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New Member

OSPF stuck in EXCHANGE

If OSPF is stuck in EXCHANGE that would mean that the link state databases aren't adjacent right?

I have a strange problem where OSPF isn't getting past that point. I've checked the MTU, MSS, authentication, networks, filtering etc. on both sides. I've even reduced the config to the bare minimum on the CPE and it's not working.

On the PE the config is shared and working with others. There are other CPE's with the same config and working.

If I look at the OSPF database on the CE and PE I can see the routes there but not getting to the point where they get installed into the routing table.

I'm missing something here and I'm not sure what?

3 REPLIES
Silver

Re: OSPF stuck in EXCHANGE

This usually happens when there is an MTU mismatch but you mention that you have already checked this. Have you tried running any debugs like 'debug ip ospf adj'? Is this between two Cisco devices or a Cisco device and another vendor's router?

New Member

Re: OSPF stuck in EXCHANGE

I resolved the issue yesterday. I made sure the MTU on both routers was the same but the DSLAM in the middle doesn't support fragmentation and is being used as a LAC. I dropped the MTU to 1448 on both sides and it's now working like a charm.

Silver

Re: OSPF stuck in EXCHANGE

I hope there are filters in any routers to block any subnets.

Thanks.

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