The MPLS WG Archive

[Gopalkrishna Panicker <gopanicker@yahoo.com>]

Hello,

Consider the following topology


   A-----------B----------C

Let us say
1. we are using make-before-break and therefore
   using SE style.
2. LSP1 with Sender1 has been signalled with a  
   bandwidth of 20 units. A is the ingress and C is
   the egress.

 Now A decides to reduce the bandwidth to 10 units.
 A ceates a new sender template (Sender2) and 
 Tspec. A then sends the path message towards C. 

 After receiving the path message, C computes the
 bandwidth to be allocated. Since SE style is being 
 used, the merged flowspec sent in the resv message
 from C to B will  continue to say a bandwidth of 
 20 units. 
 The only reason the resv  makes it back
 to A is because of the new filterspec (Sender2).

 I assuming this is correct.

  Now A issues a path tear for sender1. B will
  delete the path state associated with sender1. 
  B will also delete the corresponding filter spec
  from the resv state. 
 
  Now to my question. How does B know that it has
  to delete the 10 units of bandwidth reservation ?
  
  If my understanding is correct, the resv message
  from C had carried a merged flowspec and set of
  filterspecs (Sender1, Sender2). How does B 
  determine the orginal flowspec associated with
  the filterspec (in this case Sender1) ?
  
  Should B on rely on the tspec stored in the PSB ? 


 Obviously I am missing something.

 Thanks

 Cheers
 Gopal




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