Re: [Bloat] Goodput fraction w/ AQM vs bufferbloat

[Fred Baker <fred@cisco.com>]

On May 6, 2011, at 8:14 AM, richard wrote:
> If every packet takes two attempts then the ratio will be 1/2 - 1 unit
> of googput for two units of throughput (at least up to the choke-point).
> This is worst-case, so the ratio is likely to be something better than
> that 3/4, 5/6, 99/100 ??? 

I have a suggestion. turn on tcpdump on your laptop. Download a web page with lots of imagines, such as a google images web page, and then download a humongous file. Scan through the output file for SACK messages; that will give you the places where the receiver (you) saw losses and tried to recover from them.

> Putting a number to this will also help those of us trying to get ISPs
> to understand that their Usage Based Bilking (UBB) won't address the
> real problem which is hidden in this ratio. The fact is, the choke point
> for much of this is the home router/firewall - and so that 1/2 ratio
> tells me the consumer is getting hosed for a technical problem.

I think you need to do some research there. A TCP session with 1% loss (your ratio being 1/100) has difficulty maintaining throughput; usual TCP loss rates are on the order of tenths to hundredths of a percent.