I am forwarding this email that I sent earlier - I was using a new
email address that wasn't subscribed to the mailing list.
Begin forwarded message:
Why not just calculate a packet rate per second? Or am I missing
something obvious?
No, that is a good question.
One reason for including the packet size s is discussed in
Section 5.3 of RFC 4342:
"The packet size s is used in the TCP throughput equation. A CCID 3
implementation MAY calculate s as the segment size averaged over
multiple round trip times -- for example, over the most recent four
loss intervals, for loss intervals as defined in Section 6.1.
Alternately, a CCID 3 implementation MAY use the Maximum Packet Size
to derive s. In this case, s is set to the Maximum Segment Size
(MSS), the maximum size in bytes for the data segment, not including
the default DCCP and IP packet headers. Each packet transmitted
then
counts as one MSS, regardless of the actual segment size, and the
TCP
throughput equation can be interpreted as specifying the sending
rate
in packets per second."
Thus, an implementation MAY calculate the allowed sending rate
in bytes per second, using for s the average segment size.
Or an implementation may use the MSS for s, and in fact calculate
the allowed sending rate simply in packets per second. This would be
a purely local implementation decision.
- Sally
http://www.icir.org/floyd/
- Sally
http://www.icir.org/floyd/
