1.3 Basic Router

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Router on basic

Basic Router

IPMACNetworking Academy

ObjectivesObjectives

Hardware and software components of the routersOperation of the routers when it boots upDifferent ways to access and configure the routersFunction and operation of IOSEstablishing session and log into routerCLI help features


Router BasicRouter Basic


Router Basic Router Basic –– ROM & FlashROM & Flash

ROMContains bootstrap program for power-on diagnosticsSubset of operating system softwareSoftware upgrades in ROM require replacing pluggable chips on the CPU

FlashErasable, re-programmable ROM Holds the operating system imageAllows you to update software without removing and replacing chips on the processorcontent remains when you power down or restartmultiple versions of IOS software can be stored in Flash memory


Router Basic Router Basic –– RAM/DRAMRAM/DRAM

RAM/DRAMStores

Router’s active configurationrouting tablesARP cachefast-switching cachepacket buffering (shared RAM)packet hold queues

Content is lost when power down or restartNVRAM

Nonvolatile RAMStores

router’s backup/startup configuration fileContent remains when you power down or restart


Router Basic Router Basic -- InterfacesInterfaces

Network connection through which packets enter and exit a routerCan be built-in on motherboard: Fixed Card

or Separate interface module: Module Card


RouterRouter’’s interfacess interfaces

Console port:Configure the router by terminal (RJ-45).

Auxiliary port:Configure the router via modem (RJ-45).

LAN ports:LAN interfaces.

WAN ports:WAN interfaces.


LAN interfaces:LAN interfaces: AUI and RJAUI and RJ--45 / DB45 / DB--9/ MIC, SC 9/ MIC, SC and STand ST


WAN interfacesWAN interfaces

Synch/Asynch:Serial DB-60, …

Asynchronous: DB-68 with octal cable, RJ-45.

T1, E1: DB-15, RJ-45 with CSU/DSU built-in.

ISDN: BRI: RJ-45 , PRI: same as T1, E1 interface.

POTS:RJ-45 with Modem build-in.


WAN interfaces: Synch/AsynchWAN interfaces: Synch/Asynch


WAN interfaces: AsynchWAN interfaces: Asynch


Router StartupRouter Startup

Initialize and check hardware

Initialize and check hardware

Finds and loads IOS

Finds and loads IOS

Finds and loads configuration

Finds and loads configuration


Startup sequenceStartup sequence


Managing Configuration FilesManaging Configuration Files

IOS on a router uses a configuration file for the initial configuration at router startup and the active, running configuration file.The startup configuration file is in NVRAM.The running configuration file, which is in RAM, is used during operation.When the router first comes up, the router copies the stored configuration file from NVRAM into RAM.To display the content the configuration files, you use the show command.


Common Common ConfigConfig. register values. register values

0 0 1 0 0 0 0 1 0 0 0 0 0 0 0 00x

0x2100 : System bootstrap prompt

0 0 1 0 0 0 0 1 0 0 0 0 0 0 0 10x

0x2101 : Boot system from ROM

0 0 1 0 0 0 0 1 0 0 0 0 0 0 1 00x

0x2102 : Boot system from flash


Reasons to modify configuration Reg.

Recovering a lost passwordChanging the console baud rateEnabling or disabling BreakForcing the router to boot automatically from the system bootstrap software OR from its system image in Flash memory, OR to read any boot system commands that are stored in the configuration file in NVRAM.

Router(config)# config-register 0x2102Router(config)# exitRouter# show version


show versionshow versionCisco Internetwork Operating System Software IOS (tm) C2600 Software (C2600-J1S3-M), Version 12.2(15)T14, RELEASE SOFTWARE (fc4)Technical Support: http://www.cisco.com/techsupportCopyright (c) 1986-2004 by cisco Systems, Inc.Compiled Sat 28-Aug-04 06:47 by cmongImage text-base: 0x80008098, data-base: 0x819608A4ROM: System Bootstrap, Version 11.3(2)XA4, RELEASE SOFTWARE (fc1)ROM: C2600 Software (C2600-J1S3-M), Version 12.2(15)T14, RELEASE SOFTWARE (fc4)IPMAC-2600 uptime is 11 minutesSystem returned to ROM by power-onSystem image file is "flash:c2600-j1s3-mz.122-15.T14.bin"cisco 2610 (MPC860) processor (revision 0x203) with 61440K/4096K bytes of memory.Processor board ID JAD05030HG4 (3143568490)M860 processor: part number 0, mask 49Bridging software.1 Ethernet/IEEE 802.3 interface(s)1 Serial network interface(s)32K bytes of non-volatile configuration memory.16384K bytes of processor board System flash (Read/Write)

