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Re: thoughts on draft-vasseur-ccamp-inter-area-as-te-00.txt

Hi Dimitri,

At 02:45 AM 3/2/2004 +0000, Dimitri Papadimitriou wrote:
hi arthi, jp, all,

reading draft-vasseur-ccamp-inter-area-as-te-00.txt
the following came into my mind, why is there a need
to signal the "signaling method": contiguous versus
stitching vs nesting ?

the reason provided in the document about "control"
is unclear, is the sensitivity of the carried traffic
dependent of the signaling method ?

"For the sake of illustration, a Head-end LSR, may
desire to prevent stitching or nesting for a traffic
sensitive inter-area/AS TE LSPs that require a path
control on the head-end LSR."

it seems for me that "signaling the signaling method"
introduces here in addition to the protocol issue(s),
policy issues:

"Ox01: Contiguous LSP [...]

When set, this indicates that a boundary LSR MUST
not perform any stitching or nesting on the TE LSP
and the TE LSP MUST be routed as any other TE LSP
(it must be contiguous end to end). [...]

A mid-point LSR not supporting contiguous TE LSP
MUST send a Path Error message upstream with error
sub-code=17 Contiguous LSP type not supported."

because when crossing multiple ASes this allows the head-end signalling a contiguous LSP to make sure that it will not be stitched in some downstream domain hence keeping some strict control about the reoptimization. This has to be done on a per-LSP basis, since the same head-end may not impose any such requirement for other inter-area/AS LSPs.

Thanks

JP.

thanks,
- dimitri.