[mpls] Gunter Van de Velde's No Record on draft-ietf-mpls-msd-yang-12: (with COMMENT)

[Gunter Van de Velde via Datatracker <[e-mail]>]

Gunter Van de Velde has entered the following ballot position for
draft-ietf-mpls-msd-yang-12: No Record

When responding, please keep the subject line intact and reply to all
email addresses included in the To and CC lines. (Feel free to cut this
introductory paragraph, however.)


Please refer to https://www.ietf.org/about/groups/iesg/statements/handling-ballot-positions/ 
for more information about how to handle DISCUSS and COMMENT positions.


The document, along with other ballot positions, can be found here:
https://datatracker.ietf.org/doc/draft-ietf-mpls-msd-yang/



----------------------------------------------------------------------
COMMENT:
----------------------------------------------------------------------

I reviewed version draft-ietf-mpls-msd-yang-12

The draft is clear and in general i see no big issues with the yang model
proposed.

Currently, my ballot is explicitly set to a 'No Record' position as I am
unclear on the history behind why the MSD (Maximum SID Depth) leaves only
provide read-only operational information. I'll update once i understand the
philosophy of MSD model intent better.

Allow me to explain my concern. One might assume that a hardware device
supports, for instance, the most optimal setup where Ethernet encapsulation can
impose 10 MPLS segment SIDs. However, if such an interface is configured with a
more complex L2 encapsulation (such as 802.1q combined with EVPN service SIDs
and Entropy SIDs), the value that controllers can use might be reduced to 8, or
even less, depending on the encoding and encapsulation complexity. In such
scenarios, an operator may wish to adjust the most optimal MSD values to
something less optimal but supported by the hardware when attempting to program
a segment routing policy on a data packet