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New Member

Black Hole Routing Issues

We are currently migrating from Nortel Accelars to Cisco 6513s. We currently route at layer 3 between the two hardware platforms via Gigabit interfaces on both kit. Problem lies when the gigabit interface goes down on the Nortel side but remain up on the Cisco side. It is this situation of the link up on the Cisco 6513 that routes all the traffic into a potential black hole.

Does anybody know why the interface on the cisco 6513 stays up even thou the adjacent interface has gone down.

Any help would be greatly appreciated


Re: Black Hole Routing Issues

Probably because you have only lost one side of the connection and it still thinks it is up on the one side . I don't know if you can use UDLD with the Nortel gear or not but if you can this would solve your problem .

New Member

Re: Black Hole Routing Issues

The nortel swiches do not understand UDLD so can't use this solution.

Any other ideas?

Cisco Employee

Re: Black Hole Routing Issues

Given that UDLD can't be used, you could probably solve the issue by detecting the unidirectional state of the link using a routing protocol such as OSPF. What routing protocol do you currently use?

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
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