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Last Call Review of draft-ietf-dprive-padding-policy-04

Request Review of draft-ietf-dprive-padding-policy
Requested revision No specific revision (document currently at 06)
Type Last Call Review
Team Transport Area Review Team (tsvart)
Deadline 2018-04-04
Requested 2018-04-04
Requested by Magnus Westerlund
Authors Alexander Mayrhofer
I-D last updated 2018-04-04
Completed reviews Secdir Last Call review of -04 by Charlie Kaufman (diff)
Genart Last Call review of -04 by Meral Shirazipour (diff)
Opsdir Last Call review of -04 by Joe Clarke (diff)
Tsvart Last Call review of -04 by Magnus Westerlund (diff)
Tsvart Telechat review of -05 by Magnus Westerlund (diff)
Assignment Reviewer Magnus Westerlund
State Completed
Request Last Call review on draft-ietf-dprive-padding-policy by Transport Area Review Team Assigned
Reviewed revision 04 (document currently at 06)
Result Ready w/issues
Completed 2018-04-04
I have reviewed this document as part of TSV-ART task to review documents with
potential transport related issues.

I note that the document in its final recommendation regarding block sizes do
consider MTU for reasonable size choices. What I am missing in Section 4 is the
discussion of MTU as impacting this. From my perspective, it appears reasonable
to: In Section 4.1 consider if the Block Size will interact with the MTU.
Especially for block sizes that are a small fraction of the MTU, unless the
block is chosen so that a multiple just fits the MTU, the block padding may
cause unnecessary fragmentation for UDP based delivery. Also chosing a block
size larger than the MTU of course forces one to always fragment.

In Section 4.2 I think depending on the negotiated size, the downside is that
it will commonly result in a consistent number of fragments reducing delivery
probability. I haven't digged into the negotiation part about maximum response
size. But, I assume that this is not necessarily chose based on MTU
constraints, but other limitations in the system.

Note that these comments only applies for datagram based transport without its
own fragmentation mechanism, e.g. UDP.