Re: [quicwg/base-drafts] Skip a packet number when sending one PTO packet (#2952)

Kazuho Oku <notifications@github.com> Tue, 06 August 2019 07:21 UTC

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Subject: Re: [quicwg/base-drafts] Skip a packet number when sending one PTO packet (#2952)
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kazuho commented on this pull request.



> @@ -601,7 +601,9 @@ removed from bytes in flight when the Initial and Handshake keys are discarded.
 When a PTO timer expires, a sender MUST send at least one ack-eliciting packet
 as a probe, unless there is no data available to send.  An endpoint MAY send up
 to two full-sized datagrams containing ack-eliciting packets, to avoid an
-expensive consecutive PTO expiration due to a single lost datagram.
+expensive consecutive PTO expiration due to a single lost datagram.  When only
+sending a single packet on PTO, senders can skip a packet number to elicit a
+faster acknowledgement.
 

@larseggert IIUC, the receiver of a PING is not required to send an ACK immediately.

My slight preference goes to handling the issue below the framing layer, because it'd be only after you've generated the payload of a packet (by gathering frames) that you discover that the packet that is going to be sent is a tail.

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