Re: New draft on Extra class LSP

["Adrian Farrel" <adrian@olddog.co.uk>]

I agree with Dimitri here.

There is no reason to assume that (the resources for) a protection LSP
should not pre-empted by some other LSP. That is the nature of pre-emption
and it is a Good Thing (TM).

Just as the working LSP might itself be pre-empted, so might the protection
LSP.

One might invent all sorts of schemes to help manage this (such as making
protection LSPs operate at a higher priority than working LSPs), but this is
a network operator's choice (or the subject of a BCP). No new protocol would
appear to be necessary to manage this.

Adrian

----- Original Message ----- 
From: <Dimitri.Papadimitriou@alcatel.be>

> > In the latter case, however, the only way any traffic could use the
> > reserved resources would be for one to setup a low-priority,
pre-emptible
> > LSP using those resources, with the distinction that these particular
> > low-priority LSPs are not subject to pre-emption unless a working
> > LSP that needs to use those reserved resources fails (This what
> > Shiomoto-san more accurately calls "extra-LSP".)
>
> the point is to have a network wide homogeneous allocation
> of resources, starting to have allocation based on the
> reason why the lower priority lsp can be preempted leads you
> to the issue of how many of such conditions can we have
> in a network ? or do you plan to start defining one class
> of lsp and priority per such event ? the idea behind the
> "re-use" of these preemptible resources is to abstract its
> complexity not to spread it network wide - this while what
> we have today works perfectly -