Hi!
Quite a technical question: what does affect ping time? I have replied to myself in this way:
a) net congestion
b) inter-AS routing
c) the two peer's TCP/IP congestion (and middle routers, too)
d) the speed of the line you're on (???)

If it's true that point d) does affect ping time, why is it a measure to see if a host is reliable? If I am on a dial-up connection I will get different measures than if I were on a DSL line!

And when I ping a host, it is correct to stop the other net traffic on my computer? Or this shouldn't change measures? (it actually does)

And finally, can you post average stats of typical ping times on different lines? e.g., with a 56k modem what should I expect from a reliable host? And with a ADSL line? ect.

Anybody? :confused:

I'm writing a research paper on this right now so I might as well answer: The minimum round trip time (out of a series of pings) is an accurate measure of the "speed of light" for that packet, consisting of 1. Transmission delay (signals travel at about 2/3 c along both copper and fiber optics), 2. Protocol stack delays (usually insignificant and approximately fixed), and 3. Transmission time (packet size divided by bandwidth, summed over all hops). On the other hand, the standard deviation round trip time is an accurate measure of congestion, since it comes from variability in router queue lengths.

To a first approximation, any individual ping will only really tell you how far away the destination is; if you want to know how congested a network (including your own connection) is then you must look at the standard deviation (variability) of the ping times.