On 11/25/06, Gerrit Renker <[EMAIL PROTECTED]> wrote:
[CCID 3]: Consolidate timer resets
The specification in [RFC 3448, 4.4, step (3)] is impossible to
implement: when no feedback has been received, the value of RTT
is undefined as per [RFC 3448, 4.2]. Hence we can not set the
timeout value to max(4*R, 2*s/X) as step (3) suggests.
The most reasonable solution is to remain at the initial timeout
value of 2 seconds, as per [RFC 3448, 4.2] - until an estimate
for R has been computed.
But RFC4342 says:
If the sender hasn't
received a feedback packet from the receiver when the nofeedback
timer expires, then the sender halves its allowed sending rate. The
allowed sending rate is never reduced below one packet per 64
seconds. Note that not all acknowledgements are considered feedback
packets, since feedback packets must contain valid Loss Intervals,
Elapsed Time, and Receive Rate options.
If the sender never receives a feedback packet from the receiver, and
as a consequence never gets to set the allowed sending rate to one
packet per RTT, then the sending rate is left at its initial rate of
one packet per second, with the nofeedback timer expiring after two
seconds. The allowed sending rate is halved each time the nofeedback
timer expires. Thus, if no feedback is received from the receiver,
the allowed sending rate is never above one packet per second and is
quickly reduced below one packet per second.
--
Ian McDonald
Web: http://wand.net.nz/~iam4
Blog: http://imcdnzl.blogspot.com
WAND Network Research Group
Department of Computer Science
University of Waikato
New Zealand
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