Re: latency vs. packet loss

[Alex Bligh <amb () gxn net>]

Jon,

> How well does latency correlate to packet loss on the Internet?  For 
> example, if one were to pick one of several randomly placed sites on 
> the net based on lowest latency to/from point x, what percentage of 
> this time would this also yield the site with the lowest packet loss 
> to/from point x?  My guess is that the correlation is high (due to 
> typical buffer sizes).  

Remember latency is also affected by other things, like distance
(you won't get less than 70ms RTT NY<->Lon even on an empty STM-1),
and to some extent things like line speed and traffic shaping (your
50 byte ping on a 1kb/s (empty) circuit will take 2*50*8/1000 = almost
a second) to transmit. But this is stating the obvious.

Also note there are some conditions which cause packet loss which
won't cause ICMP latency (line errors, various IXP overload conditions
etc.).


-- 
Alex Bligh
GX Networks (formerly Xara Networks)