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Re: Progressing the three inter-domain I-Ds

Hi,

On Jan 14, 2007, at 9:41 PM, Mach Chen wrote:


Dimitri and all,
After reading these docs I also have the same concern with you about inter-ASBR links flooding. I think, in oder to perform inter-AS path computation, inter-ASBR links fooding is desired. 

As pointed out in the document, this is not a MUST, but an optimization.


But
such kind of inter-ASBR link info should include more information than "normal" TE links do, e.g: the inter-ASBR links info SHOULD still include the peer AS number and peer ASBR router id besides those link info which has been specified in rfc3630 and rfc3784.
I don't think that the peer AS number info should be included in the IGP for sure. You should rely on BGP for that purpose.
So I think there need a document to clarify and specify inter-ASBR links flooding. we are considering to write such a document. If someone interested in such work, we could cooperate. 



JP.




Best regards,

Mach

----- Original Message -----
From: <Dimitri.Papadimitriou@alcatel-lucent.be>
To: "Adrian Farrel" <adrian@olddog.co.uk>
Cc: <ccamp@ops.ietf.org>; <owner-ccamp@ops.ietf.org>
Sent: Saturday, January 13, 2007 7:49 PM
Subject: Re: Progressing the three inter-domain I-Ds


hi adrian

o) a couple of generic comments on the third doc
- the doc. states applicability to GMPLS but sometimes only ref. MPLS-TE 
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 that's 
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

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 are 
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 maintain 
capacity to perform such operation

section 3.3 "The path computation
technique described in this document applies to the case of a single 
   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
   document. "
-> not sure to understand the reasoning, at the end these examples must remain illustrative and not restrict applicability - all these tutorial 
like material should better go in an appendix -

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 critical to preserve IGP/BGP scalability and confidentiality in the case of TE 
   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 the TE 
   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 belongs to." 

but after
"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 ?
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


o) a couple of edits

section 1:

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
specific docs

hope this will help,
- d.




"Adrian Farrel" <adrian@olddog.co.uk>
Sent by: owner-ccamp@ops.ietf.org
09/01/2007 23:13
Please respond to "Adrian Farrel"

        To:     <ccamp@ops.ietf.org>
        cc:
        Subject:        Progressing the three inter-domain I-Ds


Hi,

We now have updated versions of the three inter-domain signaling I-Ds:

- draft-ietf-ccamp-inter-domain-rsvp-te-04.txt
- draft-ietf-ccamp-lsp-stitching-04.txt
- draft-ietf-ccamp-inter-domain-pd-path-comp-03.txt

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
time
to remind yourself about the I-Ds, have a good read, and see if you can 
get
any substantial comments in to coincide with the WG chairs' review.

Thanks,
Adrian