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Re: Progressing the three inter-domain I-Ds
On Jan 13, 2007, at 6:49 AM, Dimitri.Papadimitriou@alcatel-lucent.be
o) a couple of generic comments on the third doc
- the doc. states applicability to GMPLS but sometimes only ref.
signaling further on e.g. section 3.1
" - The inter-domain TE LSPs are signaled using RSVP-TE ([RFC3209])."
and many others in section 4.
- the are many comparison with PCE technique along the doc. - well
fine but outside the scope of the document except if the purpose is to
indicate how different techniques can be combined together and which
interop issues may result from it
Because there are indeed two path computation techniques, it is
useful to keep these references in order to provide a fair
comparison. We could of course come up with a separate applicability
ID, but there are already quite a few related IDs, thus it is
preferable to keep the text here. I'll double check if there's any
o) a couple of specific comments
end of section 2:
section 3.1: "* The complete list of boundary LSRs along the path"
-> list of domain identifier e.g. AS numbers also applies here ?
last § of section 3.1 is the most important one, signaling protocol
independent of the routing topology itself, i.e. not because a node is
an ABR or an ASBR that comp. occurs but simply because he has no path
to reach the next (loose) hop - an intermediate node should still
capacity to perform such operation
section 3.3 "The path computation
technique described in this document applies to the case of a
AS made of multiple IGP areas, multiples ASs made of a single IGP
areas or any combination of the above. For the sake of simplicity,
each routing domain will be considered as single area in this
-> not sure to understand the reasoning, at the end these examples
remain illustrative and not restrict applicability - all these
like material should better go in an appendix -
Not sure why ?
section 3.1 "In any case,
no topology or resource information needs to be distributed between
domains (as mandated per [RFC4105] and [RFC4216]), which is
to preserve IGP/BGP scalability and confidentiality in the case
LSPs spanning multiple routing domains."
then Section 4
"In terms of computation of an inter-AS TE LSP path, an interesting
optimization technique consists of allowing the ASBRs to flood
information related to the inter-ASBR link(s) although no IGP TE is
enabled over those links (and so there is no IGP adjacency over the
inter-ASBR links). ...
"Thanks to such an optimization, the inter-ASBRs TE link information
corresponding to the links originated by the ASBR is made available
in the TED of other LSRs in the same domain that the ASBR
"Note that no topology
information is flooded and these links are not used in IGP SPF
computations. Only the TE information for the outgoing links
directly connected to the ASBR is advertised."
-> can one of the author clarify 1) is flooding involved or not ?
I'll be happy to clarify. The idea is to flood the TE info for the
Inter-AS link(s). Note that this does not contradict the requirements
(1) Confidentiality relates to the topology of another domain: the TE
information flooded in a domain is only augmented by Inter-AS links,
not to any link in another domain.
(2) Scalability: of course, flooding the TE info of a few Inter-AS
links will not compromise the scalability of the IGP.
2) what get's flooded and under which conditions 3) what is the
scope of the flooding 4) how this mechanism positions against the
requirements of 4105 and 4216
Did I clarify ? If so, I'll add a paragraph in the ID.
o) a couple of edits
ABR Router, ASBR Router - redundant R
the most important def. is the "domain" def. which can be found in the
frm doc but not recorded here this would clarify sentence like
"The mechanisms proposed in this document are also applicable to MPLS
TE domains other than IGP areas and ASs."
ref. H-LSP and S-LSP with the appropriate docs
state that inter-domain recovery is going to be addressed in a set of
Thanks for the edits.
hope this will help,
"Adrian Farrel" <firstname.lastname@example.org>
Sent by: email@example.com
Please respond to "Adrian Farrel"
Subject: Progressing the three inter-domain I-Ds
We now have updated versions of the three inter-domain signaling I-Ds:
Our plan is:
1. WG chairs do detailed review over the next couple of weeks
2. Editors apply necessary updates
3. We hold a WG last call for the three I-Ds together
If you are interested in this work, I suggest that now might be a good
to remind yourself about the I-Ds, have a good read, and see if you
any substantial comments in to coincide with the WG chairs' review.