Re: [mpls] Poll 1: ISD and PSD in the MNA Framework

[Tianran Zhou <[e-mail]>]

Hi Adrian,

" It was Tianran, I think, who questioned the need for in-stack data, but I agree with him that it seems reasonable for the Framework to describe it unless we can come up with a killer reason why it should not be used. "

Yes, I questioned the need for ISD.
And in my opinion, without a killer reason,  the Framework should not include ISD.

Best,
Tianran
-----Original Message-----
From: mpls [mailto:[e-mail]] On Behalf Of Adrian Farrel
Sent: Thursday, June 9, 2022 5:03 AM
To: 'Loa Andersson' <[e-mail]>; [e-mail]
Cc: [e-mail]; 'DetNet Chairs' <[e-mail]>; [e-mail]
Subject: Re: [mpls] Poll 1: ISD and PSD in the MNA Framework

Hi Loa,

Thanks for this poll.

I agree that:
- The Framework document must be solution independent
- A packet may carry Ancillary Data
- A Network Action is allowed to not require inclusion of Ancillary Data

I also agree that there are two ways to carry Ancillary Data: in-stack and post-stack.

I do not agree that it is a requirement of solution independence that the Framework must specify the support of both in-stack and post-stack. However, I have no objection to allowing both. It was Tianran, I think, who questioned the need for in-stack data, but I agree with him that it seems reasonable for the Framework to describe it unless we can come up with a killer reason why it should not be used. 

I do think that the Framework should flag the concerns (they exist!) with in-stack and post-stack so that a solution is well aware of the choices.
And, given that we plan to support post-stack, we should be clear on the type of cases where in-stack is beneficial (Jim pointed up entropy, but I am not asking to name the use cases, just to help the solution developer do the right thing). Doing that would help Wim's position of wanting to "minimise"
in-stack data.

And, if we allow both, then yes, a packet may carry none, one, or both of the methods. Indeed, an individual Network Action may require none, one, both forms of Ancillary Data.

Cheers,
Adrian
 

-----Original Message-----
From: mpls <[e-mail]> On Behalf Of Loa Andersson
Sent: 30 May 2022 22:21
To: [e-mail]
Cc: [e-mail]; DetNet Chairs <[e-mail]>; [e-mail]
Subject: [mpls] Poll 1: ISD and PSD in the MNA Framework

MPLS working group and and the Open MPLS DT,

The working group chairs believe the current situation is:

The Framework document must be solution independent and say:

a packet may carry Ancillary Data using one or both of the following
methods:

    (1) in-stack, and

    (2) post-stack.

It is up to the document specifying the Network Action to specify which method is to be used for which Ancillary Data.

Note, a Network Action may not require inclusion of Ancillary Data.

Is this the consensus of the working group? Please respond to the MPLS WG mail list.


Loa Andersson
for the Open DT wg chairs

-- 
Loa Andersson                        email: [e-mail]
Senior MPLS Expert                          [e-mail]
Bronze Dragon Consulting             phone: [phone]

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