Ali Caliskan

Administrative Distance (AD)

Before starting RIP we should about Administrative Distance (AD).
AD: Sets the priority of routing protocols. If 2 protocols are configured on a router, the router will first put the data of the low AD protocol in the routing table.
The table below contains the administrative distance values of the routing protocols. The data of the protocol with a low AD value is placed first in the routing table.

DEFAULT ROUTİNG

Default routing is used to send packets to the next-hop router for an unknown remote destination network that is not in the routing table. Default routing should only be used in stub networks, which are the only way out of the network.

As you can see in the above picture, while R1 and R3 can be used defective routing. Because R2 is not effective to use the default routing.
Router(config) #ip route 0.0.0.0 0.0.0.0 10.0.0.1
The above command means to send all unknown packets to output 10.0.0.1, wherever they come from.

IP ROUTING

Routers know how to reach the networks they are connected to. However, they do not know how to reach remote networks that not connected. But, they can learn how to access remote networks to which they are not connected by using one of the following routing protocols.
1. Static routing
2. Default routing
3. Dynamic routing
a) RIP (international standard)
1) RIPv1       2) RIPv2
b) IGRP (cisco-based protocol, but not supported by cisco anymore)
c) EIGRP (cisco-based)
d) OSPF (international standard)
e) Is-Is  (international standard)

There are 4 rules to assign IP addresses to the routers.

1. All the interfaces of routers should be in a different network (subnet).
2. Both interfaces of routers facing each other should be in the same network (subnet).
3. LAN  that under the router interface should be n the same network (subnet).
4. All the LAN and WAN networks must be in a different network (subnet)

Configure interfaces of routers should be in the interface mode which under the global configuration mode.

I want to show you in this article basic routing configuration. But before this ı must explain the mod of routing. Now let starting.

There are 3 main modes of routing.  U ser mode, privileged mode, global configuration mode. there are some more modes but all of them are under the global configuration mode.

route> This mode is named user mode. Provides only some basic monitoring commands such as; show version, show flash, show IP interface brief and ping, traceroute.  modifications and configuration are not allowed in this mode.