The MPLS-OPS Archive

[Robert Raszuk <raszuk@cisco.com>]

John,

> > Not really :). Once it is allowed it lands into bgp vpnv4 data
> > structure. Then from this we do the actual import into vrfs. If the dst
> > vrf RD matches the received prefix RD the route goes into the vrf and
> > the life is cool. When RDs don't not match, but RT import allows it we
> > copy the prefix (just the net) to the new vpnv4 "branch" then insert it
> > into vrf.
> 
> so RT was made for INTER-AS and CofC scenarios with RRs.......

No. I don't get where did you get this conclusion from. 
 
> VPNs spanning across ASes with different RDs?

Yep, that is the recommended and actually used design. If you make your
registered AS # part of RD you will have globally uniqe RD pool.
 
> and what about the "label stacks"...do we still need to give 3/ 4 labels in
> the MBGP update or what..?

No. VPNV4 updates carry one VPN label. Then comes forwarding. You can
transport with LDP enabled across/bgp ipv4+label between ASBRs or just
over plane IP (we have been shipping for some time 2547 over mGRE). The
last one is equally good for inter or intra AS mpls-vpns. //Oh and don't
get upset about --- uhhh GRE that does not scale. This is mGRE
multipoint where all you need to configure is one interface on the PE
and rest happens automagically based on the recieved next hops to your
vpnv4 destinations//
 
> wasnt older plain BGPv4 easier..it simply said next-hop

Exactly as I said above. If you don't like to use MPLS for forwarding -
you don't have to. (AFAIK this is supported only on cisco boxes today).
It could be used to provide mpls-vpns over IP core as well as to provide
a hybrid (MPLS core for your services, but IP tunnels to your inter-as
peers).

{Dygresion: We also have traditional mpls over GRE - just like some
other vendors - but that one indeed would be a nightmare to use in
practice :-).
 
> there was thread about putting the remote router loopback into the IGP......
> where did that go?

??? Assuming you are talking about PE loopbacks which happen to be your
vpnv4 next hops. If so of course you should put them into the IGP !!!

Cheers,
R.

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