Modern Ethernet. Chapter 6

Transcription

1 Modern Ethernet Chapter 6

2 Contents Define the characteristics, cabling, and connectors used in 10BaseT and 10BaseFL Explain how to connect multiple Ethernet segments Define the characteristics, cabling, and connectors used in 100Base and Gigabit Ethernet

3 Historical Early Ethernet using a bus topology was very popular However, a break or bad connection anywhere on the network would bring the entire network down IBM unveiled a competing technology called Token Ring in the mid 1980s Used a physical star topology Any single break only affected a single station Substantial market share was being taken away from Ethernet in the second half of the 1980s

4 Ethernet s Response Ethernet manufacturers countered with an improved Ethernet Physical star for robustness Adopt inexpensive UTP cabling instead of the more expensive coax Same frame type of earlier versions for compatibility The new and improved Ethernet is called 10BaseT

5 10BaseT

6 10BaseT 10BaseT Speed 10 Mbps Signal Type Baseband A single signal on the cable Type of cable Twisted Pair

7 10BaseT Topology 10BaseT uses a physical star topology with each node connected to a central hub

8 10BaseT Topology The single segment is still there having been shrunk to the inside of the hub The hub is a multiport repeater operating at the Physical layer

9 Broken Cables If a cable running to a specific node breaks, it affects only that computer

10 Broken Hub If the segment inside the hub breaks, then the entire segment fails

11 Hub Sizes The main difference between hubs is the number of ports

12 UTP Unshielded Twisted Pair (UTP) 10BaseT requires CAT 3 (or higher), two-pair, UTP cable Installers usually install four-pair cable One pair sends data and one pair receives data

13 RJ-45 Connectors RJ-45 connectors are used on the ends of the cable Each pin in the connector connects to a different wire 8 pins numbered 1 through 8 Pins 1 & 2 send data; 3 & 6 receive data

14 Crimping A crimper is a tool used to secure an RJ-45 connector to the end of the cable Each wire must connect to the proper pin Color-coded wires are used Each pair has a solid and a striped wire

15 Wiring Standards Defined by the Telecommunications Industry Association/Electronics Industries Alliance (TIA/EIA) Two standards exist for four-pair UTP for 10BaseT networks T-568A T-568B

16 Wiring Standards Green/White Green Orange/White Blue Blue/White Orange Brown/White Brown EIA/TIA 568A standard EIA/TIA 568B standard Orange/White Orange Green/White Blue Blue/White Green Brown/White Brown

17 Split Pairs Two pairs of wires are used in 10BaseT 1 & 2 3 & 6 Why split the second pair (3 & 6)? This is to provide backward compatibility with telephone wiring Telephone cables use RJ-11 connectors A single line is wired using 2 & 3 A second line is wired using 1 & 4 An RJ-11 may be plugged into an RJ-45 outlet

18 Which Standard? Both 568A and 568B see wide spread usage The important thing is to be consistent within your organization

19 10BaseT Limitations Distance between hub and computer may not exceed 100 meters The maximum number of computers connected to a hub (or bank of hubs) is 1024

20 10BaseT Summary Speed: 10 Mbps Signal type: Baseband Distance: 100 meters between the hub and the node No more than 1024 nodes per hub Star bus topology: physical star, logical bus Uses CAT3 or better UTP cabling with RJ-45 connectors

21 10BaseFL 10BaseFL is a fiber-optic version of 10BaseT Uses pulses of light instead of electricity Longer distances up to 2 kilometers Immune to electrical interference More secure harder to tap into

22 10BaseFL Cable Uses fiber optic cable called multimode

23 10BaseFL Card

24 10BaseFL Summary Speed: 10 Mbps Signal type: Baseband Distance: 2000 meters between the hub and the node No more than 1024 nodes per hub Star bus topology: physical star, logical bus Uses multimode fiber optic cabling with ST or SC connectors

25 Connecting Ethernet Segments

26 Expanding the Network Additional hubs may be necessary When all the ports are used up on a hub To provide fault tolerance Hubs may connected using coaxial cable or crossover cables 10BaseT hub with BNC connector used to connect to another hub

27 Populated Segment A segment connecting two hubs may be populated by having one or more nodes connected to it

28 Crossover Cables Hubs may be connected using crossover cables In a crossover cable the send and receive pairs are reversed One end uses 568A and the other 568B

29 Crossover Ports To avoid rewiring some hubs have special ports that switch the wires inside the hub Uplink, crossover, in port, or out port all refer to a port where the wires have been reversed

30 Connecting Hubs When connecting two hubs together, use a crossover cable between two regular ports Or use a straight-through (normal) cable between a regular port on one hub and a crossover port on the other hub Some hubs have a button that switches a port between normal and crossover Two PCs may be connected by using a crossover cable from one NIC to the other NIC.

31 Hubs Connected by 10Base2

32 Broken Cables Segment C s failure prevents communication between segments A and B, but does not affect communication within segments A and B

33 5-4-3 Rule Multiple Ethernet segments connected together with hubs and repeaters form one large collision domain The rule limits the size of a collision domain

34 5-4-3 Rule In a collision domain no two nodes may be separated by more than 5 segments 4 repeaters 3 populated segments Populated segments have nodes attached Unpopulated segments, or link segments, connect other segments

35 5-4-3 Rule Here s a network with 6 segments that complies with the rule

36 High-Speed Ethernet

37 100Base Ethernet Fast Ethernet refers to any of several Ethernet flavors that operate at 100 Mbps

38 100BaseT IEEE supports two variations: 100BaseTX and 100BaseT4 100 means a speed of 100 Mbps Star bus topology UTP cabling and hubs 100BaseTX uses CAT 5e or better cabling and two pairs of wires 100BaseT4 uses four pairs of wires over CAT 3 or better cabling

39 Upgrading a Network The existing wiring (if it meets the CAT 3 or CAT 5e standard) may be used to upgrade a network Just change the NICs and hubs Networks may be upgraded gradually by using 10/100BaseT devices that may operate at either 10 or 100 Mbps 100BaseTX is often referred to as 100BaseT (since 100BaseT4 is rarely used)

40 Limitations of UTP Distance is a limiting factor for large campuses Lack of electrical shielding is a problem in locations with lots of electrical interference UTP cabling can be easily tapped into

41 100BaseFX 100BaseFX uses multimode fiber optic cable with SC or ST connectors Maximum cable length is 400 meters

42 Gigabit Ethernet Gigabit Ethernet is also called 1000BaseX Several standards have been defined 1000BaseSX, 1000BaseLX, 1000BaseT 1000BaseT, the dominant standard Uses four-pair CAT 5e or CAT 6 cable Maximum cable length is 100 meters Gigabit Ethernet usually means 1000BaseT

43 Ethernet Switches An Ethernet switch is a hub with a bridge built in Often called a layer 2 switch

44 Switched Ethernet Ethernet switches may be used to replace hubs for improved performance resulting in switched Ethernet Creates point-to-point links between devices to form single two-node collision domains essentially eliminating collisions Devices get full dedicated bandwidth

45 Backbone A backbone is a segment that connects other segments Backbones usually run at higher speeds than other segments

46 Full-Duplex Ethernet Full-duplex means that a device can send and receive data simultaneously Ethernet transmissions are half-duplex At any given time a machine can either send or receive data but not both Switched Ethernet uses different pairs of wires for sending and receiving allowing for fullduplex communication Essentially doubles the bandwidth

47 If a card supports fullduplex, its setup program will have an option to switch between half- and full-duplex Full Duplex