Re: [quicwg/base-drafts] Remember UDP size limit for 0-RTT (#3498)

Kazuho Oku <notifications@github.com> Wed, 04 March 2020 03:56 UTC

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Subject: Re: [quicwg/base-drafts] Remember UDP size limit for 0-RTT (#3498)
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kazuho commented on this pull request.



>  
 * initial_max_data
 * initial_max_stream_data_bidi_local
 * initial_max_stream_data_bidi_remote
 * initial_max_stream_data_uni
 * initial_max_streams_bidi
 * initial_max_streams_uni
+* max_udp_payload_size

While I agree that it is a good idea to encourage clients to remember the value, I'm not sure if we want to add max_udp_payload_size to this list. That is because doing so mandates the server to remember the max_udp_payload_size value that it advertised in the previous connection, and to not accept 0-RTT if the value has changed.

When a client reconnects from a different path, a path that the server thinks it is better to have smaller MTUs, it might be a good idea to let the server reduce the MTU. If 0-RTT packets succeed to come through (due to it being small or due to the maximum MTU being larger than what the server thinks is safe), there is no reason to drop them, just because max_udp_payload_size is going to be different.

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