Re: [Tsvwg] Input for draft-paxson-tcp-rto-00.txt

[Vern Paxson <[e-mail]>]

> Even if you get those RTT spikes, this does not argue in favor of a magic 
> number, like 1 second, for an RTO-MIN. It might argue in favor of an RTO 
> that keeps a longer history of the past.

Again, the number is magic because it's widespread existing practice and
known to be conservative.  The "RTO that keeps a longer history of the
past" is certainly a possiblity for **future** development of the RTO
algorithm, but that is not the scope of this document.

> The issue of RTT spikes or situations where the RTT suddenly increases and 
> stays at that level is exactly why I believe that the RTO-MIN should be 
> defined as (R' + 2 * G), where R' is the latest RTT measurement, as done in 
> FreeBSD.

Where are you getting this?  FreeBSD doesn't have a R' factor, unless
you're counting the restarting of the timer as new acks come in, which is
already in the description of the algorithm in the I-D.  And G = 500 msec
in the FreeBSD distribution.

		Vern