Re: [CCAMP] [Technical Errata Reported] RFC4872 (3304)

[John E Drake <[e-mail]>]

You can't keep the original, broken LSP around because it no longer has e2e committed resources.  The best you can do is clean it up and try to re-instantiate it on its original path. 

Sent from my iPhone

> -----Original Message-----
> From: Zafar Ali (zali) [mailto:[e-mail]]
> Sent: Wednesday, August 01, 2012 5:48 PM
> To: John E Drake; [e-mail]; 'Ong, Lyndon'; [e-mail]
> Cc: [e-mail]; [e-mail];
> [e-mail]
> Subject: RE: [CCAMP] [Technical Errata Reported] RFC4872 (3304)
> 
> Hi John-
> 
> Please see my response to Adrian's email for the use case for keeping
> the original LSP around during failure.
> 
> Thanks
> 
> Regards ... Zafar
> 
> 
> > -----Original Message-----
> > From: [e-mail] [mailto:[e-mail]] On
> Behalf
> > Of John E Drake
> > Sent: Wednesday, August 01, 2012 7:49 PM
> > To: [e-mail]; 'Ong, Lyndon'; [e-mail]
> > Cc: [e-mail]; [e-mail];
> > [e-mail]
> > Subject: Re: [CCAMP] [Technical Errata Reported] RFC4872 (3304)
> >
> > Is it not the case that the old LSP is broken?  In which case it
> needs
> > to be cleaned up and re-signaled.
> >
> > Sent from my iPhone
> >
> >
> > > -----Original Message-----
> > > From: [e-mail] [mailto:[e-mail]] On
> > > Behalf Of Adrian Farrel
> > > Sent: Wednesday, August 01, 2012 11:02 AM
> > > To: 'Ong, Lyndon'; [e-mail]
> > > Cc: [e-mail]; [e-mail];
> > > [e-mail]
> > > Subject: Re: [CCAMP] [Technical Errata Reported] RFC4872 (3304)
> > >
> > > Hello again,
> > >
> > > > Thank you for the fast evaluation of the errata.  It sounds like
> > > > the
> > > correction that I
> > > > suggested has ended up overspecifying the method to do reversion
> > with
> > > > full rerouting when it is very possible to support a form of
> > > reversion
> > > > that doesn't involve maintaining the old LSP.
> > >
> > > Right, I understand that you want to allow the option of retaining
> > > the old working LSP. Also that you have no intention to remove the
> > > option of removing the old working LSP.
> > >
> > > > From your response I believe that you do agree that it was not
> the
> > > > intent of
> > > the
> > > > original specification text to imply that reversion with full
> > > > rerouting is not
> > > allowed
> > >
> > > Definitely not the intent to imply that reversion with full
> > > rerouting is not allowed.
> > > Does the text say or even imply this?
> > >
> > > > (or to require that the old LSP always be torn down in full
> > > rerouting)
> > >
> > > Also no intention to *require* the old LSP to be torn down.
> > > My view is that the text is fully conformant with that.
> > > I understand that the text does not make an explicit statement of
> > this.
> > >
> > > > so hopefully
> > > > with some more discussion we can determine if there is anything
> > > > that could be done to make that clearer.
> > >
> > > There is, of course, a lot that could be done to make it clearer.
> > > But is there really a need? We discussed the point. We agreed it is
> > > not prohibited in the RFC. Can we not just move on?
> > >
> > > Cheers,
> > > Adrian
> > > > -----Original Message-----
> > > > From: Adrian Farrel [mailto:[e-mail]]
> > > > Sent: Tuesday, July 31, 2012 6:28 PM
> > > > To: [e-mail]
> > > > Cc: [e-mail]; [e-mail];
> > > dimitri.papadimitriou@alcatel-
> > > > lucent.be; [e-mail]; [e-mail];
> > > > [e-mail]; Ong, Lyndon
> > > > Subject: RE: [Technical Errata Reported] RFC4872 (3304)
> > > >
> > > > Hi CCAMP,
> > > >
> > > > I find that this erratum is raised against two sections one of
> > > > which
> > > I
> > > supplied text
> > > > for. If this get contentious, I will call on Stewart to call
> > > consensus
> > > > and
> > > handle the
> > > > Erratum in the system.
