[c-nsp] ASR9k eBGP multihop with peer in leaked route

Nathan Ward cisco-nsp at daork.net
Fri Jun 10 09:47:20 EDT 2016


Hi all,

Bit of a weird one..

I have an eBGP multihop session I’m trying to configure in a VRF, that I’ll call VRF Internet.
The peer address is in another VRF that I’ll call VRF Transit, and is leaked in to VRF Internet.
I’ve got a local loopback for the eBGP multihop source address, in VRF Internet, which is leaked in to VRF Transit.
The next-hop of the /23 for the multihop peer is learned over eBGP to a transit provider, and is leaked from VRF Transit in to VRF Internet.

The route for the multihop peer exists, and I can ping the peer fine from the source address that I have configured on the BGP session, however, the session stays in state "Idle (No route to multi-hop neighbor)”.

If I create a static route that mirrors the leaked route, things seem to work fine (well, it sits in active state, I think the remote peer is not configured yet).
Additionally, I have other eBGP multihop peers elsewhere in the network that work fine when the next-hop is through a static route to another VRF.

I am not sure if this behaves differently if the leaked route is from another PE - I don’t really have an easy way to test that at the moment, so I’m not sure if it’s caused by the route being a local route or not.

Are there some funny rules that are preventing eBGP multihop from coming up when the peer address is learned over a leaked route? Or.. a leaked route from the local PE?

--
Nathan Ward



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