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

Tatsuhiro Tsujikawa <> Tue, 24 September 2019 01:15 UTC

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From: Tatsuhiro Tsujikawa <>
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Subject: Re: [quicwg/base-drafts] PTO MUST send new data or retransmit data if possible (#3057)
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tatsuhiro-t 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.

I think this kind of situation only happens when client sent Initial and received its ACK but either sever Initial or Handshake was lost.  Client then literally has nothing to send.  And forced to send ack-eliciting frame (and controversially, draft-23 does not allow PING here).

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