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Sync issue with BGP route reflector and OSPF

have the following test network set up as follows:


AS1 ----AS3---

- R1 is under AS1. R2,3 and 4 are under AS3

- BGP neighborhood are built between R1-r2, r2-r3, r3-r4

- r3 is the route reflector

- OSPF is the IGP throughout AS3. R2 redistribute bgp into ospf

- Link between R1-R2 is in OSPF domain as well

R1 has a network injected into BGP. This route shows up in the routing table of R2, 3 and 4. The problem is that R4 learns from BGP but regards it as unsynchronized.

additional observations are:

- Of courese, "no sync" in R4 will solve the problem but I want it to remain sync

- Next hop is not an issue as R2, R3 and R4 can ping the interface of R1

- By replacing OSPF by eIGRP, all problems are resolved

- Kick out route reflector and build fully meshed peer among R2, r3 and R3. The problem is solved as well.

So it leads me to think with OSPF, the requirement of sync goes beyond learning route through IGP. I have seen the following cisco doc that says they match router ID as well but it is not quite clear:

Can someone clearly tell me what have to be matched.



Re: Sync issue with BGP route reflector and OSPF

Often times complex troubleshooting issues are best addressed in an interactive session with one of our trained technical assistance engineers. While other forum users may be able to help, it’s often difficult to do so for this type of issue.

To utilize the resources at our Technical Assistance Center, please visit and to open a case with one of our TAC engineers, visit

If anyone else in the forum has some advice, please reply to this thread.

Thank you for posting.