Configuration register is 0x2102


CommandCommand--Line InterfaceLine Interface

Cisco routers run Cisco IOS Software.IOS supplies several features:

Basic connectivity for a variety of protocols.Security features for those protocols.Reliable and scalable network services.

This chapter focusses in three main features of Cisco IOS Software:

Cisco IOS Software command-line interface (CLI)How to configure a routerHow to upgrade Cisco IOS Software in a router, and what happens during the boot process.


Establishing a HyperTerminal sessionEstablishing a HyperTerminal session

Rollover cable

Console port

Com1 or Com2 serial port

Terminal or a PC with terminal emulation software

Router

To access the CLI, use one of three methods.The cable from the console to a PC requires a rollover cable.The console port is intended for local administrative access.


Establishing a HyperTerminal sessionEstablishing a HyperTerminal session

Important: A console connection is not the same as a network connection!

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Access to the CLIAccess to the CLI

The console port is intended for local administrative access.Aux is intended for remote administrative accessRouter / Switch can be accessed via remote telnet


Initial Configuration (Setup Mode)Initial Configuration (Setup Mode)

Setup mode leads a router administrator to a basic router configuration by using questions that prompt the administrator for basic configuration parameters.Setup mode is used most frequently when the router boots, and it has no configuration in NVRAM.Setup mode can be entered by using the setup command from privileged mode.


Setup ModeSetup Mode

Most networking personnel do not use setup at all, but new users sometimes like to use setup mode.You can abort the setup process before answering all the questions by pressing CTRL+C.


User ModeUser Mode

From any of the three methods of accessing the router, you enter user exec mode.User exec mode, also called user mode, enables you to look around but not break anything.

Passwords are required for Telnet access, but there are no preconfigured passwords.


CLI Password ConfigurationCLI Password Configuration

The login command tells the router to display a password prompt.The password command specify the text password to be typed by the user to gain access.Several concurrent Telnet connections to a router are allowed.


Privileged ModePrivileged Mode

The privileged mode allows user to execute the commands.The enable command is used to reach this mode, so it is also called enable mode.


User and Privileged ModesUser and Privileged Modes

Enable command: from user-mode to privileged-mode.

Disable command: from privileged-mode to user-mode.


Password for enable modePassword for enable mode

A password can be used to prevent the users move from user-mode to enable-mode (privileged-mode).The password set with enable password command can be seen in configuration files.The password set with enable secret command is encrypted and cannot be decrypted.If both are configured, the password is set by the enable secret command is used.

Not recommended, clear text

Use this command instead, password is md5 encryped


Configuring Cisco IOS SoftwareConfiguring Cisco IOS Software

Be careful when you type in a configuration command!The changes to the configuration occur immediately each time you press

the Enter key at the end of a command.


Keyboard help in the router CLIKeyboard help in the router CLI


Troubleshooting command line errorsTroubleshooting command line errors


Router(config)#hostname GatewayGateway(config)#Gateway(config)#banner motd #Enter TEXT message. End with the character '#'.Warning!Stay away! #Gateway(config)#endGateway#exitPress RETURN to get started.

Warning!Stay away!

MOTD (Message Of The Day)

Prompt changes

Hostname & messageHostname & message--ofof--thethe--day (MOTD)day (MOTD)


Configuring interface descriptionConfiguring interface description


Configuring a serial interfaceConfiguring a serial interface


show show ipip interface interface commandcommand

A serial interface will not show “up” and “up” unless both ends are properly configured (mostly) and a the no shutdown command is used. If one router’s configuration looks okay, check the other router’s configuration.

