Re: [Bloat] Random idea in reaction to all the discussion of TCPflavours - timestamps?

[david@lang.hm]

On Sun, 20 Mar 2011, Jonathan Morton wrote:

> I think we can come up with some simple empirical rules for choosing queue sizes.  I may be half-remembering something VJ wrote, but here's a starting point:
>
> 0) Buffering more than 1 second of data is always unacceptable.

what about satellite links? my understanding is that the four round trips 
to geosync orbit  (request up, down, reply up down) result in approximatly 
1 sec round trip.

David Lang

> 1) Measure (or estimate) the RTT of a full-sized packet over the exit link and back, then add 100ms for typical Internet latency, calling this total T1.  If T1 is more than 500ms, clamp it to 500ms.  Calculate T2 to be twice T1; this will be at most 1000ms.
>
> 2) Measure (or estimate) the throughput BW of the exit link, in bytes per second.
>
> 3) Calculate ideal queue length (in bytes) Q1 as T1 * BW, and the maximal queue length Q2 as T2 * BW.  These may optionally be rounded to the nearest multiple of a whole packet size, if that is convenient for the hardware.
>
> 4) If the link quality is strongly time-varying, eg. mobile wireless, recalculate Q1 and Q2 as above regularly.
>
> 5) If the link speed depends on the type of equipment at the other end, the quality of cabling, or other similar factors, use the actual negotiated link speed when calculating BW.  When these factors change, recalculate as above.
>
> I would take the "hysteresis limit" to be an empty queue for the above algorithm.
>
> - Jonathan
>
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