Subject: LSP Merge Issue(Using RSVP)

From: Neetu Gupta <[email-masked]>
Date: Tue, 23 May 2000 09:58:15 +0530

Hello,
    This topic has been discussed before. But, My query is bit different
from the one previously discussed:

Suppose we have the following setup:

    A
        \
          \
           C===D===E
          /
         /
      B

Suppose that A sends Path message specifying tunnel endpoint address E.
Thus LSP 1  is created from A to E.
Now Suppose another Path Message from B and destined for E comes.

Suppose , it is configured that LSP merging at C is possible
- Both Path messages have "Merge permitted" flag in Session
  Attributes set
- Both Path Messages requesting for same Class of Service

When the Path Message from B reaches E, E finds that there is already an
LSP for the session, and since it knows that C can merge the LSPs, it'll
assign a new label with the resources set for this LSP equal to LUB of
both the flowspecs(if style is Shared Explicit) or sum of both the
flowspecs(if style is FixedFilter) and delete the label of LSP1
- E sends Resv Message to D with Flow Descriptor containing merged
flowspec and two Filterspec objects (one for A and one for B) and same
label to both .

- D assigns a new incoming label and remove the old label of LSP1 and
modify the flowspec with the one coming in the Resv Message and sends
the Resv Message to C.  This Resv also specifies identical label values
for A and B, and flowdescriptor identical to the one coming in the Resv
Message from E.
- Since, C is the merge point.  It assigns a new incoming label for B.
Thus at C, there will be two incoming labels , one for A and one for B.
  It then sends Resv to B.

Is this correct? Can we Merge the LSPs as specified above?
Please clarify
-neetu

---

From: Rajiv Papneja <[email-masked]>
Date: Wed, 24 May 2000 10:30:42 -0400 (EDT)

Hi there,

Please see my comments below

> flowspec and two Filterspec objects (one for A and one for B) and same

COMMENTS : If the style is Shared Explicit then the resulting filterspec
is the union of the original filterspecs and the resulting flowspec is
the largest of the flow spec. However, if  LSR B requests for higher
bandwidth and LSR A requests for tighter delay, in this case service
specific merging is would be required. Then, as you suggested, the
resulting flowspec is at least as large as LUB ( least Union Bound). 

> Is this correct? Can we Merge the LSPs as specified above?
take care 

Rajiv 

AIL, GMU