I have been having performance problems with my DSL link for some time. Since I work at home, I am pretty quick to notice problems. The issue has to do with the RTTs across the DSL link itself. That is, when I ping the router at the Intrex end of my link from my home LAN, RTTs jump to 200-500ms for minutes at a time. This is when the link is idle (I am neither uploading or downloading data, and the modem light on my TP-LINK shows the DSL modem as being idle. I am quite certain of this.)
My methodology is simple: I send out 30 "pings", each separated by 10 seconds, and then average the results together to produce one sample over the 5 minute interval. Thus, a value of 200ms indicates the RTT was not just an instantaneous sample (which one would expect), but reflects a sustained load over a 5 minute interval.
When there are no issues, I regularly see RTTs in the 30-50ms range. But when the RTTs are above 200ms, the link is essentially unusable (i.e., web pages take forever to load, and interactive telnet/ssh sessions are unbearable). Configuration information:
I've been having problems for months. I finally called Intrex on June 18, and was told that I had an old modem (on a FR link) and that I would first have to upgrade to an ATM modem, which I did. This did not fix the problem, but I went on travel shortly thereafter and did not followup up.