On 13/12/12 14:47, Jason Lixfeld wrote:
Yes. In fact, that's *required* if you want to do multi-path.
I seem to do multi-path just fine with maximum-paths ibgp 2 on my RR
clients inside a VRF that sees a default sourced from two different
RRs. Said VRF has a common RD between the two PEs.
How is that different?
Well, AIUI multipath *ought* to require unique RDs. Obviously not; I
wonder how that's working for you?
Basically, as I'm sure you are aware, without "add paths" support, BGP
can only advertise one copy of a route - any "update" for a route
implicitly "withdraw"s a previous route.
Therefore, if your RR sends:
update nh=x.x.x.x nlri=65000:1:192.0.2.0/24
update nh=y.y.y.y nlri=65000:1:192.0.2.0/24
...then the 2nd update should wipe the first. This is why (in theory)
multipath requires a unique RD:
update nh=x.x.x.x nlri=65000:1:192.0.2.0/24
update nh=y.y.y.y nlri=65000:2:192.0.2.0/24
...are different routes.
Out of curiosity, what does:
sh ip bgp vpnv4 vrf XXX net/mask
sh ip cef vrf XXX net/mask detail
...say for one of your working multipath prefixes?
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