fiber- Multimode fiber- Shielded twisted pair cable (STP)- Unshielded twisted pair (UTP-5) cable

0 Two Physical Layer standards- 1000BASE-X (IEEE 802.3z)- 1000BASE-T (IEEE 802.3ab)


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Physical Layer Technology (continued)

0 1000BASE-X is based on Fibre Channel Physical Layer standard- Three media types included in 1000BASE-X

=1000BASE-SX: Short wavelength (850 nm) laser on multimode fiber

=1000BASE-LX: Long wavelength (1300 nm) laser on single mode and multimode fiber

=1000BASE-CX: Short haul copper “twinax” STP- 1000BASE-SX is targeted at lowest cost multimode fiber runs

in horizontal and shorter backbone applications- 1000BASE-LX is targeted at longer multimode building fiber

backbones and single mode campus backbones- 1000BASE-CX is used for interconnection of equipment within

a short distance (25 m) in a computer room- Based on Fibre channel’s 8B/10B encoding (25% overhead)- 1.25 Gbps wire speed to achieve 1 Gbps data rate


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Cable Type Distance

Single-mode Fiber (9 micron) 5000 m using 1300 nm laser (LX)Multimode Fiber (62.5 micron) 275 m using 850 nm laser (SX)

550 m using 1300 nm laser (LX)Multimode Fiber (50 micron) 550 m using 850 nm laser (SX)

550 m using 1300 nm laser (LX)Short-haul Copper 25 m

1000BASE-X Cable Type and Distances



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0 1000BASE-T Standard- A standard (IEEE 802.3ab) for Gigabit Ethernet over 4 pairs of

Category 5 UTP for distance up to 100 meters- Based on the specifications of ANSI/TIA/EIA-568A (1995)- No need to replace existing Category 5 cabling (conforming to

1995 ANSI/TIA/EIA-568A standards) to use 1000BASE-T- Any link supporting 100BASE-TX should support 1000BASE-T- Installed cabling should be tested for return loss (echo), caused

by impedance mismatches (typically the fault of of poor connectors) and far-end crosstalk (signal leakage from adjoining wire pairs at the far end of the transmitter creates electrical noise)

- Uses a symbol rate of 125 Mbaud- uses a more sophisticated 4-dimensional, 5-level Pulse

Amplitude Modulation (4D-PAM5) coding scheme


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Physical Layer Technology (concluded)

- 4-levels to achieve 2 bits per symbol and the fifth level for Trellis Froward Error Correction coding

- Supports FDX on each pair of Category 5 UTP


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Functional Elements of Gigabit Ethernet Technology

Media Access Control (MAC)Full duplex/ Half duplex

Gigabit Media Independent Interface (GMII)

1000BASE-X 8B/10B Encoder/Decoder

1000BASE-T Encoder/Decoder

1000BASE-T UTP

Category 5Tranceiver

1000BASE-CX Shielded Balanced

CopperTranceiver

1000BASE-SX SWL

Fiber OpticTranceiver

1000BASE-LX LWL

Fiber OpticTranceiver

100 m25 m50 u MMF - 550 m62.5 u MMF - 220 - 275m

9 u SMF - 5km50 u MMF - 550 m

62.5 u MMF - 500 m802.3ab

physical layer802.3z physical layer

Ethernet Upper Layers


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Performance Issues

0 Limitations of shared medium (HDX) Gigabit Ethernet- Without modification to the Ethernet MAC layer protocol, the

maximum network diameter/size of Gigabit Ethernet is limited to about 20 m

- To keep the maximum network diameter/size of Gigabit Ethernet to 200 m (same as Fast Ethernet), the minimum CSMA/CD carrier time and the Ethernet slot time have been extended to 512 bytes (should be 640 bytes)

- Packets smaller than 512 bytes have an extra carrier extension- If all traffic consisting of 64-byte frames, the effective

throughput would drop to 120 Mbps- The Gigabit Ethernet throughput would be between 300 - 400

Mbps for average frame size on most Ethernet in the 200- 500-byte range


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Performance Issues (continued)

0 Gigabit Ethernet switches must be used to extend network size0 Not appropriate for seamless integration of LAN, MAN, and WAN0 Doesn’t deliver the QoS guarantees needed by multimedia

applications0 Working on standards to provide Quality of Service (QoS) and

Class of Service (CoS) to IP traffic0 Use 802.1Q/p to provide priority information for frames in the

network0 Use 802.3x for flow control0 QoS support by switch vendors such as Foundry Networks

- Policy-based traffic classification on=Type of Service (ToS)=IP precedence mapping=Layer 2/3/4 defined traffic flow


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Performance Issues (continued)

- Queue management=Strict Priority (SP) Queue=Weighted Fair Queue (WFQ)=802.1p queue mapping

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Performance Issues (concluded)

Source: Stallings: Data and Computer Communications

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Gigabit Ethernet Migration and Application Environments

Fast Ethernet Switch to Switch Links


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Gigabit Ethernet Migration and Application Environments (continued)

Upgrading Switch to Switch Links


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Fast Ethernet Switch to Server Links


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Upgrading Switch to Server Links


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Switched Fast Ethernet Backbone


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Upgrading Switched Fast Ethernet Backbone


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Shared FDDI Backbone


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Upgrading Shared FDDI Backbone


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Gigabit Ethernet Migration and Application Environments (concluded)

Upgrading High-Performance Desktops


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Examples of Gigabit Ethernet Switches

Lucent P550 Cajun Switch Extreme BlackDimaond Gigabit Ethernet Switch

Foundry BigIron 4000 Gigabit Ethernet Switch

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Enterprise-Campus Network Example

Source: Foundry Networks

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Traditional Router and Hub Campus Intranet

Source: Cisco White Paper

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Traditional Campus Wide VLAN Design


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Campus Wide VLAN with Multilayer Switching


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Multilayer Model with Server Farm



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W. Stalling, Local and Metropolitan Area Networks, 6th edition, Prentice Hall, 2000, Chapter 7

References

W. Stalling, Data and Computer Communications, 6th edition, Prentice Hall, 2002, Chapters 13-14

A. Wu, Advanced Local Area Networks, Lectures & Slides, Rivier College, 2001.

Documents

Rivier College CS575: Advanced LANs Gigabit Ethernet