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Modern Ethernet. Chapter 5. Objectives. Describe the varieties of 100-megabit Ethernet Discuss copper- and fiber-based Gigabit Ethernet Compare the competing varieties of 10-Gigabit Ethernet. Overview. Three Parts to Chapter 5. 100-megabit Ethernet standards Gigabit Ethernet standards

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  • Describe the varieties of 100-megabit Ethernet
  • Discuss copper- and fiber-based Gigabit Ethernet
  • Compare the competing varieties of 10-Gigabit Ethernet
three parts to chapter 5
Three Parts to Chapter 5
  • 100-megabit Ethernet standards
  • Gigabit Ethernet standards
  • 10-Gigabit Ethernet standards
ethernet facts
Ethernet Facts
  • There are only four Ethernet speeds: 10 mega-bit, 100 megabit, 1 gigabit, and 10 gigabit
  • Every version of Ethernet uses either unshield-ed twisted pair (UTP) or fiber-optic. (With a few, rare exceptions)
  • Every version of Ethernet uses a hub or switch, although hubs are incredibly rare today.
ethernet facts continued
Ethernet Facts (continued)
  • Only 10- and 100-megabit Ethernet may use a hub. Gigabit and 10-Gigabit Ethernet networks must use a switch.
  • Every version of Ethernet has a limit of 1024 nodes.
  • Every UTP version of Ethernet has a maximum distance from the switch or hub to the node of 100 meters.
    • 100BaseT4
      • CAT 3 or better cabling
      • Uses all four pair of wires
      • Disappeared from the market after 100BaseTX generally accepted
    • 100BaseTX
      • Dominant 100-megabit standard by the late 1990s
      • The term “100BaseT” now applies to this standard

100BaseTX Summary

    • Speed: 100 Mbps
    • Signal type: Baseband
    • Distance: 100 meters between the hub and the node
    • Node limit: No more than 1,024 nodes per hub
    • Topology: Star bus topology: physical star, logical bus
    • Cable type: Uses CAT5(e) or better UTP cabling with RJ-45 connectors
Upgrading 10BaseT network to 100BaseT
    • CAT 5 cable or better
    • Replace all old 10BaseT NICs with 100BaseT NICs
    • Replace 10BaseT hubs or switches with 100BaseT hubs or switches
    • Multispeed, auto-sending NICs and hubs/switches ease the upgrade
Multispeed, autosensing NIC
    • When first connected, it negotiates automatically with the hub or switch
    • If both do 100BaseT, they will use that mode
    • If the hub/switch only does 10BaseT, NIC does 10BaseT
Distinguishing 10BaseT NIC from 100BaseT NIC
    • Inspect closely
    • Look for something indicating the card’s speed
    • All modern NICs are multispeed and auto-sensing
    • UTP versus fiber-optic
      • UTP cannot meet the needs of every organization
        • 100-meter distance limit inadequate for large buildings and campuses
        • Lack of electrical shielding
        • Easy to tap
    • Fast Ethernet refers to all the 100-Mbps Ethernet standards

100BaseFX Summary

    • Speed: 100 Mbps
    • Signal type: Baseband
    • Distance: Two kilometers between hub and node
    • Node limit: No more than 1,024 nodes per hub
    • Topology: Star bus topology: physical star, logical bus
    • Cable type: Uses multimode fiber cabling with ST or SC connectors

Full-Duplex Ethernet

    • Early 100BaseT NICs were half-duplex
      • Could both send and receive data
      • But not at the same time
    • IEEE added full-duplex to the standard
      • Device sends and receives at the same time
      • By late 1990s, most 100BaseT cards could auto-negotiate for full-duplex
    • NIC and hub/switch determine full-or-half duplex
    • Setting can be forced through the operating system

IEEE 802.3ab called 1000BaseT

    • Most dominant Gigabit Ethernet
    • Four-pair UTP
    • Maximum cable length 100 meters
    • Connectors and ports look exactly like 10BaseT, 100BaseT

IEEE 802.3z known as 1000BaseX

    • 1000BaseCX
      • Twinaxial cable
        • Shielded 150-Ohm
        • Maximum length of 25 meters
      • This standard made little progress

IEEE 802.3z (continued)

    • 1000BaseSX
      • More common
      • Multimode fiber-optic cable
      • Maximum cable length 200 to 500 meters, depending on manufacturer
      • Uses 850-nm wavelength LED
      • Devices look exactly like 100BaseFX products
      • SC is the most common type of connection

IEEE 802.3z (continued)

