[c-nsp] redistribute routes leaked from another VRF?

Jeff Bacon bacon at walleyesoftware.com
Thu Jan 6 08:15:22 EST 2011


> More or less. You can also define an "mdt data" group range. When
> traffic for a particular (s,g) pair exceeds a configurable threshold,
a
> group is picked from this range and that (s,g) transitions to the new
> group in the default VRF, and PEs with receivers join this group. This
> means you don't flood high-bandwidth groups to every PE - just to PEs
> which are interested.

I just noticed this in SXI (only just getting there - I'm trying to read
through the release notes during morning exercise... could take weeks :(
). 

This however frightens me, because during that transition it seems as
though you're bound to drop a packet somewhere. It's ok if you're IPTV
or some other multimedia streaming, but for financial market data that's
a no-no of highest order. 

> > Plus, GRE encap with MPLS means a recirc through the EARL so you pay
the
> > latency penalty twice plus the extra load. And you need jumbo frames
to
> > encap at full standard 1500 MTU.
> I was under the impression that there's no recirc in this case, but I
> could be wrong and can't find a reference.

You may be right - GRE for tunnels requires a recirc, GRE for MVPN might
not - the recirc for the tunnel is IIRC because they have to treat the
un-encap'ed tunnel packet as if it's a new inbound packet on the tunnel
"SVI", for mdt they may be able to shortcut it. 

> As for MTU - if you're running MPLS you presumably have jumbos enabled
> anyway?

Doesn't mean your WAN provider gave you enough MTU to fit both headers,
though. (One provider I work with has all long-haul capped at 1546,
presumably a holdover from fast-enet days) 

> > Hence, don't do it if you don't have a really good reason to. I
don't,
> > so I don't.
> Well, the "good reason" for doing this is if you want multicast in
MPLS
> L3VPNs, surely ;o)

I don't want it that badly. :)

-bacon



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