Subject: RE:

From: "sumit singh" <[email-masked]>
Date: 2 Jun 2003 06:21:10 -0000

Hello,

I have some questions on RFC 3031, MPLS Architecture.

Section 3.12 says
    "If the FTN maps a particular label to a set of NHLFEs that 
contains
    more than one element, exactly one element of the set must be 
chosen
    before the packet is forwarded.  The procedures for choosing 
an
    element from the set are beyond the scope of this 
document.Having
    the FTN map a label to a set containing more than one NHLFE 
may be
    useful if, e.g., it is desired to do load balancing over 
multiple
    equal-cost paths."

1. Here actually we should be talking about the FEC to  NHLFE 
mapping rather than Label to NHLFE mapping. Isn't that correct?

2. Have these procedures to identify one of the multiple entries 
been defined as of now? If yes, wonder if I could get some 
pointers for them.

3. Are there other scenarios also wherein it's useful to map an 
FEC to multiple NHLFEs?

Would greatly appreciate any response.

Regards,
Sumit

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---

From: "Sumit Garg" <[email-masked]>
Date: Mon, 2 Jun 2003 13:20:00 -0400

> mapping rather than Label to NHLFE mapping. Isn't that correct?

FTN = FEC to NHLFE
ILM = Incoming Label Map (Label to NHLFE)

Yes, you are correct

> been defined as of now? If yes, wonder if I could get some

No, nothing has been standardised (atleast I'm not aware).  This where
vendor value add comes in.

> 3. Are there other scenarios also wherein it's useful to map an

Fast re-route/ backup LSPs.  Specialized handling where one may want to
send packets belonging to a special category (incoming i/f, src IP, dest
port or other such information) on a special LSP i.e. the FEC is now
more than just the dest IP, it is augmented with more information.

Cheers
-- Sumit Garg