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Issue on MPLS

I am a customer who has the following set up:

37501-----CE1----PE1-MPLS-PE2-----CE2---37502

A GRE tunnel runs from 37501 to 37502.

The problem I'm having is that I have a primary and backup link from CE1-PE1, and when it failsover to the backup link OSPF hellos are no longer recieved from 37502 to 37501, and the ajacency is stuck in INIT (on 37502; on 37501 it is removed).

The tunnel is still up and pings work from both ends. On CE1 all entries in the routing table switch to the new interface (a mixture of OSPF and static routes run between CE-PE).

Any ideas what the problem could be? I know nothing about routing within MPLSs; could there be an issue within it?

Any help much appreciated,

Thanks,

J

2 REPLIES
New Member

Re: Issue on MPLS

Is there a router id that is associated with the ospf neighbors ? And if so , we may have to check the routing for that router id in the PE whether on static or OSPF.

Also please tell how the ospf is running, whether between the PE and CE or between the CE directly.

MPLS does not contribute much for the routing, jus the presence of the label for a prefix trying to be reached by a CE is sufficient.

So may be a diagramatic representation with sample prefixes and protocols run will help.

Ramya

New Member

Re: Issue on MPLS

Hi Ramya, many thanks for your response.

It's slightly complicated in that OSPF runs across the MPLS and ends at each CE, and then OSPF runs across the tunnel, so they're completely separate (this is just an interim measure). Therefore in the CE routing tables there are OSPF entries for the MPLS network and connected routes to the 3750. There's no static redistribution into OSPF. On the 3750s there are OSPF routes from our networks only.

On CE1 usually both backup and primary links have p-2-p adjacencies with PEs, when the primary goes down, the secondary's routes are placed into the routing table, including the default route (which is a floating static pointing to the PE) and there is no entries pointing to the primary interface.

Does this answer your questions?

Thank you.

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