Router ComponentsRouter Components

Router ComponentsRouter Components

Back panel of router Router Booting Sequence. Router Modes of operation.

Table of Contents

ROUTER ROUTER BACKPANELBACKPANEL

AUI PORT Serial Port RJ-45 RJ-45 RJ-45

RJ-45

Powercord

BRI PORT (RJ-45)

USED TO CONNECT THE ISDN SWITCH

ETHERNET PORT (RJ-45)

USED TO CONNECT THE SWITCHOR PC’S

CONSOLE PORT (RJ-45)

USED TO CONNECT THE ROUTER TO PC’S COM PORT

ATTACHMENT UNIT INTERFACE63-PINS.

TRANSCEIVER

USED TO CONVERT SERIAL PORT TO RJ-45 TO CONNECT SWITCH OR PC’S

63-PINS USED TO CONNECT THE ROUTERS BACK -BACK

ON/OFF SWITCH

RJ-45

AUXILLIARY PORT

Router booting sequenceRouter booting sequenceInternal diagram of router.

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 SpecificsRAM Specifics

RAMCommandExecutive

InternetworkOperating

System(IOS)

ProgramsActiveConfig

FileTables Buffers

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

RAM SpecificsRAM Specifics

RAMPrograms

RAM SpecificsRAM Specifics

RAMInternetwork

OperatingSystem(IOS)

Programs

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

RAM SpecificsRAM 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 SpecificsRAM 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 SpecificsRAM Specifics

RAMCommandExecutive

InternetworkOperating

System(IOS)

ProgramsActiveConfig

FileTables

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

RAM SpecificsRAM 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 ModesRouter Modes

Router modes of Router modes of operationoperation

ROUTER BOOT UP PROCESSSETUP MODE PROMTED DIALOG

BOX TO ENTER THE CONFIGURATION

USER MODEENABLES USER TO LOGIN

ROUTER>

PRIVILEDGE MODE TESTING & TROUBLESHOOTING OF

ROUTER & REMOTE ACCESS.ROUTER#

GLOBAL CONFIGURATION MODEMAJOR COMMANDS RUN FROM HERE

ROUTER(CONFIG)#

Verification of router Verification of router components.components.

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 DefinedShow 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 DefinedShow Commands Definedshow 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