Router Components

Router ComponentsBack panel of routerRouter Booting Sequence.Router Modes of operation.Table of Contents

ROUTER BACKPANEL AUI PORTSerial PortRJ-45RJ-45RJ-45RJ-45PowercordBRI PORT (RJ-45) USED TO CONNECT THE ISDN SWITCH ETHERNET PORT (RJ-45)USED TO CONNECT THE SWITCHOR PCSCONSOLE PORT (RJ-45) USED TO CONNECT THE ROUTER TO PCS COM PORT

ATTACHMENT UNIT INTERFACE63-PINS.TRANSCEIVERUSED TO CONVERT SERIAL PORT TO RJ-45 TO CONNECT SWITCH OR PCS63-PINS USED TO CONNECT THE ROUTERS BACK -BACK ON/OFF SWITCHRJ-45 AUXILLIARY PORT

Router booting sequenceInternal diagram of router.

As the router is booted, the following is loaded into RAMs Working Storage.RAM SpecificsRAMCommandExecutiveInternetworkOperatingSystem(IOS)ProgramsActiveConfigFileTablesBuffers

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

RAM SpecificsInternetworkOperatingSystem(IOS)ProgramsOnce the IOS is located by the bootstrap program, it is loaded in to RAM.

RAM SpecificsCommandExecutiveInternetworkOperatingSystem(IOS)ProgramsPart 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 SpecificsCommandExecutiveInternetworkOperatingSystem(IOS)ProgramsActiveConfigFileOnce 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 SpecificsCommandExecutiveInternetworkOperatingSystem(IOS)ProgramsActiveConfigFileTablesThe tables are loaded from the configuration file including... ARP Tables Routing Tables

RAM SpecificsCommandExecutiveInternetworkOperatingSystem(IOS)ProgramsActiveConfigFileTablesBuffersFinally, all leftover memory in RAM is used as the buffer for processing incoming and outgoing packets.

Router Modes

Router modes of operationROUTER BOOT UP PROCESSSETUP MODE PROMTED DIALOGBOX TO ENTER THE CONFIGURATION USER MODEENABLES USER TO LOGINROUTER>PRIVILEDGE MODE TESTING & TROUBLESHOOTING OF ROUTER & REMOTE ACCESS.ROUTER#GLOBAL CONFIGURATION MODEMAJOR COMMANDS RUN FROM HEREROUTER(CONFIG)#

Verification of router components.

FlashNVRAMRAMInternetwork Operating SystemProgramsActiveConfigurationFileTablesandBuffersBackupConfigurationFileOperatingSystemsInterfaces

Show Commands Definedshow 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 fileshow 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 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