Working Group Last Call (WGLC) comments for draft-ietf-quic-ack-frequency.

[Gorry Fairhurst <[e-mail]>]

Thanks for completing this work. I’ve just read the latest version of 
draft-ietf-quic-ack-frequency as a part of the WGLC, and also checked 
the issues and the diff. Overall, this draft seems a consistent and 
complete document that I think will be useful to publish as a RFC.

I have one request:

In reviewing the issues I see the editors decided to not add any 
recommendation for how often an ACK needs to be sent. I still think this 
is a serious omission that the WG ought to address. In section 8.1, para 
2, the text says  a “sender **CAN** cause a receiver to send ACKs  at 
least once per RTT”….(see #168).  The editors argued (in #211) that this 
document can be impartial on whether this is important, but I think we 
do need to review that: People reviewing specifications in the IETF are 
often reminded that a protocol ought to provide at least one feedback 
packet per RTT to close the control loop when intended for Internet 
deployment, yet this document seeks to relax the ACK procedure for QUIC 
(which I fully agree with), but does not provide this guidance, which I 
would have thought was essential to be published as a PS.

My request is to RECOMMEND at least 1 ACK/RTT when sending data, to 
provide prompt feedback and refer to RFC 8961.

RFC 8961 is BCP and says, for instance:
Timer “observations SHOULD be taken and incorporated into the RTO at 
least once per RTT or as frequently as data is  exchanged in cases where 
that happens less frequently than once per RTT.”

Can we please provide this guidance and add a reference to this guidance?

Best wishes,

Gorry