[sfc] Additional AD review comments on draft-ietf-sfc-nsh-20

[Alia Atlas <[e-mail]>]

Carlos,

The draft is much improved.  Thank you for your hard work.  I still see the
following three issues.


1) Sec 2.2: "The O bit MUST be set for OAM packets and MUST NOT be set for
non-OAM
   packets.  The O bit MUST NOT be modified along the SFP."
What happens if the packet is reclassified - potentially to a different
SFP?

Sec 3 doesn't clarify this."When the logical classifier performs re-
       classification that results in a change of service path, it MUST
       replace the existing NSH with a new NSH with the Base Header and
       Service Path Header reflecting the new service path information
       and MUST set the initial SI.  Metadata MAY be preserved in the
       new NSH."

It would be good to specify the behavior for the unassigned flags as well;
that way there will be consistent assumptions for future extensions, if
needed.

2) Sec 7.1: "For example, if the metadata conveys tenant information, that
information may need to be authenticated and/or encrypted between the
originator and the
   intended recipients (which may include intended SFs only)."
A reference to draft-reddy-sfc-nsh-encrypt, which defines how to encrypt
the meta-data would be most helpful in making this sound less aspirational;
so would having that draft not be 2 years expired and ignored by the WG.

3) Sec 11.2.5: Guidance for the expert review is needed.

Regards,
Alia