> > > >
> > > > In my opinion, this proposal goes further than the intention of
> > > > the authors/WG
> > > in
> > > > publishing 4872.
> > > >
> > > > With regard to the proposed addition to section 11...
> > > > The use of mb4b is already in scope. The existing text says "The
> > > > new LSP resources can be established using the make-before-break
> > > > mechanism," so there is no need to re-state "The new LSP can be
> > > > established without tearing down
> > > the
> > > > old LSP".
> > > >
> > > > I think your concern here is whether the old LSP is ever torn
> down.
> > I
> > > > think
> > > that
> > > > you are worried that if the old LSP is torn down, it might be
> > > > impossible to
> > > perform
> > > > reversion because, after repair, an attempt to revert (also using
> > > > mb4b) might
> > > find
> > > > that key resources have been "stolen" by some other LSP. I don't
> > > > see this as
> > > at all
> > > > different from the issue of the protection LSP itself. That is,
> it
> > is
> > > > of the
> > > nature of
> > > > LSP Rerouting as a protection mechanism that:
> > > > a. protection may fail because of lack of resources b. reversion
> > > > may fail
> > > because
> > > > of lack of resources
> > > >
> > > > *If* reversion is so important, I don't quite see why protection
> > > > is not
> > > important.
> > > > If protection is important then you should be using a proper
> > > > protection mechanism and not waiting for post facto rerouting.
> > > > Furthermore, if you
> > > require
> > > > that the LSP be retained for restoration, why are you not using a
> > > > protection mechanism?
> > > >
> > > > But the general paradigm here is that you are willing to use the
> > best
> > > available LSP
> > > > when it is set up in the first place, the best available LSP when
> > you
> > > > re-route
> > > after
> > > > failure, and the best available LSP when you "revert".
> > > >
> > > > Lastly, it *does* remain an _option_ to retain the failed LSP in
> > > order
> > > > to
> > > switch
> > > > back. Nothing in the old text precludes that, although I
> > > > understand that there
> > > is
> > > > an implication that it might be expected to be torn down.
> > > >
> > > > So I conclude that the proposed addition to section 12 is not
> what
> > > the
> > > > authors/WG intended.
> > > >
> > > > We should discuss further.
> > > >
> > > > Adrian
> > > >
> > > > > -----Original Message-----
> > > > > From: RFC Errata System [mailto:[e-mail]]
> > > > > Sent: 31 July 2012 17:39
> > > > > To: [e-mail]; [e-mail];
> > > > > dimitri.papadimitriou@alcatel- lucent.be; [e-mail];
> > > > > [e-mail]; [e-mail]; [e-mail]
> > > > > Cc: [e-mail]; [e-mail]; [e-mail]
> > > > > Subject: [Technical Errata Reported] RFC4872 (3304)
> > > > >
> > > > >
> > > > > The following errata report has been submitted for RFC4872,
> > > > > "RSVP-
> > > TE
> > > > > Extensions in Support of End-to-End Generalized Multi-Protocol
> > > Label
> > > > > Switching (GMPLS) Recovery".
> > > > >
> > > > > --------------------------------------
> > > > > You may review the report below and at:
> > > > > http://www.rfc-editor.org/errata_search.php?rfc=4872&eid=3304
> > > > >
> > > > > --------------------------------------
> > > > > Type: Technical
> > > > > Reported by: Lyndon Ong <[e-mail]>
> > > > >
> > > > > Section: 11 & 12
> > > > >
> > > > > Original Text
> > > > > -------------
> > > > > Section 11 says:
> > > > >
> > > > >
> > > > >    (Full) LSP rerouting will be initiated by the head-end node
> > that
> > > has
> > > > >    either detected the LSP failure or received a Notify message
> > > and/or a
> > > > >    PathErr message with the new error code/sub-code "Notify
> > > Error/LSP
> > > > >    Locally Failed" for this LSP.  The new LSP resources can be
> > > > >    established using the make-before-break mechanism, where the
> > new
> > > LSP
> > > > >    is set up before the old LSP is torn down.  This is done by
> > > using the
> > > > >    mechanisms of the SESSION_ATTRIBUTE object and the Shared-
> > > Explicit
> > > > >    (SE) reservation style (see [RFC3209]).  Both the new and
> old
> > > LSPs
> > > > >    can share resources at common nodes.
