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

ianswett <notifications@github.com> Thu, 26 March 2020 14:46 UTC

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Subject: Re: [quicwg/base-drafts] PTO probes are sent too frequently (#3546)
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If the server keeps quickly ACKing packets but not sending handshake data, then yes, the client will keep sending full-sized packets, believing the server is blocked by the anti-amplification limit.

At first I thought this couldn't happen in a real-world scenario, but possibly if one had async TLS handshaking so the ServerHello could not be sent immediately upon receipt of the ClientHello and the server and client were very close, a packet could be exchanged as quickly as 1 packet each direction per kGranularity time until the async process returned?

TCP doesn't have an anti-amplification limit and it doesn't require Handshake packets to provide address validation.

I would characterize this as an issue with the client's anti-deadlock response, rather than a problem with PTO.

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