Return to BSD News archive
Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!munnari.OZ.AU!spool.mu.edu!usenet.eel.ufl.edu!news-res.gsl.net!news.gsl.net!hunter.premier.net!news.mathworks.com!newsfeed.internetmci.com!netnews.nwnet.net!symiserver2.symantec.com!usenet
From: tedm@agora.rdrop.com
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Batch FTP and Web Pages
Date: 27 Jul 1996 18:07:20 GMT
Organization: Symantec Corporation
Lines: 23
Message-ID: <4tdlso$rgb@symiserver2.symantec.com>
References: <31D4AA3A.BC0@www.play-hookey.com> <4rr0us$fj@anorak.coverform.lan> <4rtrbh$2s8@avondale.demon.co.uk> <31E7146D.2FCE@www.play-hookey.com> <4s9n03$179@avondale.demon.co.uk> <837343189snz@dsl.co.uk>
Reply-To: TOMD@cpinc.com
NNTP-Posting-Host: 198.6.34.2
X-Newsreader: IBM NewsReader/2 v1.2
In <837343189snz@dsl.co.uk>, Brian {Hamilton Kelly} <bhk@dsl.co.uk> writes:
[much deleted]
>Besides, one should NEVER place any confidence in the RTTs listed by the
>traceroute program. Since it uses a type of ICMP packet which routers
>are permitted to treat with a low priority, the delays introduced by busy
>routers can manifest an adverse and unrealistic RTT which won't exist for
>real UDP or TCP datagrams.
However,
From what I know it is possible to program routers these days to prioritize
all kinds of traffic based on it's port number, network, host, etc.
So, even though the router can elect to throw away the traceroute packets,
if it is so busy that it is doing that then it probably is throwing away other
packet traffic as well. So, even though the traceroute numbers aren't exact
real TCP and UDP traffic isin't going to necessairly fare any better!
Your other point is valid, though. RTT can only be accurately calculated
by a series of tests averaged over a time period, not by single packet
tests.