Re: Some minor comments on the loose-path-opt draft
Jean Philippe Vasseur <jvasseur@cisco.com> Thu, 01 April 2004 20:08 UTC
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Date: Thu, 01 Apr 2004 14:50:28 -0500
To: raymond zhang <zhangr@info.net>
From: Jean Philippe Vasseur <jvasseur@cisco.com>
Subject: Re: Some minor comments on the loose-path-opt draft
Cc: y.ikejiri@ntt.com, ccamp@ops.ietf.org
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Hi Raymond, Thanks for your comments and support for the draft - see in line. At 09:25 AM 4/1/2004 -0800, raymond zhang wrote: >Hi JP and Yuichi, > >Just gone through >http://www.ietf.org/internet-drafts/draft-vasseur-ccamp-loose-path-reopt-00.txt >and here are some minor comments: > >This draft describes a very useful mechanism solving part of the reopt >issues documented in the inter-AS requirements draft >(http://www.ietf.org/internet-drafts/draft-ietf-tewg-interas-mpls-te-req-06.txt)... > >1. Editorial comments: > >1.1. Editorial - clean up the strange characters, for example, in Section >4.2, page 5 >" ...ªªLink-UPªª event). " ok >1.2. Section 1, page 2, " >A loosely routed explicit path is as a path specified as a ..." > > >The "as" proceeding "a path" above should be removed. right, thanks. >1.3. Section 1, page 2, "...of the Ipv4 prefix sub-object..." >should IPv6 prefix be included as well ? > >Also in Section 3.2, may need to list a IPv6 error_spec object also... Agree, we'll fix that, >1.4. In section 4.3.1, page 7: > >"Example: > >Let call " > >It should be "Let's call..." ok >1.5. In section 4.3.1, page 7: >"... pi such that li is a next (loose) hop of pi for i=1+n" > >- delete "pi" >- "i=1+n" should be changed to "i=1 to n" >- it may read better if you change "for i=1 to n" to for "i=1 to n which >is illustrated in the following example:" > >Then after "Pn=<R1,R3,R8>" > >add "where L1=R3 is the next loose hop of P1=R1, etc." right >2. Other comments: > >2.1. In section 4.3.1, page 7 >"- If a better path can be found, the LSR MUST > immediately send a Path Error to the head-end LSR > (Error code 25 (Notify), sub-code=6 (better path > exists))" > >I wonder if you should also add "and go ahead with reopt by sending RSVP >path messages for the new path". Otherwise there is no action described >for this mid-point LSR what it will do after it found a better path and >notify the HE LSR. In this case, the TE LSP is contiguous, hence the mid-point's role is just to notify of the existence of a better path (or the requirement for local maintenance) in some downstream area/AS. Note that it cannot locally reoptimize since the LSP ID would not match. Moreover, the intention is to let the Head-end LSR decide on whether to reoptimize depending on the TE LSP attributes (pending back-off, ...). Does that make sense ? >2.2. Some general comments regarding the mode of operations > >There are couple more cases which may be considered: > >Mode 1 If it is TE-LSP HE LSR initiated, >- Midpoint LSR can ignore this request and not to perform reopt even if >there is a better path within its AS; > >This can either be part of the interconnect agreement between two >providers or to protect transit AS for reasons such as HE LSR triggers >reopt in an unusually high frequency due to mis-configuration... But >mid-point LSR does need to notify the HE LSR why via patherr msg. Totally agree, this is a good point which will be in the next revision. >Mode 2 If it is mid-point LSR initiated and midpoint LSR find out there is >a better path for an existing TE-LSP and notifies the TE-LSP HE, TE-LSP HE >LSR does not want to reopt, for example, configured not to repot that way >for operational reasons at that time. (except for local link maint. >reasons of course) I am not sure what's the process here next - both HE >and midpoint LSR do nothing and continue to refresh ? Yes, head-end and the mid-point LSRs could respectively ignore the polling and the notification but this is again a good point which is worth being clarified. Thanks for your useful comments: they will be incorporated in the next revision. JP. >Regards, >Raymond > > >
- Re: Some minor comments on the loose-path-opt dra… Jean Philippe Vasseur
- Re: Some minor comments on the loose-path-opt dra… raymond zhang
- Re: Some minor comments on the loose-path-opt dra… Jean Philippe Vasseur