I am trying to create a BGP simulation in GNS3.

I have the following topology network topology

Here's what I have understood:

R1 will advertise

R2 will advertise

R3 will advertise

R4 will advertise,,

Since, the next hop is not changed in iBGP sessions, I will either have to use neighbor next-hop-self command or add IGP.'

I am adding IGP. In AS 200 for R3 I will have to add and Similarly for R2 I will have to add and

If I choose to add RIP or OSPF with same process ID in AS 200 and AS 300 then doing IGP will share the routing information of AS 200 and AS 300 with each other using IGP. How do I fix this?

1 Answer 1


The answer is actually very easy: make sure R3 and R4 do not form an IGP neighbor relationship. You do this by configuring the serial interface between those routers as "passive" only.

A passive interface does not send or receive routing protocol updates, but it is advertised in the routing protocol. For RIP you configure this:

router rip
    passive-interface s0/0

OSPF configuration is left as an exercise for the reader.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.