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OSPF, neighbors and routes

We have the following MPLS setup with OPSF as the routing protocol:

Provider edge routers (PE) act as ABR?s between the remote customer owned and managed routers (CE) and the Area 0 backbone. So, the Ethernet interface and Serial interface of the CE are on the same Area as well as the Serial Interface of the PE. The PE?s, acting as ABR?s then in turn connect all the remotes to Area 0.

The main site is Area 0 and each remote site is in a different incrementing area. So each remote router has all interfaces in the same area. (site 1 = area 1, site 2 = area2 etc?).

This may have nothing to do with my question:

How does OSPF handle the neighbor relationship and how the routes are processed?

For example, if I am distributing static routes at the main site (area 0) and give it a metric of 1000, the remote site that is Area 1 (adjacent)shows the route as an External route with a metric of 1000.

But the rest of the sites (area 2, area 3 and so on) show the route as an external route with a metric of 66.

The exact metric number I am not concerned about, but why aren?t all sites showing the metric of 1000?


Re: OSPF, neighbors and routes


In a MPLS VPN OSPF routing info is sent in BGP updates between PEs. The metric is copied to the BGP MED value of the VPNv4 update.

Do you modify MED during redistribution, which could explain the observed behaviour?

Do you have OSPF external type 1 or type 2 routes?

Could you post the relevant PE router config? This would help to analyze the problem.

Regards, Martin

Community Member

Re: OSPF, neighbors and routes

Thanks Marting,

There is no modification of MED during distribution.

They are showing as E2 routers, but what determines that?

I will try to post a config soon

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