The MPLS WG Archive

[Giles Heron <giles@packetexchange.net>]

Kameswara Rao Avasarala wrote:
> 
> Hi,
>    What is the application of tunneling mpls over ip ? Since LSP's cannot be
> established through a non-mpls domain and the egress lsr's anyway perform
> the transformation from mpls->ip .
> Kamesh.

But with MPLS over IP (or over GRE) LSPs *can* be established through a
non-mpls domain.  Use targetted LDP sessions ("extended discovery") or
BGP to exchange labels and then tunnel MPLS packets in IP or GRE to get
them from one device to the other...

This could be useful if you want to deploy draft-martini or RFC2547 over
a non-MPLS backbone.  The former approach is documented in draft-martini
itself (draft-martini-l2circuit-trans-mpls-07.txt) and the latter in a
companion draft to RFC2547bis (draft-ietf-ppvpn-gre-ip-2547-00.txt)

Giles

> 
> Kameswara Rao Avasarala
> Software Engineer
> Ericsson Inc
> Telephone:
> Work:805-562-6212
> Resi: 805-562-8841
> 
> -----Original Message-----
> From: owner-mpls@UU.NET [mailto:owner-mpls@UU.NET]On Behalf Of Henry
> Bibb
> Sent: Monday, September 24, 2001 11:01 AM
> To: 'mpls@uu.net'
> Subject: MPLS tunneled in IP
> 
> When MPLS-labeled packets are tunneled in IP, how does a
> router distinguish whether a given IP packet has an MPLS
> label stack or not?  In draft-worster-mpls-in-ip-05.txt,
> mention is made of setting up two new values for the IPv4
> protocol field to distinguish MPLS labelled packets, but
> there appears to be no actual code point assigned for this yet.
> 
> So, what does deployed equipment do?
> 
> Thanks,
> Henry Bibb
> Hatteras Networks, Inc.
> hbibb@hatterasnetworks.com
> 
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-- 
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Giles Heron    Principal Network Architect    PacketExchange Ltd.
ph: +44 7880 506185              "if you build it they will yawn"
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