Re: [quicwg/base-drafts] PTO probes are sent too frequently (#3546)

ianswett <> Fri, 27 March 2020 10:56 UTC

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Date: Fri, 27 Mar 2020 03:56:28 -0700
From: ianswett <>
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Subject: Re: [quicwg/base-drafts] PTO probes are sent too frequently (#3546)
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I think the most intellectually clean thing to do here would be to not reset PTO count when an ACK is received and the PTO is only armed for anti-amplification purposes.  This is because even though at a transport level, everything is working(ACKs are quickly received), the client is arming the PTO for a very different reason(anti-deadlock).  And the PTO packets aren't allowing the server to make any more progress, because it's not blocked.

But I don't think that suggestion is very easy to implement, so I'm not sure it's what we want.

I'd suggest restricting the client to one anti-deadlock packet per second or some arbitrary period, which would be easier, but means someone has to pick a magic number.  I mention 1 second because it's a magic number already in QUIC recovery(default handshake timeout) and in TCP.  This basically amounts to anti-anti-amplification attack prevention I think :(

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