1© 2004, Cisco Systems, Inc. All rights reserved.

Module 8 Ethernet Switching

222© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idObjectives

333© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idThings to consider…

• Shared Ethernet works very well – within limits

• What things cause problems that reduce bandwidth in a shared environment?

444© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idLayer 2 Bridging

• A bridge can be used to create two collision domains

• Source MAC address of a frame and the associated incoming switch port are added to the address table

555© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idBridges

666© 2004, Cisco Systems, Inc. All rights reserved.

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Switch Operation

• Switch – a multiport Bridge

• Divides collision domain into many smaller collision domains

• Full-Duplex technology

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Full Duplex

888© 2004, Cisco Systems, Inc. All rights reserved.

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Network Latency

999© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idSpanning-Tree Operation

Multiple paths means that frames can loop

101010© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idSwitch Modes

• Store and Forward - A switch receives the entire frame before sending it out the destination port.

• Cut-Through - A switch starts to transfer the frame as soon as the destination MAC address is received.

• Fragment-Free - Read the first 64 octets only to obtain the header information

–Therefore misses the CRC for checking

111111© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idSTP States

Spanning Tree Protocol moves from blocking to listening to learning and then to forwarding or disabled.

121212© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idTypes of Networks

131313© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idCollisions in Collision Domain

141414© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idCollision Domain Segmentation

151515© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idIncreasing a Collision Domain

161616© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idLayer 1 Devices Extend Collision Domains

171717© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idLimiting the Collision Domains

181818© 2004, Cisco Systems, Inc. All rights reserved.

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Segmenting a Collision Domain with a Bridge

191919© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idBroadcasts in a Bridged Environment

202020© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idEffects of Broadcasts in a IP Network

212121© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idBroadcast Domain Segmentation

222222© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idData Flow Through a Network with a Router

232323© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idSegments

242424© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idWhat is a segment?

From the previous slide the three definitions of a segment are:

• Term used in the TCP specification to describe a single transport layer unit of information.

• Section of a network that is bounded by bridges, routers, or switches.

• In a LAN using a bus topology, a segment is a continuous electrical circuit that is often connected to other such segments with repeaters.

252525© 2004, Cisco Systems, Inc. All rights reserved.

www.pnj.ac.idSummary

For more info on switches check out

http://www.bellevuelinux.org/network_switch.html