[Gllug] Calculating 'real' bandwidth

[Pete Ryland]

On 15/03/07, Russell Howe <rhowe at siksai.co.uk> wrote:
> Well, we know how big an ACK is, and we know how many packets per second
> need ACKing (585), so it's easy - 106 * 585 = 62010 bytes/s of ACKs,
> which is 496,080 bits/s
>
> Yep, that's right, 500Kbit/s of upstream is taken just ACKing your
> downstream TCP traffic if you're going at full pelt!
>
> If you were running optimally, it's slightly worse - at 610 TCP packets
> per second, that's 64,660 bytes/s or 517,280 bits/s of upstream
> bandwidth taken up by TCP ACKs

It's been over 10 years since I last looked closely at this, but as
far as I can recall, I thought the way sliding window worked allowed
you to ACK more than one packet at the same time, that is, an ACK-n
says "I've seen everything up to n."

Pete
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