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 Post subject: OSPF selective neighbors
PostPosted: Mon Apr 04, 2005 11:01 am 
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Any suggestions on how to limit the neigbors on an Ethernet OSPF session? I have a router that I not only want to act as DR, but I want all other routers on that Ethernet to connect to it and it alone...not each other.

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PostPosted: Mon Apr 04, 2005 11:16 am 
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There are a few ways to go about doing this.

Cant remember off the top of my head 100% on this for a broadcast network type. However set all the other Routers OSPF to priority 0 is one possible way. I will have to check this one out later to be sure.

Another would be to set up an access list to accept 224.0.0.6 sourced from DR router only.

Also you could go about using a non broadcast network type and staticly setting the DR router with priority under the OSPF config. This would be quite a bit of admin overhead.


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PostPosted: Mon Apr 04, 2005 11:17 am 
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Well ... I'm sure you know to set the priority up on the desired DR router and then cycle the OSPF processes. That will get your DR elected.

May I ask why you don't want neighbor relationships with the other routers on the segment?

mr

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PostPosted: Mon Apr 04, 2005 11:19 am 
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rizacerx wrote:

Another would be to set up an access list to accept 224.0.0.6 sourced from DR router only.

DP


This would work ... but wouldn't it chew up CPU utilization?

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PostPosted: Mon Apr 04, 2005 11:24 am 
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markrohlf wrote:
rizacerx wrote:

Another would be to set up an access list to accept 224.0.0.6 sourced from DR router only.

DP


This would work ... but wouldn't it chew up CPU utilization?



All depends on what the router is and what the router is doing.


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PostPosted: Mon Apr 04, 2005 5:24 pm 
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I'm sure you have your reasons for doing thins, but you're killing the redundancy by doing it you realize? If your DR fails and things move to the BDR the other rouers on the segment aren't going to be able to talk to it.

My $0.02


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PostPosted: Tue Apr 05, 2005 9:52 am 
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It's a hard scenario to explain...it's Ethernet over wireless and each OSPF neighbor except the DR should act like a stub. We can't use static routes because the Ethernet of the customer router does not go down when the wireless link goes down.

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PostPosted: Tue Apr 05, 2005 10:40 am 
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is this in a multi-vendor environment?

I just wonder if EIGRP might provide more efficient use of bandwidth.

mr

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PostPosted: Wed Apr 06, 2005 9:51 pm 
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A thought....

Now this isn't the cleanest way, or most efficient approach to this issue, but if your DR has some resources to spare, then this could be a solution.

Run seperate OSPF processes for each neighbour, and the redistribute as needed :D

Yeh, I know, ugly ugly ugly. It would work though :P


Steve wrote:
It's a hard scenario to explain...it's Ethernet over wireless and each OSPF neighbor except the DR should act like a stub. We can't use static routes because the Ethernet of the customer router does not go down when the wireless link goes down.


Then do just that... Make them stub areas. Grantd your gonna chew up a couple of subnets... And from the sounds of things you'll have to use subinterfaces on a single ethernet interface... But I can't thin of any reason wy it shouldn't work.

Again I don't think this is a very clean way of doing things, but it could be hacked together to work.


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