Router# show ip interface brief

Interface IP-Address OK? Method Status ProtocolEthernet0 131.108.1.11 YES manual up up Serial0 198.135.2.49 YES manual administratively down down

What is wrong here? The administrator has either done a “shutdown” on the interface or has forgotten to do a “no shutdown”.


Lab

Real world

On serial links that are directly interconnected, as in a lab environment, one side must be considered a DCE and provide a clocking signal.The clock is enabled and speed is specified with the clock ratecommand.Router(config)#interface serial 0/0Router(config-if)#clock rate 56000Router(config-if)#no shutdown



How can you tell which end is the DTE and which end is the DCE?Look at the label on the cable.Look at the connecter between the two cables - The DTE cable will always be male and the DCE cable will always be female.

DTE Cable DCE Cable



RouterA#show controllers serial 0HD unit 0, idb = 0xECA4C, driver structure at 0xF1EC8buffer size 1524 HD unit 0, V.35 DTE cablecpb = 0x62, eda = 0x403C, cda = 0x4050RX ring with 16 entries at 0x62400000 bd_ptr=0x4000 pak=0x0F5704 ds=0x62FFB8 status=80 pak_size=22

RouterB#show controllers serial 0buffer size 1524 HD unit 0, V.35 DCE cable, clockrate 64000cpb = 0x62, eda = 0x408C, cda = 0x40A0RX ring with 16 entries at 0x62400000 bd_ptr=0x4000 pak=0x0F2F04 ds=0x627908 status=80 pak_size=22

RouterBDCE cable

RouterADTE cable

This is one of few commands where there must be a space between the interface type and the port.



RouterB(config)#inter serial 1RouterB(config-if)#clock rate ?Speed (bits per second)120024004800960019200384005600064000…………………<text omitted>20000004000000<300-4000000> Choose clockrate from list above

RouterB(config-if)#clock rate 64000RouterB(config-if)#

RouterBDCE cable

RouterADTE cable



Host name resolutionHost name resolution

Router# ping 172.16.32.1Router# ping Auckland

Router# telnet 192.168.53.1Router# telnet Beirut

Router# traceroute 192.168.89.1Router# traceroute Capetown


Configuring host tablesConfiguring host tables


IpIp domaindomain--lookuplookup

Router(config)# ip domain-lookupRouter#wrehTranslating "wreh"...domain server (255.255.255.255) (Takes a few seconds)Translating "wreh"...domain server (255.255.255.255) (Takes a few seconds)

Router(config)# no ip domain-lookupRouter#wrehTranslating "wreh"% Unknown command or computer name, or unable to find computer address


Viewing the Configuration FilesViewing the Configuration Files

show running-config: To display the currently used, active, running configuration file.show startup-config: to display the stored, startup configuration file.


The The copycopy commandcommand

The most basic method for moving configuration files in and out of a router is to use the copy command to copy files between RAM and/or NVRAM on a router or/and a TFTP server.The copy command always replaces the existing file when the file is copied into NVRAM or into a TFTP server.When the copy command copies a configuration file into RAM, the configuration file in RAM is not replaced.

It just merges the RAM configuration file and the newly copied files.

If you change the running config and then decide that you want to revert to what’s in the startup-config file, the only way to guarantee that is to issue the reload command.


Moving Configuration FilesMoving Configuration Files


Copy IOS Image into Flash MemoryCopy IOS Image into Flash Memory


Backup IOS to a TFTP ServerBackup IOS to a TFTP Server


What does the IOS name means? *What does the IOS name means? *

It is a good idea to keep the same filename when copying the file into flash.In particular, the first part of the name implies the router hardware platform.The second part identifies the feature set, with individual letters identifying different options – for instance, “j” means the IOS has the Enterprise feature set.Finally, the last few digits tell us some information about the run-time features – for instance, a “z” means that the file is compressed, and need decompression when being loaded.

C2600-j1s3-mz.122-15.T14.bin

* See www.cisco.com/warp/customer/620/4.html#image for more information


SummarySummary

Purpose and operation of IOSIOS naming conventionCLI: use EXEC and privileged EXEC modeCLI help and editing commandRouter name, description, banner, hosts..Router show commandsBackup configuration filesShow version


Prepare for the labPrepare for the lab

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1.3 Basic Router