Subject: RE: LSP ID

From: Marc Lewis <[email-masked]>
Date: Tue, 24 Apr 2001 08:25:19 -0700

David Charlap wrote:

> [...]  It is perfectly legal for
> routers to use an extended tunnel ID of zero ("don't care") - making it
> possible to share resources with LSPs that originate from multiple
> points.  Because of this, you really need the full 5-tuple (the above
> parameters plus extended tunnel ID) in order to uniquely identify an LSP.

This relates to a question I have about the SENDER_TEMPLATE object
(specifically, the LSP_TUNNEL variety).  The draft says the IP address
is for "a" sender node.  Does this mean "the" sender node?  i.e. the
ingress of the tunnel?  

I assumed it did, and that due to the point you make above, that the 
SENDER_TEMPLATE was therefore the proper place from which to derive the
ingress IP address.  But I'm sure I've seen traces of RSVP-TE traffic
where transit LSRs put their own IP addresses in the SENDER_TEMPLATE
instead of passing it on unmodified.  (those same transit LSRs did,
as I recall, put the ingress address in the ExtTunnelID of the
SESSION object)

---

From: David Charlap <[email-masked]>
Date: Tue, 24 Apr 2001 12:12:33 -0400

Marc Lewis wrote:
> (specifically, the LSP_TUNNEL variety).  The draft says the IP
> address is for "a" sender node.  Does this mean "the" sender node?
> i.e. the ingress of the tunnel?

That would be correct.

> SENDER_TEMPLATE was therefore the proper place from which to derive
> the ingress IP address.

Yes.

> But I'm sure I've seen traces of RSVP-TE traffic where transit
> LSRs put their own IP addresses in the SENDER_TEMPLATE instead of
> passing it on unmodified.  (those same transit LSRs did, as I
> recall, put the ingress address in the ExtTunnelID of the SESSION
> object)

This would be a broken implementation.  Transit LSRs should be putting
their own addresses in the HOP objects.  SESSION, SENDER_TEMPLATE and
FILTER_SPEC (the objects that define endpoints) should propagate
unaltered.

-- David