Subject: RE: LSP Failure Notification

From: "Dekany, Steven" <[email-masked]>
Date: Fri, 20 Apr 2001 10:28:04 -0400

Thank you Bora; 

and thank you Haoxin and Giles.

Yes, best effort is kind of the expected "default" behavior. I just wonder
that when we say that the IGP route will become the "next best route" what
happens to my SLA with the customer - assuming that there is one in place? I
guess the underlying assumption is that I use MPLS in the core because I
want to give something better than best effort service to my customer. Now
that my LSP is broken and that I cannot setup another one - at least for
while, in theory - if I use best effort only, I have basically violated my
service level agreement with my customer. Should I not notify him somehow?
Or this REALLY VERY IMPLEMENTATION SPECIFIC - read, either private
information, or policy dependent?

Another theoretical question - how significant is usually the time delay
between IGP's convergence and by the time RSVP-TE has found a new LSP? If
that is a relatively short time, I may not care, but if it takes a few tens
of seconds or minutes, and I have a relatively high speed link to the LER,
it may flood my network with unwanted IP traffic real badly too, causing
another cascading TE problem for me potentially in the core.

Along the same line, if I have certain traffic parameter requirements for my
LSP - as required by my SLA - it is entirely possible that RSVP-TE may not
find a suitable LSP and comes back with PathErr. Do I still fall back to
forward best effort? 

I wonder if there is any practical experience with this question, or IP best
effort is the generally implemented default.

Thank you again to all again, who kindly responded,

Best Regards,

Steven 

-----Original Message-----
From: Bora Akyol [mailto:[email-masked]]
Sent: Friday, April 20, 2001 9:00 AM
To: Dekany, Steven
Cc: [email-masked]
Subject: Re: LSP Failure Notification

The tunnels are established using IGP reachability information. When the
tunnel goes away, IGP route will become the next best route and traffic
will be traveling via IP.

This may take a while, but until the head end realizes that the tunnel is
down, there really is not much you can do. The packets will fall on the
ground.

I believe G-MPLS defines a failure notification mechanism.

Bora

On Fri, 20 Apr 2001, Dekany, Steven wrote:

> Greetings;
> 
> I am looking for help, with the following:
> 
> Assume I have an MPLS Service Provider network, running RSVP-TE as a
> signaling protocol. Customer sites are connected to my network via various
> IP only links - no MPLS.   Upon a LSP link failure in my core - assume
that
> I have exhausted all back-up, re-route etc., options and my LSP tunnel is
> still down - what happens to my incoming IP traffic at the ingress LER? Is
> there an ICMP message generated back to IP Source with "Destination
> Unreachable? , or an SNMP Trap, or both? Or something else? 
> 
> (Or is this a dumb question, because I have not read the relevant
draft...)
> 
> Any help or pointers would be greatly appreciated.
> 
> Thanks in advance,
> 
> 
> Steven 
>

---

From: Ramesh Bhandari <[email-masked]>
Date: Fri, 20 Apr 2001 10:59:54 -0400

Steven,

Have you considered phyiscally-disjoint pair of LSP's in the solution,
with one LSP as a backup so that if the primary path fails the affected
traffic can flow on the backup?

Ramesh