Re: [mpls] I-D ACTION:draft-ietf-mpls-p2mp-sig-requirement-03.txt
"Adrian Farrel" <adrian@olddog.co.uk> Wed, 06 July 2005 22:45 UTC
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From: Adrian Farrel <adrian@olddog.co.uk>
To: neil.2.harrison@bt.com, yasukawa.seisho@lab.ntt.co.jp
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Subject: Re: [mpls] I-D ACTION:draft-ietf-mpls-p2mp-sig-requirement-03.txt
Date: Wed, 06 Jul 2005 23:47:41 +0100
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Hi Neil, Speaking as a co-author of draft-ietf-mpls-p2mp-sig-requirement-03.txt and of draft-yasukawa-mpls-p2mp-oam-reqs-00.txt I can give an answer. Seisho may want to comment further. "protected by" is certainly not supposed to suggest that each and every fault can be rectified by fast error recovery mechanisms. And, of course, it would be crazy to expect that since failures of, for example, the ingress router are not recoverable. So, yes, "protected by" refers to defects that are protectable and reported/detected, and only applies if the service has actually been protected. As you say, fault rectification is only going to take place if it is detected in or reported to the layer in which we are deploying P2MP MPLS TE. Further, as we attempt to say in the P2MP OAM requirements draft (and/or inherit from the P2P OAM requirements draft) the higher layer must be careful not to react too precipitously to a fault which the lower layer may be in the process of solving. With regard to "non-objectives". The non-objectives stated are NOT non-objectives of the MPLS WG wrt to P2MP TE signaling. They are non-objectives of *this* I-D. As the specific OAM subsection states, P2MP OAM is discussed in a separate I-D. There are three reasons for this: 1. OAM is not really a signaling requirement. 2. It is sufficiently large and important that folding it into the signaling requirements I-D would make the signaling requirements I-D unwieldy. 3. P2MP OAM needs to apply more widely than just TE (e.g. to LDP multicast) Cheers, Adrian ----- Original Message ----- From: <neil.2.harrison@bt.com> To: <yasukawa.seisho@lab.ntt.co.jp> Cc: <mpls@ietf.org> Sent: Wednesday, July 06, 2005 11:32 AM Subject: RE: [mpls] I-D ACTION:draft-ietf-mpls-p2mp-sig-requirement-03.txt Seisho, I have a question on this draft: In section 1 there is the following stated requirement: "A P2MP TE LSP will be protected by fast error recovery mechanisms to minimize disconnection of a P2MP service." Which is obviously sensible, and of course implies that all the defect cases of interest can be detected and the appropriate consequent actions taken. Note this should include defects of this layer network and not just defects that arise in lower layer networks. And remember....the links between nodes in this layer network are provided by (p2p) trails in a lower layer network....and this client/server relationship recurses to the duct. The point I am making here is that IF the lower layer network has decent OAM itself you should get some indication of failure from this, but this is over/above any defects you detect in this layer network either from (i) lower layer defects or (ii) defects arising in this layer network (which of course cannot be detected at all in any lower layer network). Yet it says in section 1.1 that a 'non-objective' is: "OAM for P2MP LSPs" Can someone please explain this apparent contradiction? regards, Neil _______________________________________________ mpls mailing list mpls@lists.ietf.org https://www1.ietf.org/mailman/listinfo/mpls _______________________________________________ mpls mailing list mpls@lists.ietf.org https://www1.ietf.org/mailman/listinfo/mpls
- [mpls] I-D ACTION:draft-ietf-mpls-p2mp-sig-requir… Internet-Drafts
- RE: [mpls] I-D ACTION:draft-ietf-mpls-p2mp-sig-re… neil.2.harrison
- Re: [mpls] I-D ACTION:draft-ietf-mpls-p2mp-sig-re… Adrian Farrel
- Re: [mpls] I-D ACTION:draft-ietf-mpls-p2mp-sig-re… Seisho Yasukawa