BGP Redistribution

[sameer_cheema]

Hello Everyone! 
i am self studying and stuck here please help me out on this.
In my topology i have three Autonomous systems of BGP. Here is what i have done.
-Each AS is runnin OSPF internally.
- R3, R4, R6 and R7 are participating in IBGP/EBGP while R1 and R9 are also participating in IBGP in their respective AS's
-Redistribution is done on all IBGP and EBGP participants. (OSPF into BGP/BGP into OSPF)

PROBLEM: After redistribution Routes are only disseminating to neighboring AS's but not beyond them.
e.g. AS-65111's routes are only getting to  AS-65222 but not to AS-65333.
-I am not sure if it is supposed to work this way but please help me if i am missing something i want to replicate my routes beyond my neighbor AS. 

[Richard Burts]

We do not have enough detail to be able to identify the issue here. Perhaps you can post the config of a couple of the routers, probably R4 and R6 to start with.

HTH

Rick

[Georg Pauwen]

Hello,

hard to say without seeing the actual configurations. How are you redistributing ? For OSPF into BGP it should look something like this:

router bgp 65111

redistribute ospf 1 match internal external 1 external 2

Post the configs of your routers (attach a .txt file otherwise the post will get way too long)...

[Harold Ritter · Accepted solution]

Hi Sameer,

One possible cause could be that you are not using the next-hop-self command between your iBGP neighbors. This command is required if you are not including the inter AS links (for example R3 to R4 link) in your IGP, in your case OSPF.

If you are not including the inter AS links in the IGP and if you do not use the next-hop-self command, the prefixes from AS65111 will be unreachable on R6 (AS65222) from a BGP standpoint, as the next hop will be unreachable and the prefixes will therefore not propagate to 65333.

Regards,

[sameer_cheema]

thanks alot Harold Ritter, now i have reachability and routes are also propagating across the neighbor AS.
Can you please suggest some documentation on next-hop-self command i want to learn a little more about it.

Cheers!