Re: [quicwg/base-drafts] Equivalence of preferred_address and NEW_CONNECTION_ID (#3560)

ianswett <> Thu, 09 April 2020 15:32 UTC

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Date: Thu, 09 Apr 2020 08:32:46 -0700
From: ianswett <>
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Subject: Re: [quicwg/base-drafts] Equivalence of preferred_address and NEW_CONNECTION_ID (#3560)
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@DavidSchinazi I agree with your intuition, but I think we discussed this in Zurich and ended up concluding the preferred_address CIDs weren't special.  This was in issue #3348 and also came up in #3353 (which I realize hasn't gone out for a consensus call yet, that PR seems stalled?).

In the upload example, the server needs to know that the client is going to send a lot of data, which it might know via SNI, or it might not.  I tend to think the more annoying restriction is that you can't change from a non-0 length CID to a 0-length one and vice versa.  By supplying a 0-length CID later in the connection along with other CIDs, the client could choose whether it wanted to use a 0-length CID at any time.

Thinking out loud, an easier solution may be a TP like 'accept_empty_connection_id' that indicates at anytime, the peer can switch to a 0-length CID if it wants.  It could either think the 5-tuple is stable or its happy re-establishing the path with a non 0-length CID after a NAT rebind.  In this world, the Connection ID is more of a path re-establishment token.

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