LSP broken at ASBR's without the next-hop-unchanged !!

[rajju]

Hi:

When using the Inter-AS MPLS option of configuring Multihop MP-eBGP b/w RR's in 2 AS's, if the RR's are not configured for next-hop-unchanged, the control plane is fine but the data plane get's broken on the 2 ASBR's - LSP broken (shows Untagged for the next-hop when it should be showing a label)?

Can someone provide a good explanation as to why the next-hop-unchanged should be used on both the RR's?

Thanks.

[mheusinger]

Hi,

can you check, whether the same next hop is in the eBGP update between RRs with or without "next-hop-unchanged"?

Regards, Martin

[rajju]

Martin:

Please ignore earlier post.

It does work with or without the next-hop-unchanged - just a new vpn label is assigned by the RR since the next-hop changes here.

So the question now is why use the next-hop-unchanged?

Thanks.

[8dstaicu]

Because you may do not want to have RR's in the forwarding path.

HTH