Re: [Teas] RtgDir review: draft-ietf-teas-p2mp-loose-path-reopt-07.txt
"Joel M. Halpern" <jmh@joelhalpern.com> Fri, 09 December 2016 02:02 UTC
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To: "Rakesh Gandhi (rgandhi)" <rgandhi@cisco.com>, "rtg-ads@tools.ietf.org" <rtg-ads@tools.ietf.org>
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From: "Joel M. Halpern" <jmh@joelhalpern.com>
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Cc: "rtg-dir@ietf.org" <rtg-dir@ietf.org>, "draft-ietf-teas-p2mp-loose-path-reopt.all@ietf.org" <draft-ietf-teas-p2mp-loose-path-reopt.all@ietf.org>, "teas@ietf.org" <teas@ietf.org>
Subject: Re: [Teas] RtgDir review: draft-ietf-teas-p2mp-loose-path-reopt-07.txt
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Those changes address my concerns. The RFC Production Center Editors may choose to discuss the abstract further (it is still a bit longer than they usually like), but they may not. I can live with it as you propose. Thank you, Joel On 12/8/16 8:57 PM, Rakesh Gandhi (rgandhi) wrote: > Hi Joel, > > Thank you for the detailed review of the document. Please see inline <RG> for replies.. > > > > > On 2016-11-23, 4:10 PM, "Joel M. Halpern" <jmh@joelhalpern.com> wrote: > >> Hello, >> >> I have been selected as the Routing Directorate reviewer for this draft. >> The Routing Directorate seeks to review all routing or routing-related >> drafts as they pass through IETF last call and IESG review, and >> sometimes on special request. The purpose of the review is to provide >> assistance to the Routing ADs. For more information about the Routing >> Directorate, please see >> http://trac.tools.ietf.org/area/rtg/trac/wiki/RtgDir >> >> Although these comments are primarily for the use of the Routing ADs, it >> would be helpful if you could consider them along with any other IETF >> Last Call comments that you receive, and strive to resolve them through >> discussion or by updating the draft. >> >> Document: draft-ietf-teas-p2mp-loose-path-reopt-07.txt >> Reviewer: Joel M. Halpern >> Review Date: 23-November-2016 >> IETF LC End Date: N/A >> Intended Status: Standards Track >> >> Summary: I have some moderate concerns about this document that I think >> should be resolved before publication is approved. >> >> Comments: >> >> Major: >> The use of SHOULD and MAY in section 4.1 seems to lead to a device >> which ostensibly supports this document, but does the wrong things. >> First, with regard to the SHOULDs, in the absence of any indication >> as to why it would not do this, it appears that the SHOULD is really >> "MUST if the device supports this document" which is what MUST in a >> document actually means. >> Section 4.2 first bullet says that a mid-point LSR "SHOULD" check >> for a preferable P2MP-TE LSP Tree. But if it doesn't, it is not >> supporting this document. As written, it could decide to ignore the >> message, even though it claims to support this RFC. >> Looking at the handling when a preferable P2MP-TE LSP tree is >> found, according to the document, the LSR MAY send the PathErr response. >> My assumption is that if it does not send the PathErr, it MUST >> propagate the request. If it does not do either one, the protocol does >> not function. It seems likely that if this is really intended to be >> optional (MAY), the document would be improved my giving implementors >> some hint as to when it is desirable or undesirable to send the message. >> Then in the third bullet, it is only a SHOULD to pass on the >> request. Thus, a device which supports this mechanism, but chooses not >> to pass on the request, is compliant to this document while preventing >> other devices from properly supporting the mechanism. > > > > <RG> Ok, how about following text in Section 4.1? > > ----------- > A mid-point LSR that expands loose next-hop(s) for one or more S2L > sub-LSP path(s) does the following upon receiving a Path message with > the "P2MP-TE Tree Re-evaluation Request" flag set: > > o The mid-point LSR MUST check for a preferable P2MP-TE LSP tree by > re-evaluating all S2L sub-LSP(s) that are expanded paths of the > loose next-hops of the P2MP-TE LSP. > > o If a preferable P2MP-TE LSP tree is found, the mid-point LSR MUST > send an RSVP PathErr with the Notify error code 25 defined in > [RFC3209] and sub-code "Preferable P2MP-TE Tree Exists (value > TBA2)" defined in this document to the ingress node. The mid- > point LSR, in turn, SHOULD NOT propagate the "P2MP-TE Tree Re- > evaluation Request" flag in the subsequent RSVP Path messages sent > downstream for the re-evaluated P2MP-TE LSP. > > o If no preferable tree for P2MP-TE LSP can be found, the mid-point > LSR that expands loose next-hop(s) for one or more S2L sub-LSP > path(s) MUST propagate the request downstream by setting the > "P2MP-TE Tree Re-evaluation Request" flag in the LSP_ATTRIBUTES > Object of the RSVP Path message. > > The sending of an RSVP PathErr with the Notify error code and > "Preferable P2MP-TE Tree Exists" sub-code to the ingress node > notifies the ingress node of the existence of a preferable P2MP-TE > LSP tree and upon receiving this PathErr, the ingress node MUST > trigger re-optimization of the LSP using the MBB method with a > > different LSP-ID. > --------------- > > > >> >> Minor: >> The abstract is much too long. Much of the content of the abstract >> belongs in the introduction. Even teh second paragraph has too much >> detail for an abstract. >> >> Editorial: >> In the last paragraph of the introduction, it says that this >> document "proposes" solutions. Given we are now in the position of >> evaluating publication as a Proposed Standard, I would say that this >> document "defines" solutions. >> > > > <RG> Ok, how about following Abstract? > > ---------- > Re-optimization of a Point-to-Multipoint (P2MP) Traffic Engineered > (TE) Label Switched Path (LSP) may be triggered based on the need to > re-optimize an individual source-to-leaf (S2L) sub-LSP or a set of > S2L sub-LSPs, both using Sub-Group-Based Re-optimization method, or > the entire P2MP-TE LSP tree using the Make-Before-Break (MBB) method. > This document discusses the application of the existing mechanisms > for path re-optimization of loosely routed Point-to-Point (P2P) TE > LSPs to the P2MP-TE LSPs, identifies issues in doing so and defines > procedures to address them. When re-optimizing a large number of S2L > sub-LSPs in a tree using the Sub-Group-Based Re-optimization method, > the S2L sub-LSP descriptor list may need to be semantically > fragmented. This document defines the notion of a fragment > identifier to help recipient nodes unambiguously reconstruct the > fragmented S2L sub-LSP descriptor list. > ---------- > > > > Thanks, > Rakesh (for authors and contributors) > > > >>
- [Teas] RtgDir review: draft-ietf-teas-p2mp-loose-… Joel M. Halpern
- Re: [Teas] RtgDir review: draft-ietf-teas-p2mp-lo… Rakesh Gandhi (rgandhi)
- Re: [Teas] RtgDir review: draft-ietf-teas-p2mp-lo… Rakesh Gandhi (rgandhi)
- Re: [Teas] RtgDir review: draft-ietf-teas-p2mp-lo… Joel M. Halpern
- Re: [Teas] RtgDir review: draft-ietf-teas-p2mp-lo… Rakesh Gandhi (rgandhi)