The MPLS WG Archive

[Eric Gray <egray@sandburst.com>]

Ramyanshu,

    I assume you're talking about RFC 2547.  Another RFC on
VPNs over MPLS (RFC 2917) mentions BGP only to say that
- unlike RFC 2547 - it does not require BGP.  Note that RFC
2547 is entitled simply "BGP/MPLS VPNs".

    This RFC currently enjoys an 'Informational' status, it does not
attempt to represent itself as the one and only way of doing VPNs
using MPLS and it's actually an RFC on BGP based VPNs using
MPLS.  It cannot therefor be surprising that it uses BGP for VPN
route distribution.  :-)

    Any scheme which allows provider 'edge' devices (any kind of
device - not necessarily a router) to establish a label distribution
relationship with possibly remote other provider 'edge' devices -
and ensures that intermediate systems (if any) will forward packets
between these devices without modifying the labels distributed -
can be used to support a VPN service over MPLS.

    It happens that BGP is aptly suited to this purpose in certain
applications, with only relatively minor enhancements.  It is also
the case that there are numerous concerns about the scalability
of route table sizes using this approach in other applications.

--
Eric Gray

You 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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