Router Components

Semester 2Chapter 4

Table of Contents

More on Components

The Show Command

Network Neighbor Routers

Basic Network Testing

More on Components

Configuration Details on RAM Router Modes

Table of Contents

External Configuration A router can be configured from four

separate sources: Console port (used to initially configure the

router) WAN/LAN links (attach through hub or switch

using a patch cable) Auxiliary port (needs a modem) TFTP server installed on the network

The easiest place to configure from is the console port. Attach a rollover cable from the router to your

computer COM1 or COM2 port Open HyperTerminal to log in

Internal Configuration

Review “Router Basics” section in Ch.2/3 Powerpoint.

RAM NVRAM Flash ROM

InterfacesConsoleAuxiliary

RAM NVRAM Flash ROM

InterfacesConsoleAuxiliary

As the router is booted, the following is loaded into RAM’s Working Storage.

RAM Specifics

RAMCommandExecutive

InternetworkOperating

System(IOS)

ProgramsActiveConfig

FileTables Buffers

Programs include the bootstrap program that • tests the equipment (POST) • and locates the IOS.

RAM Specifics

RAMPrograms

RAM Specifics

RAMInternetwork

OperatingSystem(IOS)

Programs

Once the IOS is located by the bootstrap program, it is loaded in to RAM.

RAM Specifics

RAMCommandExecutive

InternetworkOperating

System(IOS)

Programs

Part of the IOS is the Command EXEC. This is the program that translates the commands you type into a language that the IOS can understand.

RAM Specifics

RAMCommandExecutive

InternetworkOperating

System(IOS)

ProgramsActiveConfig

File

Once the IOS is initialized, it looks for an active configurations file (usually in NVRAM) and loads it. This file tells the router specifically what to do.

RAM Specifics

RAMCommandExecutive

InternetworkOperating

System(IOS)

ProgramsActiveConfig

FileTables

The tables are loaded from the configuration file including...• ARP Tables• Routing Tables

RAM Specifics

RAMCommandExecutive

InternetworkOperating

System(IOS)

ProgramsActiveConfig

FileTables Buffers

Finally, all leftover memory in RAM is used as the buffer for processing incoming and outgoing packets.

Router Modes

Good graphic. Learn it.

The Show Command

Table of Contents

Router Status Commands

On the next slide, you will see a graphic displaying the most common show commands.

Be sure to copy this graphic in your notes.

You need to know which component of the router the show command accesses and what each show command displays.

FlashNVRAMRAM

Internetwork Operating System

ProgramsActive

ConfigurationFile

Tablesand

Buffers

BackupConfiguration

File

OperatingSystems

Inte

rface

sRouter#show version Router#show flash

Router#show interfaces

Router#show processes CPURouter#show protocols

Router#show running-configRouter#write term

Router#show memRouter#show stacksRouter#show buffers

Router#show startup-configRouter#show config

Show Commands Defined show version -- displays the configuration of the system

hardware, the software version, the names and sources of configuration files, and the boot image

show startup-config (show config on Cisco IOS 10.3 or earlier) -- displays the backup configuration file

show flash -- shows information about the Flash memory device

show interfaces -- displays statistics for all interfaces configured on the router

show processes -- displays information about the active processes

show protocols -- displays the configured protocols; shows the status of all configured Layer 3 protocols

Show Commands Defined show running-config (write term on Cisco IOS

10.3 or earlier) -- displays the active configuration file

show memory -- shows statistics about the router's memory, including memory free pool statistics

show stacks -- monitors the stack use of processes and interrupt routines and displays the reason for the last system reboot

show buffers -- provides statistics for the buffer pools on the router

Lab

Before moving on, make sure you have completed… Lab 4.2.4-Router show commands

Network Neighbor Routers

Table of Contents

CDP

In order to fully understand how Cisco Discovery Protocol operates, do the lab. 4.3.5-CDP Neighbors

Basic Network Testing

Table of Contents

Multiple Testing Methods For a basic introduction to router

troubleshooting, do the labs. 4.4.2-Remote telnet access 4.4.3-ICMP Ping 4.4.4-Traceroute command 4.4.7-Show interfaces & clear counters 4.5.1-Troubleshooting tools challenge

Active mental participation in answering lab questions is crucial to do well on the test.

You will also retain the knowledge longer if you think about what you are doing and why!