The problem of re-distributing IBGP routes to IGP routing protocols

In the network, R1 and R2 run the BGP routing protocol and IBGP, R2, and R3 run OSPF. This topology is mainly used to test the routing redistribution problem between IBGP and OSPF.

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After configuring the basic IP address, ospf, and bgp routing protocols, perform the single-point bidirectional re-distribution of ibgp and ospf on R2. After the re-distribution configuration is completed, it is found that routes on R1 can be learned on R3, but routers on R3 cannot be learned on R1. Check that the redistribution configuration is correct.

After some consideration, ibgp is widely distributed to the igp routing protocol in common enterprise applications. ibgp is generally used to transmit External bgp routing information within the, the AS internal route is generally directly in the igp route table; however, on the PE router of the mpls vpn application provided by the carrier, the PE router needs to be the ibgp route learned through the MP-BGP, resend to the IGP of the vrf corresponding to the customer CE. As a result, after looking back to the previous situation and finally querying and verifying through experiments, CISCO and Huawei routers are not allowed to re-distribute ibgp routes to ospf by default, (The estimation of other igp routing protocols is similar). If you confirm that the ibgp routing protocol needs to be re-distributed to ospf, additional configurations need to be added.

 

CISCO

Add a command in the bgp process: bgpredistribute-internal.

 

Huawei

Add the import-routebgp permit-ibgp command in the ospf process. When This command is added, the Huawei router may have the risk prompt: "Info: This configuration may result in loops. please do not configure mthis configuration if not necessary."

 

For ebpg routes, they can be directly re-distributed to the ospf routing protocol.

 

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The problem of re-distributing IBGP routes to IGP routing protocols