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

Lyndon,

That all depends on what you mean by "in".

A

> -----Original Message-----
> From: Ong, Lyndon [mailto:Lyong@ciena.com]
> Sent: 02 August 2012 23:18
> To: adrian@olddog.co.uk; 'Zafar Ali (zali)'; ccamp@ietf.org
> Cc: jplang@ieee.org; dimitri.papadimitriou@alcatel-lucent.be;
> dbrungard@att.com
> Subject: RE: [CCAMP] [Technical Errata Reported] RFC4872 (3304)
> 
> Hi Adrian,
> 
> I'm glad that you say that this (LSP rerouting with reversion) is possible
within the
> existing text, hopefully we can all accept this as conclusive.
> Probably this issue would have been clearer if there was a formal definition
of
> "implies" in RFC 2119!
> 
> 
> Cheers,
> 
> Lyndon
> 
> -----Original Message-----
> From: ccamp-bounces@ietf.org [mailto:ccamp-bounces@ietf.org] On Behalf Of
> Adrian Farrel
> Sent: Thursday, August 02, 2012 2:33 PM
> To: 'Zafar Ali (zali)'; ccamp@ietf.org
> Cc: jplang@ieee.org; dimitri.papadimitriou@alcatel-lucent.be;
> dbrungard@att.com
> Subject: Re: [CCAMP] [Technical Errata Reported] RFC4872 (3304)
> 
> Oh dear.
> 
> First, let me re-assert...
> 
> The discussion of whether you might want to do it (that we are having now) is
> orthogonal to whether it is possible. I have no issue that it is possible, and
I don't
> think any changes are needed to any documents to enable it or to say that it
is
> possible.
> 
> 
> Now to your details...
> 
> > 1. We are at time t0.
> > 2. Working LSP is setup on THE nominal path (P) with setup/ holder
> > priority (s,h). For simplicity assume P is explicitly configured by SP.
> > 3. At time t1 > t0, a resource, say link L fails, along the nominal Path
(P).
> > 4. Ingress tears down working LSP.
> 
> Better not?
> You do this and you are not doing mb4b.
> 
> > 5. A restore LSP or protecting LSP starts to carry traffic.
> > 6. Link L comes back up at t2 > t1.
> > 7. Some other LSP(s) with setup/ hold priority better than working LSP
> > setup/holder priority (s,h) claims resources from L.
> > 8. Nominal Path P is no longer available for working LSP and this is
> > the only Path SP wants the working LSP to take.
> 
> If the setup/holding priorities are higher, then these new LSPs would take the
> resources in any case.
> Probably, the interesting case for you is that the new LSPs have identical
(s,h).
> 
> > 9. Reversion cannot be applied as working LSP stays down.
> 
> Correct.
> 
> Now consider...
> 
> 1a. We are at time t0.
> 2a. Some other LSP(s) with setup/ hold priority better than working LSP
> setup/holder priority (s,h) claims resources from L.
> 3a. Working LSP is attempted on THE nominal path (P) with setup/ holder
priority
> (s,h).
> 4a. Nominal Path P is no longer available for working LSP and this is the only
Path
> SP wants the working LSP to take.
> 5a. Service cannot be set up as working LSP stays down.
> 
> My point being: when you decided that you did not want to use protection, you
> signed up to a particular service level. Of course you would like to apply
> reversion, but it is not essential.
> 
> Alternatively, when you decided to allow other LSPs to be able to use "your"
> network resources, you signed up to a way of operating your network where that
> can happen.
> 
> A
> 
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