[core] Spencer Dawkins' No Objection on draft-ietf-core-block-19: (with COMMENT)

["Spencer Dawkins" <[e-mail]>]

Spencer Dawkins has entered the following ballot position for
draft-ietf-core-block-19: No Objection

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/iesg/statement/discuss-criteria.html
for more information about IESG DISCUSS and COMMENT positions.


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



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

Please consider whether you need to say more about UDP usage for this
extension than what the base CORE specification says - RFC 7252 has only
one mention of RFC 5405, and that only points to guidance about reducing
ACK_TIMEOUT below one second. I understand that the CoAP story includes
"most of these nodes aren't capable of generating a lot of packets in a
short timeframe", but does this extension make it easier to send multiple
UDP packets back-to-back?

I'm reading this text, 

   In most cases, all blocks being transferred for a body (except for
   the last one) will be of the same size.  

and then this text

      *  The block size implied by SZX MUST match the size of the
         payload in bytes, if the M bit is set.  (SZX does not govern
         the payload size if M is unset).  For Block2, if the request
         suggested a larger value of SZX, the next request MUST move SZX
         down to the size given in the response.  (The effect is that,
         if the server uses the smaller of (1) its preferred block size
         and (2) the block size requested, all blocks for a body use the
         same block size.)
         
and realizing that I'm confused about why all the blocks for a body might
NOT use the same block size. Maybe this doesn't matter (because an
implementation would need to be prepared for the case when all the blocks
don't use the same block size)?

The examples were helpful to me. Thank you for doing that work.