Network for Sale

Wed Feb 21 20:43:18 UTC 2001

In message <200102212028.MAA50344 at redpaul.mfnx.net>, Paul A Vixie writes:
>
>>> Oh god, I hope not.  RTT has never been an accurate predictor of end-to-end
>>> performance. (Just ask anyone who bought into ping-based global server load
>>> balancing.)  ASPATH length is almost as bad (as a predictor) as RTT.
>> 
>> well, it's the way icmp_echo is handeld in some vendor routers and
>> sometime also the poor implementation of an IP stack on the echoing
>> device which is a problem.
>
>no, that is not the problem.  oh i admit that ping time jitter is ~random.
>but even if it weren't, RTT doesn't drive performance, (bw*delay)-loss does.
>
And how does "delay" differ from RTT, except for the obvious constant 
factor?

		--Steve Bellovin, http://www.research.att.com/~smb