Thanks everyone for all the good advice. I will summarize my responses to all your notes now, then I'll go away and run more tests.
- Yes, I am using netperf 2.6.0 and netperf-wrapper from Toke's github repo.
- The "sync rate" is the speed with which the DSL modem sends bits to/from my house. I got this by going into the modem's admin interface and poking around. (It turns out that I have a very clean line, high SNR, low attenuation. I'm much less than a km from the central office.) So actual speed should approach this, except...
- Of course, I have to subtract all those overheads that Sebastian described - ATM 48-in-53, which knocks off 10%; ATM frame overhead which could add up to 47 bytes padding to any packet, etc.)
- I was astonished by the calculation of the bandwidth consumed by acks in the reverse direction. In a 7mbps/768kbps setting, I'm going to lose one quarter of the reverse bandwidth? Wow!
- I wasn't entirely clear how to set the target in the SQM GUI. I believe that "target ##msec" is an acceptable format. Is that correct?
- There's also a discussion of setting the target with "auto", but I'm not sure I understand the syntax.
Now to find some time to go back into the measurement lab! I'll report again when I have more data. Thanks again.
Rich
Do you have the latest (head) version of netperf and netperf-wrapper? some changes were made to both that give better UDP results.
-Aaron