Re: [sfc] Robert Wilton's Discuss on draft-ietf-sfc-ioam-nsh-11: (with DISCUSS and COMMENT)

["Frank Brockners (fbrockne)" <[e-mail]>]

Hi Rob,

Please see inline...

> -----Original Message-----
> From: Rob Wilton (rwilton) <[e-mail]>
> Sent: Friday, 5 May 2023 11:36
> To: Frank Brockners (fbrockne) <[e-mail]>; The IESG
> <[e-mail]>
> Cc: [e-mail]; [e-mail]; [e-mail];
> [e-mail]
> Subject: RE: Robert Wilton's Discuss on draft-ietf-sfc-ioam-nsh-11: (with
> DISCUSS and COMMENT)
> 
> Hi Frank,
> 
> Please see comments inline.
> 
> > -----Original Message-----
> > From: Frank Brockners (fbrockne) <[e-mail]>
> > Sent: 04 May 2023 21:21
> > To: Rob Wilton (rwilton) <[e-mail]>; The IESG <[e-mail]>
> > Cc: [e-mail]; [e-mail];
> > [e-mail]; [e-mail]
> > Subject: RE: Robert Wilton's Discuss on draft-ietf-sfc-ioam-nsh-11:
> > (with DISCUSS and COMMENT)
> >
> > Hi Rob,
> >
> > Thanks a lot for your review. We've just posted an updated revision (12):
> > https://www.ietf.org/archive/id/draft-ietf-sfc-ioam-nsh-12.txt
> >
> > Please see inline below:
> >
> > > -----Original Message-----
> > > From: Robert Wilton via Datatracker <[e-mail]>
> > > Sent: Tuesday, 2 May 2023 14:53
> > > To: The IESG <[e-mail]>
> > > Cc: [e-mail]; [e-mail];
> > > [e-mail]; [e-mail];
> > > [e-mail]
> > > Subject: Robert Wilton's Discuss on draft-ietf-sfc-ioam-nsh-11:
> > > (with DISCUSS and COMMENT)
> > >
> > > Robert Wilton has entered the following ballot position for
> > > draft-ietf-sfc-ioam-nsh-11: Discuss
> > >
> > > 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-sfc-ioam-nsh/
> > >
> > >
> > >
> > > --------------------------------------------------------------------
> > > --
> > > DISCUSS:
> > > --------------------------------------------------------------------
> > > --
> > >
> > > Hi,
> > >
> > > Thanks for this document.
> > >
> > > A couple of discuss points that I raised only because I find the
> > > spec to be unclear which should be be easy to clarify:
> > >
> > > (1) p 2, sec 3.  IOAM encapsulation with NSH
> > >
> > >                                                        The operator MUST
> > >    ensure that all nodes along the service path support IOAM.
> > >
> > > Is it actually 'all nodes along the service path' or "SFC aware
> > > nodes along the service path" that MUST support IOAM?
> >
> > ...FB: Thanks. The sentence has been updated to read:
> >
> > The operator MUST ensure that SFC-aware
> >    nodes along the Service Function Path support IOAM, otherwise packets
> >    might be dropped (see Section 3 further below, as well as [RFC8300]
> >    Section 2.2).
> [Rob Wilton (rwilton)]
> Looks good.  Thanks.
> 
> >
> > >
> > > (2) p 3, sec 3.  IOAM encapsulation with NSH
> > >
> > >       IOAM HDR Len:  8 bit Length field contains the length of the IOAM
> > >          header in 4-octet units.
> > >
> > > Does this mean quantized to 4 byte units, or that the actual length
> > > in bytes is
> > > 4 * "Hdr Len" field?
> >
> > ...FB: John had a related comment on the length field. The updated
> > version now reads:
> >
> >       IOAM HDR Len:  8-bit field that contains the length of the IOAM
> >          header in multiples of 4-octets, including the "IOAM-Type" and
> >          "IOAM HDR Len" fields.
> [Rob Wilton (rwilton)]
> 
> So, just to check that I definitely understand.  If the hdr len field = 3, then
> that means that the actual length is 12 octets (3 x 4)?  If so, that is fine for
> me to clear the discuss.  If not, then the text isn't clear, at least to me :-)

...FB: Yes. (IOAM HDR Len) * 4 octets = total number of octets. If " IOAM HDR Len" = 3, then total number of octets is 12.
The text uses the same wording as e.g. RFC 9197 now. 

Cheers, Frank

> 
> Regards,
> Rob