Subject: Defining FEC types at the ingress...

From: "Kannan J" <[email-masked]>
Date: Mon, 23 Jul 2001 14:39:49 +0000

Hi

The MPLS Architecture states that different types of
FECs can be defined at an ingress to allow for both
coarse grained and fine grained forwarding granularity.

At present LDP supports only two types of FEC
elements -  the host address and address prefix types.
So even though we may define other types of FEC elements
(e.g based on port no etc ) at the ingress it will not
make sense to the LSRs downstream to the ingress as label
exchange happens based only on the destination address
prefix ( coarse forwarding granularity).

However it does seem possible to achieve fine forwarding
granularity through static configuration or via SNMP. For
example the FTN MIB does have a provision to support FEC
elements other than what LDP provides namely source address type ,  port no 
etc and then map them to preconfigured LSPs thereby
having the capability to map specific flows to specific LSPs.

My question is :  should implementors of the mpls stack
assume that only those FEC types as defined in the LDP spec be
used or can they assume that there can be different types of FEC
elements as described above ?    And if the latter how will it
help as unless LDP is extended to support new FEC types such as source
address or port no ,  there will not be any real benefit.

I would appreciate your comments/clarifications on this.

Thanks
Kannan

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From: "Thomas D. Nadeau" <[email-masked]>
Date: Mon, 23 Jul 2001 11:23:00 -0400

At 02:39 PM 7/23/2001 +0000, Kannan J wrote:

>elements other than what LDP provides namely source address type ,  port 
>no etc and then map them to preconfigured LSPs thereby

         What if you are not only using LDP for FEC-NHLFE assignments?
For example, CLI->tunnel head or RSVP?

         --Tom

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From: "chetan kumar s" <[email-masked]>
Date: Tue, 24 Jul 2001 08:59:12 +0530 (IST)

Hi,

<snip>
> For example, CLI->tunnel head or RSVP?

OR CR-LDP

Thanks
Chetan S