    • 1000BaseLX
      • Long distance carrier
      • Single-mode (laser) cables
      • Maximum cable length 5 kilometers
      • Special repeaters increase distance to 70 kilometers!
      • Positioned as the Ethernet backbone of the future
      • Connectors look like 100BaseSX connectors

New Fiber Connectors

    • Problems with ST and SC connectors
      • ST connectors are large, twist-on
      • Installer must twist cable—danger of fracturing fibers
      • Techs have trouble getting fingers around closely packed connectors
      • SC connectors snap in and out, but are also large
      • Manufacturers wanted smaller connectors for more ports

New Fiber Connectors (continued)

    • Solution: Small Form Factor (SFF) connectors
      • Mechanical Transfer Registered Jack (MT-RJ)
      • Local Connector (LC)
        • Very popular
        • Considered the predominant fiber connector
      • Other fiber connectors exist
      • Only standards are ST and SC
      • Manufacturers have different connectors

Table 5.1

Gigabit Ethernet Summary

Standard Cabling Cable Details Connectors Length

1000BaseCX Copper Twinax Twinax 25 m

1000BaseSX Multimode 850 nm Variable – 220 – 500 m

fiber SC is


1000BaseLX Single- 1,300 nm Variable – 5 km

mode fiber LC, SC are


1000BaseT CAT 5e/6 Four-pair / RJ-45 100 m

UTP full-duplex


Introduction to 10-Gigabit Ethernet (10-GbE)

    • Showing up in high-level LANs
    • Expected to trickle down to the desktops in near future
    • New technology
    • Large number of fiber standards
    • Two copper standards
    • 10-GbE copper product available only since 2008

Fiber-base 10-GbE

    • IEEE challenge
      • Maintain the integrity of Ethernet frame
      • How to transfer frames at high speeds
        • Could use traditional Ethernet Physical layer mechanisms
        • Already a usable ~10 GbE fiber network (SONET) used for WANs

Fiber-base 10 GbE (continued)

    • IEEE Actions
      • A set of 10GbE standards using traditional LAN Physical-layer mechanisms
      • A set of 10 GbE standards using SONET infrastructure over WAN fiber
      • Recognized need for different networking situations

IEEE created several standards defined by

    • The type of fiber used
    • The wavelength of the laser or lasers
    • The Physical layer signaling type
    • Maximum signal distance (defined by previous factors)

Naming convention begins with 10GBasexy

    • x = type of fiber (usually) and the signal wavelength
    • y = Physical layer signaling standard
      • R for LAN-based signaling
      • W for SONET/WAN-based signaling

10GBaseSy uses a short-wavelength (850 nm) signal over multimode

Fiber-based 10GBaseSy Summary


10GBaseLy uses a long-wavelength (1310 nm) signal over single-mode

Fiber-based 10GBaseLy Summary


10GBaseEy uses an extra-long-wave-length (1550 nm) signal over single-mode fiber

Fiber-based 10GBaseEy Summary


10 GbE connectors

    • Standards do not define the type of connector
    • Manufacturers determine connectors

Copper-based 10GbE (10GBaseT)

    • 2006: IEEE standard for 10GbE running on UTP
    • Looks and works like slower versions of UTP Ethernet
    • Downside: 10GBaseT running on CAT 6 has maximum cable length of only 55 meters
    • 10GBaseT running on CAT 6a can to go to 100 meters

Table 5.2

10-GbE Summary

Wavelength /

Standard Cabling Cable Details Connectors Length

10GBaseSR Multimode 850 nm Not defined 26 – 300 m

/SW fiber

10GBaseLR Single- 1310 nm Variable – LC 10 km

/LW mode fiber is common

10GBaseER Single- 1550 nm Variable – LC, 40 km

mode fiber SC are


10GBaseT CAT 6/6a Four-pair / RJ-45 55 – 100 m

UTP full-duplex


10-GbE Physical Connections

    • Hodgepodge of 10-GbE types
    • Problem: single router may need to support several connector types
    • Solution: multisource agreement (MSA)
      • Modular transceiver plugs into10-GbE equipment
      • Converts between media types
      • Many competing media types recently
    • 10-GbE equipment exclusive domain of high-bandwidth LANs and WANs, including the Internet


    • Multispeed network works best for many situations
    • Series of high-speed switches create a backbone
      • No computers (except maybe servers) on the backbone
      • Each floor has its own switch connecting to every node on floor
      • Each floor switch has a separate high-speed connection to a main switch

Know Your Ethernets!

    • Know details of the Ethernet versions
    • Use summaries and tables
    • So far in the text, only the functions of a basic switch have been explained
    • More to see in terms of capabilities of switches