1. Chapter 5 Managing a Cisco Internetwork

2. Cisco Router Components
Component Description
Bootstrap Stored in the microcode of the ROM, the bootstrap is used to bring a router up during initialization. It will boot the router and then load the IOS.
POST (power-on self-test) Stored in the microcode of the ROM, the POST is used to check the basic functionality of the router hardware and determines which interfaces are present.
ROM monitor Stored in the microcode of the ROM, the ROM monitor is used
for manufacturing, testing, and troubleshooting.
Mini-IOS Called the RXBOOT or bootloader by Cisco, the mini-IOS is a small IOS in ROM that can be used to bring up an interface and load a Cisco IOS into flash memory. The mini-IOS can also perform a few other maintenance operations.
RAM (random Used to hold packet buffers, ARP cache, routing tables, and access memory) also the software and data structures that allow the router to function.
Running-config is stored in RAM, and most routers expand the IOS from flash into RAM upon boot.

3. Cisco Router Components
Component Description
ROM (read-only memory) Used to start and maintain the router. Holds the POST and the bootstrap program, as well as the mini-IOS.
Flash memory Stores the Cisco IOS by default. Flash memory is not erased when the router is reloaded. It is EEPROM (electronically erasable programmable read-only memory) created by Intel.
NVRAM (nonvolatile RAM) Used to hold the router and switch configuration. NVRAM is not erased when the router or switch is reloaded. Does not store an IOS. The configuration register is stored in NVRAM.
Configuration register Used to control how the router boots up. This value can be found as the last line of the show version command output and by default is set to 0x2102, which tells the router to load the IOS from flash memory as well as load the configuration from NVRAM.

4. Viewing/Configuring Configuration Register
Router#sh ver
Router#config t
Router(config)#config-register 0x2142
Router(config)#do sh ver

5. Recovering Password
1. Boot the router and interrupt the boot sequence by performing a break, which will take the router into ROM monitor mode. (Ctrl + Break)
2. Change the configuration register to turn on bit 6 (with the value 0x2142).
Series 2600:
rommon>confreg 0x2142
Series 2500:
>o/r 0x2142
3. Reload the router.
rommon>reset
>i
4. Do not enter Setup Mode Dialog.

6. 5. Enter privileged mode.
6. Copy the startup-config file to running-config.
Router#copy start run
7. Change the password.
Router#config t
Router(config)#enable secret new password
Router(config)#enable password new password
8. Reset the configuration register to the default value.
Router(config)#config-register 0x2102
9. Save the router configuration.
Router(config)#^Z
Router#copy run start
10. Reload the router (optional).
Router#reload

7. Boot System Commands
Router(config)#boot system flash c2800nm-advsecurityk9-mz bin
Router(config)#boot system tftp c2800nm-advsecurityk9-mz bin
Router(config)#boot system rom
Router(config)#do show run | include boot system
boot system flash c2800nm-advsecurityk9-mz bin
boot system tftp c2800nm-advsecurityk9-mz bin
boot system rom
Router(config)#

8. Backing Up and Restoring the Cisco IOS
Router#ping ip of tftp server
Router#sh ver
Router#sh flash
Router#sh run
Router#sh start
To Backup IOS
Router#copy flash tftp
To Restore or Upgrade IOS
Router#copy tftp flash
To Backup Configuration
Router#copy run tftp
Router#copy start tftp
To Restore Configuration
Router#copy tftp run
Router#copy tftp start

9. Cisco Discovery Protocol (CDP)
Router#sh cdp
Global CDP information:
Sending CDP packets every 60 seconds
Sending a holdtime value of 180 seconds
Sending CDPv2 advertisements is enabled
Router(config)#cdp ?
advertise-v2 CDP sends version-2 advertisements
holdtime Specify the holdtime (in sec) to be sent in packets
log Log messages generated by CDP
run Enable CDP
source-interface Insert the interface’s IP in all CDP packets
timer Specify rate (in sec) at which CDP packets are sent run
Router(config)#cdp timer 60
Router(config)#cdp holdtime 180

10. Router#sh cdp neighbors
Router#sh cdp neighbors detail
Router#sh cdp entry *
Router#show cdp entry * protocols
Router#show cdp entry * version
Router#sh cdp traffic
Router#sh cdp interface
Router#config t
Router(config)#int s0/0/0
Router(config-if)#no cdp enable

11. Using Telnet Router#telnet 192.168.40.1 OR Router#192.168.40.1
To open more Telnet sessions
R40.1#{Ctrl+Shift+6 then x}
Router#telnet
To view sessions from your Router to the others
Rouetr#sh sessions
To view sessions from the others to your Router
Rouetr#sh users
To end session
From your Router to others (on remote Router)
R40.1#exit
From your Router to others (on local Router) Router#disconnect no. of session
From others to your Router (on local Router) Router#clear line no. of session

12. Resolving Names Router(config)#ip name-server ip of DNS Server
1. Local host file on Cisco Router
Router(config)#ip host host_name ip
Router(config)#exit
Router#sh hosts
2. Using DNS
Router(config)#ip domain-lookup
Router(config)#ip name-server ip of DNS Server
Router(config)#ip domain-name Domain_Name.com

13. Debugging Checking Connection Router#debug all Router#undebug all
Router#no debug all
Router#sh processes
Router#sh processes cpu
Checking Connection
Router#ping ip
Router#traceroute ip