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mada3k
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Location: Sweden

Migrate OSPF to OSPF+MPLS+BGP

Fri Nov 08, 2019 2:39 pm

We are currently running an OSPF with 4 sub areas. We do have some area range/summarization in place but currently all "edge" networks is within same OSPF instance and is not easily summarized for the moment. We are running MPLS on some links today, for some VPLS tunnels.

To speed things up and to take the ease of OSPF we are exploring to migrate the "edge" networks to BGP with recursive routing (OSPF+BFD+MPLS+BGP) We have done some laboration with a a couple of CHRs and it works great, using the "hub"-routers with route-reflection.

Any one running this kind of setup or having some suggestions/issues with it?

R1 ----> R2 -----> R3

If I understand correctly:
  • The routes gets installed (R1) by BGP with the foreign Router-ID (nexthop self) in the system table. This is not direct routable via L3 but the MPLS layer has an label for that Router-ID, thus it gets forwarded out with that label.
  • On the neighbouring routers (R2) it has the same Router-ID in its MPLS forwarding table and just swaps the label for the appropriate one.
  • When it arrives at the target router (R3) with that Router-ID, it drops the label, and then of course it has that network in it's local routing table.
Thanks
Manages some CCR's, RB750Gr3, RB922 and wAP's

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