Subject: Re: About LSP Stitching

From: Amit 70405 <[email-masked]>
Date: Tue, 12 Apr 2005 15:36:16 +0800

Hi Arthi,
   Thanks for replying.

   Below are the two main assumptions on which my query is based.
   Plz correct me if I am wrong.
   1. E2e LSP & LSP segment are two independant LSP's.
   2. TE-Link is a kind of abstraction.
      User of TE-Link should not know about the implementation details of the TE-Link.

   Whether it is a FA or a LSP segment as a TE-Link, an LSP setting up over these TE-Link should not be aware of the TE-Link setup details(whether its a FA or a LSP segment or a Physical Interface or others).

   So if we go by this, the below example which i gave holds true.
 
   Plz let me know your view on this.
Thanks and regards,
Amit.

----- Original Message -----
From: Arthi Ayyangar <[email-masked]>
Date: Saturday, April 9, 2005 4:22 am
Subject: Re: About LSP Stiching

> Amit,
> 
> >  There is no way for LSP segment head node, to identify that a
> > Outif selected is a LSP Segment for setting up E2e LSP.
> ---> What do you mean ? Why would the head-end of an LSP segment 
> not know
> that selected nexthop is the LSP segment ? It is the head-end of 
> the LSP
> segment selecting what you call Outif.
> 
> 
> >  That is Some extension will be needed to RSVP that will allow RSVP
> > message(for E2e LSP) processing at LSP segment head node to be 
> processed> according to the Sticthing needs.
> ------> I don't think there is any need for any more 
> extensions..see my
> explanation above and below.
> 
> 
> >  For Eg: LSP1-2 is an E2e LSP setup over an LSP segment LSPA-B.
> >
> >  1-----A--D---E--B-----2
> >
> >  Now if A gets the Path message for LSP1-2, and A selects LSP
>        segment LSPA-B as outif.
> >  Then how does RSVP(at Node A) identify that the outif selected is
>        a LSP segment?
> -------> A is doing nexthop (what you call outif) selection, A is the
> head-end of LSP segment. A knows that nexthop is an LSP segment.
> 
> 
> >  Also when A receives Resv for LSP1-2(from B), how can it ignore
> >     Label in it.
> >  There should be a way to determine at node A, that a LSP segment
> > is in use.
> -----> A chose to stitch the e2e LSP to the LSP segment in the 
> first place.
> 
> thanks,
> -arthi
> 
> 
> 
> >  One possible way could be that Resv message for LSP1-2 should be
> > sent(by B) with some special Label value.
> >  This Label value should indicate the node A that the Resv is
> > received for a TE-Link(of type LSP Segment).
> >  This will help node A to ignore Label value in Resv msg for E2e
> > Lsp LSP1-2.
> 
>