Subject: RE: [PWE3] MPLS PID

From: "Thomas D. Nadeau" <[email-masked]>
Date: Wed, 26 Mar 2003 15:16:14 -0500

At 06:52 PM 3/25/2003 -0500, Andrew G. Malis wrote:
>Shahram and Alia both make excellent points:
>
>At 3/25/2003 02:18 PM -0800, Shahram Davari wrote:
>> >1.  Dealing with ECMP behavior
>> >2.  Inband OAM flows
>> >3.  Identifying flows for netmanagement applications.
>>
>>I don't think any of them justifies adding PID.
>>
>>1) ECMP could use only label hashing and not hash IP header.
>>2) OAM flows could use IPv4/V6 null or MPLS Alert label
>>3) Netmanagment could identify the flow at the ingress.
>
>At 3/25/2003 06:15 PM -0500, Alia Atlas wrote:
>>How does requiring a PID in the PWE3 L2 control word solve or handle the 
>>case where a control word is not mandatory?
>>
>>There are pseudo-wires, such as ethernet, where a control word is not 
>>mandatory.  This would imply that the first nibble (which would be 
>>identified as the suggested PID) would be that from the ethernet frame.
>
>We're going to have to change the PWE3 drafts to require the control word, 
>and change both the SONET/SDH and some of the ATM encapsulations, to 
>support a hack.

         Andy,

         Some people believe that the non-use of the control
word is a hack/micro-optimization that should be removed.

>If you REALLY want multi-protocol identification, then have the MPLS WG 
>put a REAL multiprotocol identifier, a la RFC 2427 or 2684, between the 
>labels and the payload.  See, for example, 
>draft-moreels-multiproto-mpls-00.txt for a much more general (and useful) 
>method than just a four-bit hack.  And sorry for the cross-post, but this 
>really does affect both WGs.

         Do you think that it is realistic to go back and change
the MPLS header format at this point in the game?

         --Tom

>Cheers,
>Andy
>
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