Re: [quicwg/base-drafts] Description of the use of Preferred Address is unclear (#3353)

Martin Thomson <notifications@github.com> Mon, 20 January 2020 10:03 UTC

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Subject: Re: [quicwg/base-drafts] Description of the use of Preferred Address is unclear (#3353)
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As requested, I'm forwarding [this comment](https://github.com/quicwg/base-drafts/pull/3354#discussion_r368419414) regarding:

> Retirement of either of these connection IDs notifies the server of the address the client has chosen.

This implies a semantic to the retirement of connection IDs that is not already defined. It says that in addition to releasing the resource, the server can say definitively that those other network paths won't be used. But this is misleading because retiring CID 1 does not prevent CID 4 from being used on that path. Nothing says that the connection IDs sent in NEW_CONNECTION_ID have to be used on one or other path. Better to keep the requirement where it is: don't migrate back if you use a preferred address.

Yes, that means that servers can't be sure of behaviour of clients here, but they can use the destination address to confirm acceptance of the preferred address or not. That should suffice.

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