Subject: FW: Traffic Engineering TLV

From: "Naidu, Venkata" <[email-masked]>
Date: Tue, 14 Aug 2001 10:36:30 -0400

Prabhu:

->             Can anyone please tell me what are these 8 
-> priority levels and what for these 
->             used ? 

  There are no set of semantics for each priority level. 
  The different levels provide an ordering that can be 
  used to determine preemption during the establishment 
  of LSPs. They can also be used by an implementation 
  as a means of ordering LSP computation and setup.

  How to use these priority levels? Look at:
  CR-LDP draft-ietf-mpls-cr-ldp-05.txt and
  RSVP-TE draft-ietf-mpls-rsvp-lsp-tunnel-08.txt

-> why we need this. 

  The need for priority levels is specified in
  RFC 2702. There is a consensus of eight protocols 
  being sufficient.  

  In Dan's terms...

  "The priority attribute defines the relative importance of traffic
   trunks.  If a constraint-based routing framework is used with MPLS,
   then priorities become very important because they can be used to
   determine the order in which path selection is done for traffic
   trunks at connection establishment and under fault scenarios.

   Priorities are also important in implementations  permitting
   preemption because they can be used to impose a partial order on the
   set of traffic trunks according to which preemptive policies can be
   actualized."

--Venkata Naidu