The MPLS WG Archive

[manikantan <manis@future.futsoft.com>]

Hello Thomas

#
#>Hence my doubts are:
#>1) Should the Tunnel Instance be always treated as "0" when CRLSP tunnels are
#>made?
#
#         Yes.

Mani> Thanks for the clarification.

#
#>2) Is it that the LSPID-TLV has Action flag to indicate modification of the
#>Tunnel, it is not required to identify instances in CRLSP? Reason : The usage
#>of instance (When the instance value is mapped to the LSP_ID of the Sender
#>Template object) is sending indication for reroutes in RSVP?.
#
#         So what are you advocating here?
#

Mani> Sorry for not being clear with the above question. I have raised the
above question when I try to compare RSVP-TE and CRLSP and look for the 
differences, issues for interworking if any etc.,

The concept of instances of Tunnels has been explained as follows
in the TE MIB <draft-03.txt - 10 March 2000>

  "Uniquely identifies an instance of a tunnel. It 
   is useful to identify multiple instances of
   tunnels for the purposes of backup and parallel
   tunnels."

When I think to apply the instance value as part of RSVP message and 
transmit downstream, the LSP ID in the sender Template object fits 
perfectly.

(Another question, IS this the way it is to be done?)

The usage of LSP ID is very helpful in the "make-before-break" situation
for a RSVP Tunnel re-route (i.e., tunnel modification). (Reference Section 
4.6.4 Reroute procedure in rsvp-mpls-tunnel-05.txt draft).

As the usage for the reroute can be done very well with the concept of instances,
i.e., tunnel instance id, (Scope for the utilization for backup and parallel tunnels not 
available, or I would have missed out), I attempt to apply the same
in the CRLSP case too.. i.e. instances -- used for re-routing. 

Hence my question is, since the CRLSP Draft - LSPID-TLV has the action flag
for modification ( reroutes), is it that the instances are not required or reroutes?

Now my understanding is that it is not required and the instance id will
be always the same and equals zero ( with the answer to my first question is "0". )

Hope I am clear now.

thanks in advance
with best regards
mani