Subject: [core] stateless --- advice on replay windows

From: Michael Richardson <[email-masked]>
Date: Mon, 26 Oct 2020 13:55:43 -0400

In pull request:
   https://github.com/core-wg/stateless/pull/11/files#diff-cf7b3529858e66fcec2a75824b625d78d48be9aec680e404c6ed6aa3e4bfce0fR909

At line 901:
   https://github.com/core-wg/stateless/pull/11/files#diff-cf7b3529858e66fcec2a75824b625d78d48be9aec680e404c6ed6aa3e4bfce0fR909

I suggest:

        <t>
          This size of the replay window depends upon the number of
          outstanding requests that need to be outstanding.  This can be
          determined from the rate at which new ones are made, and the
          expected duration in which responses are expected.
        </t>

        <t>
          For instance, given a CoAP ACK_TIMEOUT of 2s, and a request rate of
          10 requests/second, any request that is not answered within 2s will
          be considered to have failed.  Thus at most 20 request can be
          outstanding at a time, and any convenient replay window larger than
          20 will work.  As replay windows are often implemented with a
          sliding window and a bit, the use of a 32-bit window would be
          sufficient.
        </t>

I am looking for some review of this text as to sanity.
Is it good advice?  are my assumption reasonable?

--
Michael Richardson <[email-masked]>   . o O ( IPv6 IøT consulting )
           Sandelman Software Works Inc, Ottawa and Worldwide