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Webcast-Catalyst9k
New Member

RIP Question

Can you help me grasp the concept behind the network command. I know the command does 3 things:

broadcast the routing updates out an interface

listens for incoming updates on the same interface

advertise the subnet(s) off that interface in the routing update.

However, when you enter the router subcommand configuration mode and type "network" followed by the network number this is where I get stumped. Is this just the subnet number? If not why? What's the difference between the network number and subnet number?

Example: You have a router with 2 serial interfaces (S0 and S1), 2 Ethernet interfaces (E0 and E1), 1 Token Ring interface (T0). You want to configure the RIP routing protocol. IP Addresses are as follow:

E0 - 10.1.2.3 255.255.255.0

E1 - 172.16.1.1 255.255.255.0

T0 - 10.1.3.3 255.255.255.0

S0 - 199.1.1.1 255.255.255.0

S1 - 199.1.2.1 255.255.255.0

1 REPLY
Bronze

Re: RIP Question

Hi there,

The network statement when used with RIP merely tells the router which interfaces should participate in the route distribution.

As RIP, when initially designed was a classful protocol, the router will accept subnets of classful addresses, but will rewrite the subnets to the classful network address in the configuration.

eg, router1(config-router)# network 10.20.20.0

will be seen in the configuration as

router1(config-router)# network 10.0.0.0

and will mean that ALL interfaces that fall within that class A network address will participate in route distribution.

So for your example, the following will get it working with RIP V1

router(config)#router rip

!! 10.0.0.0 class A address!!

router(config-router)#network 10.0.0.0

!! 172.16.0.0 class B address!!

router(config-router)#network 172.16.0.0

!! 199.1.1.0 class C address!!

router(config-router)#network 199.1.1.0

!! 199.1.2.0 class C address!!

router(config-router)#network 199.1.2.0

I hope that answers your question Mate! Just Bear in mind that if you don't want an interface to participate but you need the network statement there for another interface, then you can use the passive-interface command to tell the router not to use that interface.

Regards,

Brad

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