The MPLS WG Archive

["Brijesh Kumar" <bkumar@ennovatenetworks.com>]

In his last mail, Jeremy Lawrence writes

> At 16:16 05/25/2000 +0530, Naveen Seth wrote:
> >Hi,
> >The definition of MPLS domain in the
> draft-ietf-mpls-arch-06.txt says that the MPLS nodes are in
> one routing or administrative domain.
> >
> >1. Does it imply that we cannot have 2 AS(Autonomous System)
> within the same MPLS domain?
>
> This is possible only under very restricted circumstances. Consider
> the ASBRs of two adjacent ASes. If either or both ASBRs summarize
> eBGP routes before distributing them into their IGP, or if there is
> any other set-up where the IGP routes cover a set of FECs which
> differs from that of the eBGP routes (and this would almost always
> be the case), then the ASBRs cannot forward traffic based on the
> top-level label. A similar argument applies to TE tunnels. Some
> traffic usually will be either IP forwarded by the ASBR, or

Well... This is inconsistent with the MPLS Arch document.

A MPLS domain is defined in MPLS architecture document as "a contiguous set
of nodes which operate MPLS routing and forwarding and WHICH ARE IN *ONE
ROUTING OR ADMINISTRATIVE DOMAIN*".

This means that a MPLS Domain, at most, can cover one Administrative Domain.
Any other implementation (i.e., an MPLS domain being defined as part of two
administrative domain) is not in line with this definition. Whether this
should be the case or not, is all together different issue.


Cheers,

--brijesh
Ennovate Networks Inc.