[c-nsp] inter-as mp-bgp with ttl-security issue

[Vitkovsky, Adam]

I just ran across this issue again so I decided to find some reasonable explanation if there's one

I've just set up a vpnv4 session between two inter-as route-reflectors (7200s runing 12.2(33)SRE4)
Since it's MP-eBGP session I either can use "ebgp-multihop" or "ttl-security" to manipulate the ttl in bgp packets allowing them to pas between AS domains

Now here's the catch:
If I decide to use "ttl-security" in the session template on both ends I won't get routing updates across the established session
Reason according to debug: -- DENIED due to: non-connected MP_REACH NEXTHOP;, label 18
-which is not true as the Inter-AS-route-reflector has a route to the originating PE in the other AS route is pointing to the ASBR connecting to the other AS
And the label-switched-path exist as verified by the mpls ping between the inter-as-route-reflector and the PE in other AS

However when I deconfigure the "ttl-security" and use "ebgp-multihop" instead and reset the session I'll get all the inter-as vpnv4 routes -no issues




Adam Vitkovsky CCIP(r) CCNP(r) certified
System Engineer | AT&T Business Solutions - Global Customer Service
Phone: +421-269-257-375
Email: av0025 at att.com<mailto:av0025 at att.com>

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