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

["Zafar Ali (zali)" <[e-mail]>]

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
> >
> > _______________________________________________
> > CCAMP mailing list
> > [e-mail]
> > https://www.ietf.org/mailman/listinfo/ccamp
> _______________________________________________
> CCAMP mailing list
> [e-mail]
> https://www.ietf.org/mailman/listinfo/ccamp