One thing about the famous "500 miles" post that I realized doesn't make sense:
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An odd feature of our campus network at the time was that it was 100%
switched. An outgoing packet wouldn't incur a router delay until hitting
the POP and reaching a router on the far side. So time to connect to a
lightly-loaded remote host on a nearby network would actually largely be
governed by the speed of light distance to the destination rather than by
incidental router delays.
Feeling slightly giddy, I typed into my shell:
$ units
1311 units, 63 prefixes
You have: 3 millilightseconds
You want: miles
* 558.84719
/ 0.0017893979
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But surely for Sendmail to register a "connect" with a remote SMTP server would require at least one (or many?) round trips to the remote server, so one-way speed of light time doesn't seem like it would really be relevant. Am I missing something?
Possibly the introduction wherein the author says:
"The story is slightly altered in order to protect the guilty, elide over irrelevant and boring details, and generally make the whole thing more entertaining."
If memory serves he goes into further detail about the alterations and some common objections to the story in his FAQ:
I believe one version of this story explains that the math (and the situation) has been simplified for the sake of this story in order to make it readable.
Makes sense, I can share this story to people without any computer knowledge, but something explaining how connections are established would be wholly incomprehensible to them.
What in the world could possibly be the reason in that first story for the 'file' program to look for the string 'Tue' and change to the Jam filetype? That's gotta be a very niche case, right?
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An odd feature of our campus network at the time was that it was 100% switched. An outgoing packet wouldn't incur a router delay until hitting the POP and reaching a router on the far side. So time to connect to a lightly-loaded remote host on a nearby network would actually largely be governed by the speed of light distance to the destination rather than by incidental router delays.
Feeling slightly giddy, I typed into my shell:
$ units 1311 units, 63 prefixes
You have: 3 millilightseconds You want: miles * 558.84719 / 0.0017893979
----
But surely for Sendmail to register a "connect" with a remote SMTP server would require at least one (or many?) round trips to the remote server, so one-way speed of light time doesn't seem like it would really be relevant. Am I missing something?