Re: [quicwg/base-drafts] active_connection_id_limit interacts poorly with Retire Prior To (#3193)

Mike Bishop <notifications@github.com> Wed, 06 November 2019 19:36 UTC

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Date: Wed, 06 Nov 2019 11:36:22 -0800
From: Mike Bishop <notifications@github.com>
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Subject: Re: [quicwg/base-drafts] active_connection_id_limit interacts poorly with Retire Prior To (#3193)
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I think a MUST NOT is reasonable; there was considerable pushback in Tokyo for reasons I don't remember clearly.  I don't think you can get out of sync provided the TP is at least 2.

The other possibility, as an implementation, is to track which IDs you've retired/forgotten.  Obviously, the point of not keeping all the CIDs is to reduce the memory consumption and this still requires keeping some memory.  But it's worth pointing out that you don't actually need to have the CID in hand in order to promise you'll never use it again.

For that matter, a naive implementation that wants to save memory at the cost of bytes _could_ retire every CID sequence number up to RPT upon receipt of an increase RPT value, whether it has previously retired it or not.

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