[frr] 2 MPLS Questions

Renato Westphal renato at opensourcerouting.org
Sat Mar 18 08:50:12 EDT 2017


On Sat, Mar 18, 2017 at 7:27 AM, Jeff Tantsura <jefftant at gmail.com> wrote:
> That's only needed with label per VRF mode, and if I recall correctly in currently supported/discussed label per prefix mode where POP is followed by IP lookup in VRF context. IMHO - would be really bad (why repeat bad early IOS choices?)
> The most optimal case for FRR would be label per NH allocation, where label lookup should yield fully resolved adj, withno need for additional lookup.
> It would also support the case with >1 NH's in a VRF (multihoming).
>
> There are some corner cases, like EIBGP LB + BGP FRR, however we are rather far away from that point in life...

Yes, pop+route lookup should not be mandatory for supporting l2/l3
vpns. But apparently Olivier needs this for his Segment Routing
implementation, so I can't see why not support this in the Linux
kernel.

OpenBSD for instance allows pop+route lookup (OpenBGPD's l3vpn
implementation relies on that because it allocates one label per
VRF/rdomain).

-- 
Renato Westphal




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