CCNA Study MaterialCisco Router Basics The Router Router Components (internal) Router Components (external) Router's Startup Procedure Configuration Register Cisco CLI Command Modes ser !xec Mode Pri"ileged !xec Mode Setup Mode R#M Monitor ModeTheRouter:-$Router isala%er &net'or(de"icethat mo"esdata)et'eendifferent net'or(segmentsandcanloo(intoapac(et headertodeterminethe)est pathforthepac(et totra"el*Routers can connect net'or( segments that use different protocols* The% also allo' allusers in anet'or(toshareasingleconnectiontotheInternet or a+$,* It isusedtoimpro"enet'or(performance )%-./ segmenting the net'or( and creating separate collision 0 )roadcast domains*/ reducing competition for )and'idth*/ 1roadcasts are not for'arded to other net'or( segments*/ Increases securit% )% using $ccess Lists*Router Components (internal) ROM :-R#M is used to store the router's )ootstrap startup program2 operating s%stem soft'are2and po'er.on diagnostic tests programs* In order to perform R#M upgrades %ou remo"e and replaceplugga)le chips on the mother)oard* Flash Memory :- It holds operating s%stem image(s)* 3lash memor% is erasa)le2 reprogramma)leR#M* 4ou can perform Cisco I#S soft'are upgrades 'ithout ha"ing to remo"e and replace chips*3lash content is retained 'hen %ou s'itch off or restart the router* RAM:-R$M is used to store operationalinformation such as routing ta)les2 router's runningconfiguration file* R$M also pro"ides caching and pac(et )uffering capa)ilities* Its contents are lost'hen %ou s'itch off or restart the router* NVRAM :- ,5R$M (non"olatile R$M)2 is used to store the router's startup configuration file* It doesnot losedata'henpo'er iss'itchedoff* Sothecontentsof thestartupconfigurationfilearemaintained e"en 'hen %ou s'itch off or restart the router* Netor!"nter#aces:-Therouter's net'or( interfaces arelocatedonthemother)oardor onseparate interface modules* 4ou configure !thernet or To(en Ring interfaces to allo' connection to aL$,* The s%nchronous serialinterfaces are configured to allo' connection to +$,s* 4ou can alsoconfigure IS6, 1RI interfaces to allo' connection to an IS6, +$,**http://www.mcmcse.com/CCNA Study MaterialRouter Components ($%ternal)$ router can )e configured o"er an% of its net'or( interfaces* 4ou can suppl% configuration informationto a router using-.T3TP ser"ers - Tri"ial 3ile Transfer Protocol7 $ simplified "ersion of 3TP that allo's files to )etransferred from one computer to another o"er a net'or(*"irtual terminalsnet'or( management stationsRouter&s 'tartup (roce)ure!achtime%ous'itchontherouter2it goesthroughpo'er.onself.test diagnosticsto"erif%)asicoperation of the CP2 memor% and net'or( interfaces*The s%stem )ootstrap soft'are in R#M ()oot image) executes and searches for "alid routeroperating s%stem soft'are (Cisco I#S image)* I#S is acron%m for Internet'or( #perating S%stem*There are three places to find the Cisco I#S image to load-/ 3lash memor%/ $ T3TP ser"er on the net'or(/ R#MThe source of the Cisco I#S image is determined from the )oot field setting of the router'sconfiguration register*Con#i*uration Re*istration- $ 89.)it register used to control ho' the router )oots up2 'here the I#Simage2ho' to deal'ith the ,5R$M configuration2setting the console )aud rate and ena)lingordisa)ling the )rea( function*The default setting for the configuration register indicates that the router should attempt toload a Cisco I#S image from flash memor%* If the router finds a "alid I#S image2 it searches for a "alid configuration file* If %our routerdoesnot finda"alids%stemimage2 or if itsconfigurationfileiscorruptedat startup2 andtheconfiguration register ()it 8&) is set to enter R#M monitor mode2 the s%stem 'ill )%pass the ,5R$Msetting and enters R#M monitor mode* This also allo' access to the router in the e"ent a pass'ord islost*The configuration file2 sa"ed in ,5R$M2 is loaded into main memor% and executed one line ata time* These configuration commands start routing processes2 suppl% addresses for interfaces2 andset media characteristics*If no configurationfileexists in,5R$M2 the operatings%stem executesa :uestion.dri"eninitial configuration routine called the s%stem configuration dialog*This special mode is also called the Setup mode*Cisco C+" Comman) Mo)esTheCiscoI#Ssoft'arepro"ides%ou'ithaccesstose"eral different commandmodes*!ach command mode pro"ides a different group of related commands*http://www.mcmcse.com/CCNA Study MaterialThe Cisco Command Line Interface (CLI) is called !;!C* !;!C has t'o modes-./ ser mode/ Pri"ileged mode3or securit% purposes the t'o !;!C modes ser"e as t'o le"els of access to Cisco I#Scommands*!;!C user commands allo' %ou to/ connect to remote de"ices/ ma(e temporar% changes to terminal settings/ perform )asic tests/ list s%stem informationIf %ou'ant toaccesspri"ilegedmode%ouha"etoenter apass'ord* Thecommandsa"aila)le in Pri"ileged mode also include all those a"aila)le in ser mode* 4ou can use Pri"ileged !;!Ccommands to-./ set operating parameters/ perform a detailed examination of the router's status/ test and de)ug router operation/ access glo)al and other included configuration modes3rom Pri"ileged mode %ou can enterglo)alconfiguration mode*This gi"es %ou accesstoconfiguration commands that affect the s%stem as a 'hole2 and to other configuration modes*4ou can specif% the source of the configuration commands as )eing from -./ a terminal / memor% / the net'or(4ou canaccessman%otherspecificconfiguration modesfrom