Transcript MOD02_SC
LAN Hardware Overview Version A.01 H3065S Module 2 Slides 20 LAN Hardware Components A LAN is composed of several hardware components: • servers and workstations • LAN interface cards • transmission media • other network devices - repeaters - hubs B R B - bridges - switches - routers a67319 H3065S A.01 21 © 1999 Hewlett-Packard Co. Transmission Media Central copper conduit Plastic insulating jacket Twisted Pair Plastic insulating jacket Nonconducting insulator Coaxial Woven metal shield Central copper conduit Light-emitting diode or laser transmitter Terminator Fiber Optic Glass or plastic fiber insulator cable Photodiode receiver a67320 H3065S A.01 22 © 1999 Hewlett-Packard Co. LAN Topologies Star T Bus File Server Hub Ring T a67321 H3065S A.01 23 © 1999 Hewlett-Packard Co. LAN Access Methods Originating Workstation Token Recognizes destination address Copies message Sends token back to source Seizes token Changes status to frame Transmits data Receives token back Removes message Issues new token Token Passing CSMA/CD a67322 H3065S A.01 24 © 1999 Hewlett-Packard Co. IEEE 802.3 Standard Mainframe Workstation Packet travels in both directions Terminator Terminator Network Packet a67323 H3065S A.01 25 © 1999 Hewlett-Packard Co. IEEE 802.5 Standard Token circulates a67324 H3065S A.01 26 © 1999 Hewlett-Packard Co. FDDI Standard FDDI Dual Ring Dual Attachment Station (DAS) Primary Ring Secondary Ring Dual Attachment Concentrator (DAC) Single Attachment Stations (SAS) Router Backbone a67325 H3065S A.01 27 © 1999 Hewlett-Packard Co. Repeaters and Terminators Signal on wires R Terminator Terminators R Repeater Repeaters Terminator • Repeaters extend the network by propagating signal. • Repeaters Pass all traffic through without error checking. • Repeaters Pass errors and collisions through. Terminators • Terminators are required at each end of a bus LAN segment. • Terminators absorb the signal on the wire so it does not reflect back. a67326 H3065S A.01 28 © 1999 Hewlett-Packard Co. Hubs Hub Hubs • Network signal is automatically repeated across every port • Works like a multi-port repeater • Physical star topology; but is implemented as a logical bus topology • Can easily add/remove nodes without disrupting network • Errors and collisions are passed through • Usually uses twisted pair instead of coax for workstation connections a67327 H3065S A.01 29 © 1999 Hewlett-Packard Co. Bridges and Switches Card 1 080009-987654 Switch Address Table Card 1 Bridge Card 2 Card 2 080009-1A23C4 0060B0-7EF226 080009-987654 080009-234ABC 080009-23EF45 080009-1A23C4 080009-234ABC Bridges 080009-23EF45 0060B0-7EF226 • Bridges contain two or more separate interface cards and connect multiple segments on the same network. • Bridges forward frames based on the destination MAC address. • Bridges use “store and forward” to ensure no errors are passed onto another segment. • Bridges do not pass errors or collisions through to another segment. Switches • Switches work similar to a multiport bridge in that they connect multiple “collision domains”. • Switches can maintain simultaneous connections; multiple active circuits allow data to be forwarded in parallel. a67328 H3065S A.01 30 © 1999 Hewlett-Packard Co. Routers and Gateways Network 128.1.0.0 Network 15.0.0.0 Router Router Network 128.2.0.0 Gateway Network 192.1.1.0 Routers • Routers connect different networks and different LAN types. • Routers forward packets based on destination IP addresses. • Routers exchange routing information and use this information to build route tables. • Each router has a minimum of two LAN cards; each LAN card has its own IP address. • Routers do not forward broadcast packets; broadcast packets are dropped. Gateways • Gateways used primarily to implement wide area networks (WANs). a67329 H3065S A.01 31 © 1999 Hewlett-Packard Co. Pulling It All Together Dual FDDI Ring Router R Router Gateway R G G Switch B Bridge R Repeater B Hub Bridge Token Ring a67330 H3065S A.01 32 © 1999 Hewlett-Packard Co.