Institute of Technology,Sligo Dept of Computing

Cisco Semester 4

Chapter 1, version 2.1.3

Review

Overview

Chapter 1 is a review of the following subjects:

1.2 LAN Switching

1.2 Virtual LANs

1.3 LAN Design

1.4 Routing Protocols

1.5 Access Control Lists

and 1.6 IPX Routing

1.1 LAN Switching

1.1.1 Congestion and Bandwidth

As more people utilize a network to share large files, access file servers and connect to the Internet, network congestion occurs. To relieve network congestion, more bandwidth is needed or the available bandwidth must be used more efficiently.

1.1 LAN Switching

1.1.2 Why Segment LANs?

By using segments in a network, less users &

devices are sharing the same bandwidth when

communicating within the segment.

This process of creating smaller collision and

broadcast domains is referred to as

segmentation.

1.1 LAN Switching

1.1.3 Segmentation with LAN Switches

A LAN that uses a switched Ethernet topology

creates a network that behaves like it only has two

nodes - the sending node and the receiving node.

They share the 10Mbps bandwidth between them,

which means that nearly all the bandwidth is

available for the transmission of data.

1.1 LAN Switching

1.1.4 LAN Switching Overview

Switching increases the bandwidth available on

a network by creating dedicated network

segments and connecting those segments in a

virtual network within the switch. This circuit

exists only when two nodes need to

communicate.

1.1 LAN Switching

1.1.5 How a LAN Switch Learns Addresses

Switches learn device addresses by:

Reading the source address of each

packet transmitted

Noting the port where the frame was

heard

1.1 LAN Switching

1.1.6 Symmetric Switching

A symmetric switch provides switched

connections between ports with the same bandwidth, such as all 10 Mbps or all 100 Mbps ports.

1.1 LAN Switching

1.1.7 Asymmetric Switching

An asymmetric LAN switch provides

switched connections between ports of unlike bandwidth, such as a combination of 10 Mbps and 100 Mbps ports.

1.1 LAN Switching

1.1.8 Two Switching Methods

Store and Forward - (entire frame is received)

Cut-through - (destination MAC address is read)

Fast Forward - No error checking

and Fragment Free - Checks for collisions