Subject: Static LSPs (Does MPLS Require L3 Routing Table ?)

From: "Dave Danenberg" <[email-masked]>
Date: Thu, 19 Apr 2001 13:03:04 -0400

Juha,

2 weeks back on another MPLS email thread, folks were discussing how
popular statically configured LSPs (MPLS PVCs) might be. This was with
respect to detection of data-plane faults if there is no MPLS
control-plane. Within the email thread, folks said that although the
MPLS equipment will support static LSPs, they were not aware of plans
for static LSP deployments. It seems from your response below, you
believe MPLS PVCs will be popular because operators will not want
customers to apply signaling to their networks. Do I understand you
correctly? If so, what mechanisms would you use to detect data-plane
faults within networks configured with MPLS PVCs?

--Dave

-----Original Message-----
From: Juha Heinanen [mailto:[email-masked]]
Sent: Thursday, April 19, 2001 12:17 PM
To: [email-masked]
Cc: [email-masked]; [email-masked]
Subject: Re: Does MPLS Require L3 Routing Table ? 

Eric Rosen writes:

 >    An LSR receiving a Label Mapping message from a downstream LSR for
a
 >    Prefix or Host Address FEC Element should not use the label for
 >    forwarding unless its routing table contains an entry that exactly
 >    matches the FEC Element.
 > 
 > So one can't really do things the way you suggest.  

"should not" is not the same as "must not".  i was just trying to point
out what CAN be done and not that it would be a good idea to do so.

 > Given a  pre-existing LSP connecting  two CEs, it  might well make
sense to
 > have a procedure  for each to discover  who is at the other  end.
The prior
 > question  here  would  be  whether  there  is real  value  in  having
these
 > pre-existing LSPs connecting the two CEs.

there is a huge installed base of frame relay that is almost 100% based
on the pvc paradigm.  the fact is that operators don't like the idea of
customers signaling dynamically frame relay svcs in their networks and
the same will hold for mpls lsps.

 > I think what people have been objecting to is the suggestion (now
apparently
 > disavowed)  that such a  procedure somehow  eliminates the  need to
have L3
 > routing in  the core.   That's what made  it seems  like there must
be some
 > MPOA-like stuff hiding beneath the surface. 

the soft permanent lsps are setup using l3 routing protocol.  there is
no mpsl like stuff anywhere.  frame pvcs connecting routers have been
used years before mpoa appeared.

-- juha