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RE: I-D ACTION:draft-ietf-ccamp-lsp-stitching-01.txt
Hi Arthi,
Please see inline
> -----Message d'origine-----
> De : Arthi Ayyangar [mailto:arthi@juniper.net]
> Envoyé : jeudi 28 juillet 2005 18:17
> À : LE ROUX Jean-Louis RD-CORE-LAN
> Cc : ccamp@ops.ietf.org; jpv@cisco.com
> Objet : RE: I-D ACTION:draft-ietf-ccamp-lsp-stitching-01.txt
>
> Hi JL,
>
> Thanks for the comments.
>
> > -In section 4.1.2 you partially describe bidirectional LSP
> stitching
> > procedure. You mention that an Upstream Label MUST NOT be
> allocated by
> > the end-to-end LSP on the LSP segment, which is OK. But
> then how the
> > LSP-Segment Egress will now that the end-to-end LSP is
> bidirectional?
> AA--------> Excellent point.
>
> > What about defining a flag in the Attributes Flags TLV of the
> > LSP_ATTRIBUTE object so as to indicate that the LSP is
> bidirectional?
> AA------> That would be a change to the processing that GMPLS
> nodes use
> AA------> to
> detect bidirectionality, isn't it ? Normally nodes look for
> the Upstream Label object to detect bidirectionality.
>
> So let us say that an LSP is bidirectional if a) an Upstream
> Label is present or b) no Upstream Label, but bit set in
> LSP_ATTRIBUTE or c) both However, reliance on an e2e
> attributes bit set by head end, means existing head ends will
> not be setting this bit, so that will be an issue (wrt compatibility).
JLLR: I agree this may raise some backward compatibility issues.
This would require that head-ends be upgraded...
>
> Could be nice if this signaling was just between the node
> doing the stitching and the end point of the LSP segment,
> since this is the hop that the bidirectionality information
> is lost. Let me think about this.
JLLR: Yes, and what about defining a new MPLS label value, let say label 4 = "No label assigned", with a semantic distinct from label 3 semantic (=label pop). The UPSTREAM label object with this new label value would be included in the end-to-end Path message over the LSP-Segment...
Let discuss this point during Paris meeting,
Regards,
JL
>
>
> > Also the selection of the LSP segment in case of bidirectional LSP
> > should be detailed (e.g. If the end-to-end LSP is
> bidirecitonal then
> > the LSP-segment MUST be bidirectional. Also shall we allow that two
> > unidrectional end-to-end LSP use the same bidirectional LSP segment
> > (one in each direction)?
> AA----> Yes, this should be okay. IMO.
>
> > -At the end of section 4.2.5 you mention that LSP-Segment
> failure or
> > maintenance SHOULD be treated as a failure event for the
> end-to-end LSP.
> > I agree for LSP-Segment failure but not for LSP-Segment maintenance.
> > LSP-Segment maintenance should be treated as TE-link
> maintenance for
> > the end-to-end LSP, and procedures defined in GMPLS
> graceful TE-link
> > shutdown draft may be useful (Specific RSVP error code and TE-link
> > attribute)...
> AA---> Yes, I agree; we will mention this. Actually the graceful
> AA---> teardown
> sentence occurs few paragraphs before, but not in the right
> context. So we will clarify the above.
>
> > Hope this helps,
> AA---> Sure does.
>
>
> Thanks!
>
> -arthi
>
> >
> >
> > > -----Message d'origine-----
> > > De : owner-ccamp@ops.ietf.org
> > > [mailto:owner-ccamp@ops.ietf.org] De la part de
> > > Internet-Drafts@ietf.org Envoyé : vendredi 15 juillet
> 2005 21:50 À :
> > > i-d-announce@ietf.org Cc : ccamp@ops.ietf.org Objet : I-D
> > > ACTION:draft-ietf-ccamp-lsp-stitching-01.txt
> > >
> > > A New Internet-Draft is available from the on-line
> Internet-Drafts
> > > directories.
> > > This draft is a work item of the Common Control and Measurement
> > > Plane Working Group of the IETF.
> > >
> > > Title : Label Switched Path Stitching with
> > > Generalized MPLS Traffic Engineering
> > > Author(s) : A. Ayyangar, J. Vasseur
> > > Filename : draft-ietf-ccamp-lsp-stitching-01.txt
> > > Pages : 19
> > > Date : 2005-7-15
> > >
> > > In certain scenarios, there may be a need to combine together two
> > > different Generalized Multi-Protocol Label Switching
> (GMPLS) Label
> > > Switched Paths (LSPs) such that in the data plane, a
> single end-to-
> > > end (e2e) LSP is achieved and all traffic from one LSP
> is switched
> > > onto the other LSP. We will refer to this as "LSP
> stitching".
> > > This
> > > document covers cases where: a) the node performing
> the stitching
> > > does not require configuration of every LSP pair to be stitched
> > > together b) the node performing the stitching is not
> the egress of
> > > any of the LSPs c) LSP stitching not only results in
> an end-to-end
> > > LSP in the data plane, but there is also a
> corresponding end-to-end
> > > LSP (RSVP session) in the control plane. It might be
> possible to
> > > configure a GMPLS node to switch the traffic from an LSP for
> > > which it
> > > is the egress, to another LSP for which it is the
> ingress, without
> > > requiring any signaling or routing extensions whatsoever,
> > > completely
> > > transparent to other nodes. This will also result in
> LSP stitching
> > > in the data plane. However, this document does not cover this
> > > scenario of LSP stitching.
> > >
> > > A URL for this Internet-Draft is:
> > > http://www.ietf.org/internet-drafts/draft-ietf-ccamp-lsp-stitc
> > hing-01.txt
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