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RE: I-D ACTION:draft-ietf-ccamp-inter-domain-recovery-analysis-01.txt



Hi Dimitri,

Please see in-line.

At 19:54 07/07/10, PAPADIMITRIOU Dimitri wrote:
>hi tomonori - see inline
>
>> -----Original Message-----
>> From: Tomonori TAKEDA [mailto:takeda.tomonori@lab.ntt.co.jp]
>> Sent: Tuesday, July 10, 2007 9:51 AM
>> To: PAPADIMITRIOU Dimitri; ccamp@ops.ietf.org
>> Subject: RE: I-D
>> ACTION:draft-ietf-ccamp-inter-domain-recovery-analysis-01.txt
>>
>> Hi Dimitri,
>>
>> Thanks for your comments.
>>
>> Please see in-line.
>>
>> At 06:10 07/07/10, PAPADIMITRIOU Dimitri wrote:
>>  >tomonori
>>  >
>>  >
>>  >reading through this doc still unclear to me why there is
>> no statement
>>  >that says (at the end) that the sole issue is due to the fact that
>>  >ingress node do not see both protecting and working LSPs
>> (by definition
>>  >of diversity) and therefore across that domain, mechanisms
>> are needed:
>>  >
>>  >
>>  >1. since the problem is only considered in its linear version and
>>  >associated protecting and working LSP are are both
>> following the same
>>  >sequence, one needs to resolve the intra-domain/intra-AS
>> trap issue (at
>>  >the SRLG/node/ link level) and prevent that that two
>> ingress nodes (of
>>  >the same domain) do not select the same egress node (of
>> that domain) to
>>  >reach the next domain for both protecting and working LSP ?
>>
>> This is true when there are only two border nodes (ingress
>> and egress) for
>> each domain (well, SRLG diversity where nodes/links in
>> different domains
>> belong to the same SRLG is a bit hard, though).
>
>this is what the diagrams and text infers
>
>generalizing the number of edges/inter-connection
>adds an additional constraints (select 2 among N)

Section 1.3 and section 2 state the problem space. This document does not restrict that the number of border nodes must be 2.

>> However, when there are more than two border nodes, we need
>> to pick up a
>> good pair of border nodes. Please see my separate email to
>> Meral which
>> shows such an example.
>
>idem keep in mind here that enlarging the problem
>space and have a preferential selection between N
>possible inter-domain links but achieve a non-
>blocking situation is the base objective
>
>>  >2. when computation is not simultaneous per domain (independently of
>>  >whether sequentially distributed or centralized) and does
>> not result in
>>  >strict hops only (implicitly or explcitly), the only thing
>> that remains
>>  >possible is to condition the first LSP setup with
>> additional constraints
>>  >during its establishment
>>
>> I am not sure whether I understand correctly, but if border nodes are
>> already selected, the only thing that remains is to select
>> the route within
>> each domain.
>
>yes and the question boils down to the point mentioned
>where intra-domain path comp. would result in blocking
>the other
>
>i don't see any answer to the below point ? which is at
>the end the reason of my comment - this doc bundles the
>protocol independent analysis with a protocol dependent
>analysis in the latter case one should consider possible
>solution space and not pre-assume any specific limitation

I think this document is based on existing framework (or schemes), which is RFC4726. RFC4726 states several schemes for inter-domain TE, like domain boundary computation (per-domain path computation) and PCE-based computation (inter-domain collaborative path computation).

I think this document is not heavily dependent on protocols (but dependent on existing framework).

- Is there any missing scheme (other than listed in sections 4 and 5)?
- Is there anything to add/modify for some schemes?
- Or something else?


Thanks,
Tomonori

>thanks,
>-d.
>
>> Thanks,
>> Tomonori
>>
>>  >this would for me streamline this analysis in a protocol
>> independent way
>>  >(observe that point 2 is totally independent of whether
>> PCEs are used or
>>  >not)
>>  >
>>  >
>>  >now if a protocol analysis needs to be done it needs to
>> account for call
>>  >segments in which case and compared to BRPC the discussion would be
>>  >about sequential computation along the downstream or the
>> upstream (or
>>  >combination)
>>  >
>>  >
>>  >thanks,
>>  >-d.
>>  >
>>  >
>>  >
>>  >
>>  >
>>  >
>>  >> -----Original Message-----
>>  >> From: owner-ccamp@ops.ietf.org
>>  >> [mailto:owner-ccamp@ops.ietf.org] On Behalf Of Tomonori TAKEDA
>>  >> Sent: Monday, July 09, 2007 4:04 AM
>>  >> To: ccamp@ops.ietf.org
>>  >> Subject: Fwd: I-D
>>  >> ACTION:draft-ietf-ccamp-inter-domain-recovery-analysis-01.txt
>>  >>
>>  >> Hi,
>>  >>
>>  >> A new version of inter-domain recovery analysis I-D have been
>>  >> published.
>>  >>
>>  >> Here are major changes:
>>  >> - Added text on security considerations section
>>  >> - Cleaned up text marked "for further study" (various places)
>>  >> - Added a reference to [PCEP-XRO]
>>  >> - Enhanced text on computing diverse paths sequentially with
>>  >> confidentiality
>>  >>    (Section 5.4.1)
>>  >> - Moved "terminology" section into "introduction" section
>>  >> - Removed manageability considerations section
>>  >> - Polished text
>>  >>
>>  >> Authors believe the document is now completed and ready for
>>  >> WG last call.
>>  >>
>>  >> Thanks,
>>  >> Tomonori
>>  >>
>>  >>  >To: i-d-announce@ietf.org
>>  >>  >From: Internet-Drafts@ietf.org
>>  >>  >Date: Fri, 06 Jul 2007 14:15:01 -0400
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>>  >>  >Subject: I-D
>>  >> ACTION:draft-ietf-ccamp-inter-domain-recovery-analysis-01.txt
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>>  >>  >10:31:19,dmn=5.3.14/2007-05-31
>>  >>  >
>>  >>  >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		: Analysis of Inter-domain Label
>>  >> Switched Path (LSP) Recovery
>>  >>  >	Author(s)	: T. Takeda, et al.
>>  >>  >	Filename	:
>>  >> draft-ietf-ccamp-inter-domain-recovery-analysis-01.txt
>>  >>  >	Pages		: 23
>>  >>  >	Date		: 2007-7-6
>>  >>  >
>>  >>  >This document analyzes various schemes to realize
>>  >> Multiprotocol Label
>>  >>  >   Switching (MPLS) and Generalized MPLS (GMPLS) Label
>> Switched Path
>>  >>  >   (LSP) recovery in multi-domain networks based on the existing
>>  >>  >   framework for multi-domain LSPs.
>>  >>  >
>>  >>  >   The main focus for this document is on establishing
>> end-to-end
>>  >>  >   diverse Traffic Engineering (TE) LSPs in multi-domain
>>  >> networks. It
>>  >>  >   presents various diverse LSP setup schemes based on existing
>>  >>  >   functional elements.
>>  >>  >
>>  >>  >A URL for this Internet-Draft is:
>>  >>
>>  >> >http://www.ietf.org/internet-drafts/draft-ietf-ccamp-inter-do
>>  >> main-recovery-analysis-01.txt
>>  >>  >
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