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Re: I-D ACTION:draft-ietf-ccamp-lsp-stitching-01.txt
Hi Igor,
Please see inline.
> 1. Why are saying that LSP Stitching is a private case of LSP Hierarchy?
> there is more differences than similarities:
> The differences are:
> 1) In case of H-LSP there is a data plane adjacency, while in case of S-LSP
> there is none (as you correctly pointed out);
> 2) In case of H-LSP there is an adaptation in data plane (label push/pop for
> PSC), while in case of S-LSP there is none - just simple cross-connecting
> ( label swap) as in case of two "native " e2e LSP adjacent segments ;
> 3) H-LSP could be used by many e2e LSPs, while S-LSP could be used by
> exactly one e2e LSP
> 4) Signaling is different - there is no label negotiation in stitching
> 5) H-LSP is used as a "true" data link, specifically there is a resource
> allocation on the H-LSP edges, while in case of S-LSP there is none
> 6) From MLN point of view, H-LSP is created in a server (lower) layer, while
> the S-LSP is created in the client (same as e2e LSP) layer.
>
> There are two similarities that I can think of:
> 1) There is a signaling and possibly routing (see below) adjacencies between
> the ends;
> 2) Both H-LSP and S-LSP could be advertised as separate TE links or as TE
> bundles
>
> I would recommend to dedicate a paragraph and enlist there similarities and
> differencies
-------> Based on the discussions on the list over the last revision, the
message that the authors received was that we do not want to go about such
a lengthy discussion of similarities and differences (NOTE that the draft
already does clearly highlight them where applicable). Instead we want
this ID to simply explain how LSP stitching functions. In other words the
idea was to make this ID a complete document by itself. But since it does
borrow concepts from the LSP hierarchy ID, just state the concepts that
are applicable or inapplicable.
> 2. Why are you saying that a TE Link based on S-LSP can be used for exactly
> one e2e LSP? Parallel S-LSPs could be advertised as a single TE link
> (bundle, see above) and hence can accomadate several e2e LSPs.
----> Igor, the draft does talk about this Bundling case.
> 3. You are saying that S-LSP does not have a routing peering. Actually, in
> this respect it is no different from H-LSP: if it is advertised as a TE link
> into the same TE domain that was used for S-LSP creation (unlikely IMO
> scenario) than it does not require the routing adjacency (in other words, it
> is an FA according to LSP-HIER definition), otherwise, it IS NOT and FA and
> does require the direct routing peering in the domain it is advertised to
> make it useful as a TE link in this domain
-----> I am sorry, but I am missing your point here completely. Are you
saying that the statement "the end points of an LSP segment do not have a
routing adjacency", is incorrect or are you saying that "this is
obvious" ? It is unclear to me what exactly your argument is. Please
clarify.
thanks,
-arthi
>
> Cheers,
> Igor
>
>
>
> ----- Original Message -----
> From: <Internet-Drafts@ietf.org>
> To: <i-d-announce@ietf.org>
> Cc: <ccamp@ops.ietf.org>
> Sent: Friday, July 15, 2005 3:50 PM
> Subject: 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:
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