The MPLS WG Archive

[Eric Gray <egray@sandburst.com>]

Ajay,

    RD and VPN ID do not have to be interchangeable
in all cases, but I think they could be.  I don't see what
the problem is in the case you point out (so maybe I do
not understand the question).

    As I understand it, an RD is effectively a sub-table
identifier used at each BGP speaker to distinguish the
IPv4 routing entries for each VPN.  There is no need
for a common RD to be used for the entire VPN, nor
is there necessarily any reason not to.  Route sub-tables
would need to be consistent (using the same definition
of consistent that applies to the Internet now) across all
routers in the same VPN - no matter how they are
identified.

--
Eric Gray

You wrote:

> Eric,
>
> If in fact we want to use VPN ID (rfc 2685) to uniquely identify a vpn, RD and
> VPN ID may not be interchangeable in all situations.  For example, for the
> same VPN in a hub-and-spoke scenario, we may need to have 2 different RDs for
> at the hub site (since we need to keep the routes on seperate VRFs) and thus
> precluding use of vpnid in place of rd.
>
> Thoughts?
>
> -ajay
> > > -- > Eric Gray
> >
> > You wrote:
> >
> > > LDP does not have a provision to carry information like VPN-IPv4 Address
> > > Family and can't be a substitute for BGP in implementing VPN. But the core
> > > routers in the provider domain, can facilitate PE to PE communication even
> > > without BGP being enabled.
> > >
> > > Jay
> > >
> > > At 04:09 AM 9/27/01 -0700, Ramyanshu Datta wrote:
> > > >hi,
> > > >
> > > >    the present  rfc on MPLS based VPNs uses BGP for
> > > >route  distribution. Can we  use LDP in place of BGP
> > > >for the same purpose.  and has  there been any work
> > > >done in this direction. if yes then please tell me the
> > > >links where i can find information about it
> > > >
> > > >Thanks in advance
> > > >Ramyanshu
> > > >
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>
> --
> Ajay Simha
> MPLS Deployment Engineer
> IOS Technology Division
> (919) 392-3141
>
> "Study as if you were to live forever
>  Live as if you were to die tomorrow"
>
>  - Mahatma Gandhi