[j-nsp] 6PE RR & next-hop resolution best practices

[Adam Vitkovsky]

Hello James

> James Jun
> Sent: 16 May 2015 01:43
> To: juniper-nsp at puck.nether.net
> Subject: [j-nsp] 6PE RR & next-hop resolution best practices
> 
> Hello,
> 
> Consider the following scenario, typical MPLS setup:  PE -- P -- P -- PE.   The P
> core routers are serving as route-reflectors for PE's.  The topology is a RSVP
> full mesh between PE's only -- the P routers do not have LSPs to anybody,
> they're simply acting as pure signaling & thru-traffic boxes for the transiting
> LSPs between PE's.
> 
> Now, because the P core routers don't have LSPs themselves heading to
> edges, there is no 'inet.3' table to fill; thus 'ipv6-tunneling' has nothing to
> copy into inet6.3.   With P routers are acting as RRs for 6PE, you can see the
> obvious problem:  they can't resolve ipv4-mapped-ipv6 next-hops in 6PE,
> therefore closest-exit routing breaks for route-reflector clients (i.e. IPv6
> traffic to a peer in same city exits out via other coast as there is no IGP
> distance to reference).
> 
If you say that the RRs act as "thru-traffic boxes for the transiting LSPs between PE's" then they should just perform pure label switching and no IPv6 lookup.
Are you sure your IPv6 traffic is labelled correctly indeed? 
And are you sure the RRs are enabled for MPLS forwarding i.e. the label switched path between PEs crossing RRs is operational? 
I mean this could have gone unnoticed for IPv4 as the RRs happened to have all the routing information necessary for the IPv4 traffic to be forward traffic across.

> Now, short of spamming LDP or going LSP-explosion-mode on every RRs, are
> there any recommendations for best practices to cleanly feed resolution
> reference for 6PE routes to RR's?
> 
> Thank you in advance!
> James
> 

adam
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