> > > > >
> > > > > Section 12 says:
> > > > >
> > > > >    [No text on reversion for (full) LSP Rerouting.]
> > > > >
> > > > > Corrected Text
> > > > > --------------
> > > > > Section 11 should say:
> > > > >
> > > > >
> > > > >    (Full) LSP rerouting will be initiated by the head-end node
> > that
> > > has
> > > > >    either detected the LSP failure or received a Notify message
> > > and/or a
> > > > >    PathErr message with the new error code/sub-code "Notify
> > > Error/LSP
> > > > >    Locally Failed" for this LSP.  The new LSP resources can be
> > > > >    established using the make-before-break mechanism, where the
> > new
> > > LSP
> > > > >    is set up before the old LSP is torn down.  This is done by
> > > using the
> > > > >    mechanisms of the SESSION_ATTRIBUTE object and the Shared-
> > > Explicit
> > > > >    (SE) reservation style (see [RFC3209]).  Both the new and
> old
> > > LSPs
> > > > >    can share resources at common nodes.  The new LSP can be
> > > established
> > > > >    without tearing down the old LSP in case of reversion (see
> > > section 12).
> > > > >
> > > > > Section 12 should say:
> > > > >
> > > > >    For "(full) LSP Rerouting", reversion implies that the old
> > > > > LSP
> > > is not
> > > > >    torn down by the head-end node after the new LSP is
> > established.
> > > For
> > > > >    reversion, the head-end node re-activates the old LSP after
> > this
> > > has
> > > > >    recovered.
> > > > >
> > > > >
> > > > >
> > > > > Notes
> > > > > -----
> > > > > Current text in RFC 4872 describes reversion in the cases of
> 1+1
> > > > > bidirectional Protection, 1:N Protection with Extra Traffic and
> > > > > Rerouting Without Extra
> > > > Traffic,
> > > > > however it has no description of reversion with (Full) LSP
> > > Rerouting.
> > > > > For (full) LSP Rerouting, the description in Section 11 instead
> > > > > implies that
> > > > the old
> > > > > LSP is torn down. This has led to some confusion as to whether
> > > > > reversion with
> > > > > (full) LSP Rerouting is allowed or not allowed by the RFC. We
> > > > > believe this was
> > > > not
> > > > > intentional. The additions would make it clear that reversion
> > > > > can
> > > be
> > > > > supported with (Full) LSP Rerouting.
> > > > >
> > > > > Instructions:
> > > > > -------------
> > > > > This errata is currently posted as "Reported". If necessary,
> > please
> > > > > use "Reply All" to discuss whether it should be verified or
> > > rejected.
> > > > > When a decision is reached, the verifying party (IESG) can log
> > > > > in
> > > to
> > > > > change the status and edit the report, if necessary.
> > > > >
> > > > > --------------------------------------
> > > > > RFC4872 (draft-ietf-ccamp-gmpls-recovery-e2e-signaling-04)
> > > > > --------------------------------------
> > > > > Title               : RSVP-TE Extensions in Support of End-to-
> End
> > > Generalized
> > > > Multi-
> > > > > Protocol Label Switching (GMPLS) Recovery
> > > > > Publication Date    : May 2007
> > > > > Author(s)           : J.P. Lang, Ed., Y. Rekhter, Ed., D.
> > > Papadimitriou, Ed.
> > > > > Category            : PROPOSED STANDARD
> > > > > Source              : Common Control and Measurement Plane
> > > > > Area                : Routing
> > > > > Stream              : IETF
> > > > > Verifying Party     : IESG
> > >
> > > _______________________________________________
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> > > https://www.ietf.org/mailman/listinfo/ccamp
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