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Link State Routing Protocol Question

"In LSP, one router in each area is designated as the authoritative source of routing information (called a designated router). Each area router receives updates from the designated router" Why need designated router? How it work? Why can?t it just broadcast LSP and leant the routing information without the need of designated router? Is designate router the same as backbone or root area in OSPF? Is "area" concept only be used in Link State Routing Protocol OSPF?

3 REPLIES
Silver

Re: Link State Routing Protocol Question

The idea of electing a DR is to minimize the amount of information exchange in a particular segment.For more details kindly follow the url given below,

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr_c/ipcprt2/1cfospf.htm

Re: Link State Routing Protocol Question

hi...

you will find area topology in IS IS also...

here we are using the Area as well as DR and BDR for reducing the LSA flooding in the area... each router in ospf area will send update to the DR on multicast address and then DR will send the multicast update to all other router in the area... here each and every router in the area have the full adjucancy with DR but they are not in the full adjucancy with any other router ...

hope this will help you

rate this post if it helps

regards

Devang

Bronze

Re: Link State Routing Protocol Question

Hi.

Mainly OPSF is working on Multicast, this will reduce your flooding of LSA in network. Broadcaste will create problem when you hava more number of router or you can say large network.

So in OSPF only DR is resposible to inform about changes in network to all the routers in his area,

I hope this will solve your problem.

-Minu

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