North American Network Operators Group

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Re: latency vs. packet loss

  • From: Alex Bligh
  • Date: Thu Jan 14 06:41:25 1999


> 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

Alex Bligh
GX Networks (formerly Xara Networks)