Re: [mpls] FW: New Version Notification for draft-jags-mpls-ps-mna-hdr-00.txt

Loa Andersson <[email protected]> Thu, 16 Mar 2023 19:56:13 +0100
Newsgroups gmane.ietf.pwe3,gmane.ietf.mpls
Message-ID <[email protected]>
Rakesh,

Thanks for response, I'd like to point out

- the first nibble is never on its own a sufficient indication for what
   the payload a a packet is, it might be an Ethernet PW without control
   word, where the first nibble accidentally is a value that we assigned
   for some payload.
- something more is needed to with sufficient accuracy understand what
   the payload is, for PSD this is the P-bit in the OpCode LSE.
- actually the the P-bit in the OpCode LSE is sufficient in itself, we
   don't need the first nibble, unless we for some reason want both
   brace and waist belt, but I can't see why
- first nibbles is a scarce resource that should only be allocated if we
   really need it.

Maybe someone from the the pseudo wire side of the house can confirm this.

/Loa


On 2023-03-15 13:16, Rakesh Gandhi wrote:
> Hi Loa,
> 
> Authors discussed the first nibble after BOS.
> Re-using any existing Nibble (e.g. 0000b for CW or 0001b for G-ACH) can 
> lead to backwards compatibility issues on the legacy devices.
> Note that legacy devices may not support MNA sub-stack.
> It would be good to assign a new nibble (e.g., 0x2 = 0010b, currently 
> not assigned) to avoid such issues.
> We can agree on this (i.e. assigning a new nibble for PSD), we can 
> update the draft accordingly.
> 
> thanks,
> Rakesh
> 
> 
> 
> 
> On Fri, Mar 10, 2023 at 9:40 AM Loa Andersson <[email protected] 
> <mailto:[email protected]>> wrote:
> 
>     All,
> 
>     I have a question that is not new, and I’m still uncertain what the
>     correct answer is.
> 
>     I’m not certain that we should consider “the first nibble” as part
>     of the MNA PSD. Admittedly it is part of PSD, but not part of the
>     MNA PSD.
> 
>     We could say that MNA PSD start after the first nibble. If the
>     PSD-bit is set in the MNA-label LSE, we can safely ignore the first
>     nibble, if it is not set we need to look at the first nibble, and
>     the data following the first nibble is not MNA ancillary data.
> 
>     I see no meed to define a PSD first nibble. It would also avoid a
>     potential ambiguity in using the Generic Associated Channel nibble.
> 
>     For MNA the first should be set to 0000b when sent, and ignored when
>     received.
> 
>     /Loa
> 
>     Sent from my iPhone
> 
>>     On 10 Mar 2023, at 13:59, Jaganbabu Rajamanickam (jrajaman)
>>     <[email protected]
>>     <mailto:[email protected]>> wrote:
>>
>>     
>>
>>     Hello Everyone,____
>>
>>     __ __
>>
>>        We like to introduce our new draft on Post-Stack MNA solution.____
>>
>>        Welcome your review comments and suggestions.____
>>
>>     __ __
>>
>>     Thanx,____
>>
>>     Jags____
>>
>>     __ __
>>
>>     *From: *[email protected] <mailto:[email protected]>
>>     <[email protected] <mailto:[email protected]>>
>>     *Date: *Friday, March 10, 2023 at 7:52 AM
>>     *To: *Jaganbabu Rajamanickam (jrajaman) <[email protected]
>>     <mailto:[email protected]>>, Jie Dong <[email protected]
>>     <mailto:[email protected]>>, Rakesh Gandhi (rgandhi)
>>     <[email protected] <mailto:[email protected]>>, Royi Zigler
>>     <[email protected] <mailto:[email protected]>>, Tony
>>     Li <[email protected] <mailto:[email protected]>>
>>     *Subject: *New Version Notification for
>>     draft-jags-mpls-ps-mna-hdr-00.txt____
>>
>>
>>     A new version of I-D, draft-jags-mpls-ps-mna-hdr-00.txt
>>     has been successfully submitted by Jaganbabu Rajamanickam and
>>     posted to the
>>     IETF repository.
>>
>>     Name:           draft-jags-mpls-ps-mna-hdr
>>     Revision:       00
>>     Title:          Post-Stack MPLS Network Action (MNA) Solution
>>     Document date:  2023-03-10
>>     Group:          Individual Submission
>>     Pages:          17
>>     URL:
>>     https://www.ietf.org/archive/id/draft-jags-mpls-ps-mna-hdr-00.txt
>>     <https://www.ietf.org/archive/id/draft-jags-mpls-ps-mna-hdr-00.txt>
>>     Status:
>>     https://datatracker.ietf.org/doc/draft-jags-mpls-ps-mna-hdr/
>>     <https://datatracker.ietf.org/doc/draft-jags-mpls-ps-mna-hdr/>
>>     Html:
>>     https://www.ietf.org/archive/id/draft-jags-mpls-ps-mna-hdr-00.html
>>     <https://www.ietf.org/archive/id/draft-jags-mpls-ps-mna-hdr-00.html>
>>     Htmlized:
>>     https://datatracker.ietf.org/doc/html/draft-jags-mpls-ps-mna-hdr
>>     <https://datatracker.ietf.org/doc/html/draft-jags-mpls-ps-mna-hdr>
>>
>>
>>     Abstract:
>>        This document defines the Post-Stack MPLS Network Action (MNA)
>>        solution for carrying Network Actions and Ancillary Data after the
>>        MPLS label stack based on In-Stack MNA solution defined in draft-
>>        ietf-mpls-mna-hdr.  MPLS Network Actions can be used to influence
>>        packet forwarding decisions, carry additional OAM information
>>     in the
>>        MPLS packet or perform user-defined operations.  This document
>>        addresses the MNA requirements specified in draft-ietf-mpls-mna-
>>        requirements.  This document follows the MNA framework specified in
>>        draft-ietf-mpls-mna-fwk.
>>
>>
>>
>>
>>     The IETF Secretariat
>>
>>     ____
>>
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-- 
Loa Andersson                        email: [email protected]
Senior MPLS Expert                          [email protected]
Bronze Dragon Consulting             phone: +46 739 81 21 64

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