Subject: label generation algorithms

From: "Sylvia Sugar" <[email-masked]>
Date: Sat, 26 Apr 2003 19:15:56 +0000

Hello friends,

As usual I have come up with the dumbest of query.

:( I would love it if someone could take time to answer the same.

Is there anyway one can 'pinpoint' the end of an LSP without allocating the 
end point, a 'certain identifier'?

-SylviaXO

_________________________________________________________________
MSN 8 with e-mail virus protection service: 2 months FREE* 
http://join.msn.com/?page=features/virus

---

From: David Charlap <[email-masked]>
Date: Mon, 28 Apr 2003 11:24:13 -0400

Sylvia Sugar wrote:
> 
> Is there anyway one can 'pinpoint' the end of an LSP without allocating 
> the end point, a 'certain identifier'?

Well, if you trace the LSP and find a node that does a label-pop, then 
that node is the end of that LSP.  Of course, there could be lower-level 
labels that will cause the packet to be label-switched to another 
router, but that label would correspond to a different LSP.

When RSVP-TE is used for signaling, each LSP has a "tunnel endpoint 
address" which identifies the IP address where the LSP ends.

When LDP is used for signaling, it's trickier.  The FEC will tell you 
the address where the LSP is supposed to end, but if one or more nodes 
along the path to that address isn't participating in LDP (and 
downstream unsolicited label allocation is used), the LSP will end at an 
intermediate node somewhere.

If you are looking for some kind of magic bullet to let you look at any 
node along any arbitrary LSP and say "the endpoint is w.x.y.z", I don't 
think there exists one.

-- David

---

From: "Alok Dube" <[email-masked]>
Date: Tue, 29 Apr 2003 19:45:04 +0530 (IST)

Hi David,Sylvia/All,

> that node is the end of that LSP.  Of course, there could be
> lower-level  labels that will cause the packet to be label-switched to
> another  router, but that label would correspond to a different LSP.
>
> downstream unsolicited label allocation is used), the LSP will end at
> an  intermediate node somewhere.
>
>  node along any arbitrary LSP and say "the endpoint is w.x.y.z", I
> don't  think there exists one.

this thread got me thinking...

if I may ask,

does this imply that to achieve the same:
1. either the end point be uniquely identified and propoated? (eg:PE:VRF
should be uniquely identified) in some format so that every node can reach
it?2. if 1 is true, this information has to be there with both P and Pe
routers so that they know "what sending to a particular PE:VRF" means?
in the sense every node has to know what this "PE:VRF" identifier is?

it could be an IP, it could be something else...but that protocol running
on the P needs to know and understand the meaning of this too.
another question I have is:

what if i use draft-kompella-ppvpn kind of signalling (BGP passing the
labels and stuff) and take away the P routers? all nodes are PE  and thats
it, we have them in full mesh and thats it...? how does it work then?
Would appreciate if someone could clarify.

-rgds
Alok