[34882] in North American Network Operators' Group
Re: Network for Sale
daemon@ATHENA.MIT.EDU (Steven M. Bellovin)
Wed Feb 21 15:58:27 2001
From: "Steven M. Bellovin" <smb@research.att.com>
To: Paul A Vixie <vixie@mfnx.net>
Cc: nanog@nanog.org
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Date: Wed, 21 Feb 2001 15:43:18 -0500
Message-Id: <20010221204318.9EE9435C42@berkshire.research.att.com>
Errors-To: owner-nanog-outgoing@merit.edu
In message <200102212028.MAA50344@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
