Routers - Basics 1

Differences between Routers and Switches:
1. IP configurations is different
2. Setup questions are different
3. Routers have an AUX port, which Switches dont

Router Interfaces:
1. Ethernet
2. Serial

Important commands:

show interface ---- shows everything, all interfaces and their properties

show ip interface brief ---- brief status of all interfaces

R2#show ip interface brief
Interface                  IP-Address      OK? Method Status                Prot                ocol
FastEthernet0/0           YES NVRAM  up                    down               
Serial0/0                    YES NVRAM  up                    up                 
FastEthernet0/1       unassigned      YES NVRAM  up                    up                 
Serial0/1                  unassigned      YES NVRAM  down              down               
Loopback0         YES NVRAM  up                    up

Interface Status:
There are two status' for any interface -

1. Line
2. Protocol

These can only be UP or DOWN. There are 4 combinations for these 2 status' to be in:
1. Administratively down, down ---- means the interface is in shutdown mode
2. down, down ---- means the interface is DOWN physically even when it is in no shutdown mode
3. up, down ---- means the interface is ok physically (line is up) but there's a problem at data-link (protocol) level
4. up, up ---- no problems :) router is up and running

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