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To: "'ILUG'" <ilug@linux.ie>
Subject: Re: [ILUG] Modem question
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X-Mas: Bah humbug.
From: Rick Moen <rick@linuxmafia.com>
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X-Original-Date: Tue, 8 Oct 2002 12:06:33 -0700
Date: Tue, 8 Oct 2002 12:06:33 -0700

Quoting Breathnach, Proinnsias (Dublin) (breatpro@exchange.ie.ml.com):

> Is there any reliable way to calculate your connection speed if you don't
> trust what the modem reports?

Do a wget of a file of known length, in a script that runs "date" before
and after (or equivalent).

Be aware that speed between you and your upstream link is one thing;
speed through countless congested routers to a faraway location may be
quite another.  Remember that hardware-level compression is a factor.
(The file you wget will probably be precompressed.)

In the area of the slightly more exotic, be aware that different traffic
may have higher priority and thus more available bandwidth at various
points in the transit to/from you -- and that some traffic may go via 
different paths coming vs. going.

Be aware that raw bulk transfer speed may not be the only thing that
matters:  Depending on what you're doing, the modem's connection latency
might matter, and this differs widely between modems.  (It matters more
for interactive sessions, e.g., ssh remote logins, where each keystroke
is echoed from remote.)

-- 
Cheers,                    "Send a policeman, and have it arrested."
Rick Moen                     -- Otto von Bismarck, when asked what he 
rick@linuxmafia.com               would do if the British Army landed.
-- 
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