Re: [quicwg/base-drafts] PTO MUST send new data or retransmit data if possible (#3057)

Benjamin Saunders <notifications@github.com> Mon, 23 September 2019 23:34 UTC

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Subject: Re: [quicwg/base-drafts] PTO MUST send new data or retransmit data if possible (#3057)
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Ralith commented on this pull request.



>  
-When there is no data to send, the sender SHOULD send a PING or other
-ack-eliciting frame in a single packet, re-arming the PTO timer.
+It is possible the sender has no new or previously-sent data to send.
+As an example, consider the following sequence of events: new application data
+is sent in a STREAM frame, deemed lost, then retransmitted in a new packet,
+and then the original transmission is acknowledged.  When there is no data to
+send, the sender SHOULD send a PING or other ack-eliciting frame in a single
+packet, re-arming the PTO timer.

In this case, the second packet is ack-eliciting and has not been acknowledged, eventually leading to a probe timeout. However, there is no unsent or sent-but-unacknowledged ack-eliciting data available to send, so a `PING` is fabricated instead.

Perhaps "there is new or previously sent data" should be more specific?

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