[e2e] [tcpm] RTTM + timestamps

William Allen Simpson william.allen.simpson at gmail.com
Thu Jul 28 13:48:29 PDT 2011


On 7/28/11 8:37 AM, Detlef Bosau wrote:
>  From what I've seen from Richard, Richards concern is to get TCP RTT samples with a much finer resolution than we do today.
>
> Particularly your own work targets at the feasibility for the RTT sampling mechanism from RFC 2988 (IIRC) for WWAN.
>
> While I don't think that we really have an issue with the TCP clock resolution, at least no new one, finding suitable RTOs for WWAN is an important issue for TCP in conjunction with WWAN.
>
A couple of years ago, when I first asked this list about TCPCT related
work, *several* folks wanted finer grained resolution.  So, I added the
64-bit NTP4-format timestamps.  Then, many months later, a naysayer raised
the possibility that NTP5 will someday replace NTP4.  I had to redo the
format to be even more extensible, rendering my extant code obsolete....

But I don't know anybody actually writing the code for 64-bit timestamps
though, let alone NTP5-sized.  Would folks be interested in a draft
describing them?  Would that help move things along?


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