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Configuring Broadcast using IGRP

To broadcast the network 10.1.1.0/24 using IGRP would you use?

A. RouterA(config-router)#network 10.0.0.0

B. RouterA(config-router)#network 10.1.1.0

How does the router handle the subnets under IGRP? I am getting two

answers and none seem to be able to back them up.

1 ACCEPTED SOLUTION

Accepted Solutions

Re: Configuring Broadcast using IGRP

IGRP is classful protocol. SO you need to enter only the first command. THe second command would be accepted by the router, but when you see the running config, the network 10.1.1.0 statement would appear as "network 10.0.0.0".

Conclusion, is that, you need only classful network statements to enable IGRP on an interface. Once network 10.0.0.0 is given under igrp, all interface which has an ip address configured under the 10 network (any subnet) will be enabled with IGRP. ALso it will advertise those networks. IGRP doesnt advertise subnets of a classful network. It autosummarizes at the network boundary and senda 10.0.0.0/8 route to its neighbours.

2 REPLIES

Re: Configuring Broadcast using IGRP

IGRP is classful protocol. SO you need to enter only the first command. THe second command would be accepted by the router, but when you see the running config, the network 10.1.1.0 statement would appear as "network 10.0.0.0".

Conclusion, is that, you need only classful network statements to enable IGRP on an interface. Once network 10.0.0.0 is given under igrp, all interface which has an ip address configured under the 10 network (any subnet) will be enabled with IGRP. ALso it will advertise those networks. IGRP doesnt advertise subnets of a classful network. It autosummarizes at the network boundary and senda 10.0.0.0/8 route to its neighbours.

New Member

Re: Configuring Broadcast using IGRP

Thank you. I was stuck. I could not understand how routing would take place if you have more that one interface attached that used a subnet of 10.0.0.0

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