Internet Control Message Protocol (ICMP)

• It is used to send error & control information between ip network devices.
• There are many diffident messages that can be shared, including the following: 

1. Echo request: Determines whether on ip node ( a host or a router is available on network.)
2. Echo Reply: Replies to ICMP echo request.
3. Destination Unreachable: Informs the host that a datagram can't be delivered.
4. Source Quench: Informs the host to lower the rate at which it sends datagram because of congestion.

5. Redirect: Informs the host of a preferred rate.

6. Time Exceeded: Indicate that the TTL of IP datagram has expired.

Using the Pipe

 It is the output modifier. This pipe ( | ) allow us to wade through all the configurations or other long out puts & get straight to our goods fast.

Arman#sh run | ?
Append Append redirected out put to URL ( URLs supporting append operation only )
Begin Begin with the line that matches.

Do command

** Beginning with IOS version 12.3

• Cisco has finally added a command to the IOS that always you to view the configuration & statics from within configuration mode.

 ** In fact with a pre -12.3 router,

• you'd get the following error if you tried to view the configuration from global - Config

you see:

Router (config)# sh run

             ^

% invalid input detected at  ' ^ '  marker

• Compare that to the output i got from entering that same command on my router that's running the 12.4 IOS

Enter configuration commands, one per line. End with CNTL/Z

Router Interface Configuration

* IP addresses  *Media Type  * Bandwidth  * Other administrative commands

Cisco 2522

• Cisco 2522 has 10 serial:  

Router (config)# int Serial?

<0-9> serial interface number

The 2522 router has one Ethernet 10baset port; Router (config)# int ethernet ?

<0-0> Ethernet interface number

Router (config)# int ethernet 0

Router (config-if)#

the Router

Connecting to the Router

We have three ways:

1. Auxiliary Port / Phone line 
2. Console Port / Rj-45 / Console Cable or Console cable-rollover
3. Telnet /  (USER MODE) ip net - 10Baset t

Cisco Router Components 

1. Bootstrap: boot the router & then load the IOS.    [Microcode of the Rom]
2. POST (Power On Self Test): check the basic functionality of the router hard ware.    [Microcode of the Rom]
3. Rom monitor: testing & troubleshooting.    [Microcode of the Rom]
4. Mini-IOS (Rx-boot / boot-loader): small IOS in Rom. load a Cisco IOS into flash memory.
5. RAM:  hold packet buffers, ARP cache, routing table.
6. ROM: star & main tent the router.
7. Flash memory: hold the Cisco IOS, NOT erased when the routers is reloaded, it is EEPROM.
8. NVRAM: hold the router & switch configuration.

Cisco Router 

Summary:

• Basic IOS: ROM
• Boot strap: ROM
• Diagnestics: ROM
• Current IOS: Flash
• Start up configuration: NVRAM
• Running configuration: RAM