iBGP Next-Hop Self

[davidhuynh5]

Is the next-hop self USUALLY for ibgp peering or is it also frequently used between ebgp peering?

Thanks in advance.

[Jerry Ye · Accepted solution]

Only needed for iBGP since iBGP preserve the next-hop attribute learned from the eBGP peer.

It is not needed for eBGP.

Please see the following link for BGP FAQ:

http://www.cisco.com/en/US/tech/tk365/technologies_q_and_a_item09186a00800949e8.shtml#eleven

HTH,

jerry

[ecisco1010]

Right said.eBGP to eBGP next-hop-self has no significance. It is used only for communication between iBGP speakers.

The next-hop attribute remains unchanged while the message is fowarded to an iBGP speaker in same AS, and this can cause anomaly. The iBGP speaker may never know how to reach the mentioned next-hop (that of eBGP speaker in another AS) and thus packet will get discarded. With next-hop-self mentioned, the attribute modifies as the message is forwarded to iBGP speakers. While forwarding data, iBGP speakers simply look at next-hop attribute and forward data to their very next iBGP speaker.

Regards.