This document summarizes key aspects of Ethernet LANs and Cisco switches. It discusses how switches can segment Ethernet networks into multiple sections using forwarding, filtering, and flooding functions. It also explains that while microsegmentation and hierarchies can improve switched Ethernet performance, physical loops must be prevented using Spanning Tree Protocol (STP). Finally, it outlines the startup process for Cisco switches and how the Cisco IOS CLI is used to configure settings like the switch name, passwords, interfaces, and IP addresses to implement a network design.

1. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-1
Module Summary
 Ethernet cables and segments can span only a limited physical
distance, but there are devices, such as repeaters and hubs,
that can be added to an Ethernet LAN to extend segments.
 Bridges and switches divide a LAN into multiple segments.
However, switches operate at much higher speeds and
support more advanced functionality, performing three major
functions in segmenting an Ethernet network: forwarding,
filtering, and flooding.
 There are a number of ways in which the performance benefits
of switched Ethernet LANs can be enhanced, including
microsegmentation and connectivity hierarchies; however,
there is the potential for intentional or unintentional physical
loops that can be solved by STP.

2. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-2
Module Summary (Cont.)
 The Cisco IOS CLI is used to communicate the configuration
details that implement the network requirements of an
organization.
 The startup of a Cisco Catalyst switch requires verifying the
physical installation, powering up the switch, and viewing the
Cisco IOS Software output on the console.
 The CLI is used to configure the switch name and passwords and
to enter console commands such as router interfaces and IP
addresses.
 Increase switch security by enabling password and port security
 Most port access problems can be verified using the show
interface command.

3. © 2007 Cisco Systems, Inc. All rights reserved. ICND1 v1.0—2-3