Subject: RE: draft-meyer-soft-preemption-00.txt

From: "Ferrell, William" <[email-masked]>
Date: Tue, 18 Mar 2003 15:41:17 -0500

Hmmm.. 
This sounds like a real vulnerabilty. Just how exploitable it is may be
worth further investigation.
Will

-----Original Message-----
From: Curtis Villamizar [mailto:[email-masked]]
Sent: Tuesday, March 18, 2003 12:35 PM
To: Adrian Farrel
Cc: [email-masked]; Jean Philippe Vasseur; George Swallow;
[email-masked]; [email-masked]; [email-masked]; [email-masked]'
Subject: Re: draft-meyer-soft-preemption-00.txt 

In message <[email-masked]>, "Adrian Farrel"
writes:
> 
> Are you sure there are no implementations out there that will tear down =
> the LSP because of an unrecognized flag in the RRO? :-)
> 
> Adrian

Based on our experience with the local-protect bits, there is an
implementation out there that we know will tear down the LSP because
of an unrecognized flag in the RRO but that same implementation will
send a path-err when it doesn't recongnize the capability request bits
in the session attributes flags so soft-preempt will be disabled.

Curtis

---

From: Curtis Villamizar <[email-masked]>
Date: Tue, 18 Mar 2003 15:51:54 -0500

In message <561621C69F17D511A3A20050047340EC01AAF627@VCMD-NT1>, "Ferrell, Willi
> worth further investigation.

This is just a matter of disabling a feature.  In the case of
local-protect, interoperability is acheived by not setting the
local-protect bits.  It is also an implementation that pre-dates the
current fast-reroute draft and this behaviour wrt at least the
local-protect bits is going away.

At worst with the current situation and lacking a work around fast
reroute protection would be defeated.  Considering that this is
pre-standards (deployed though) for FRR, some incompatibilities
between vendors can bw expected as implementations converge on a
common specification.

With soft-preempt, at worst an LSP which is being preempted gets torn
down so in effect soft preempt doesn't work with a particular midpoint
LSR that doesn't support it.

Not much of an exploit in either case.

Curtis