Bud Krueger wrote:>... There must be some reason why we should use the mirror
site, but
>for the life of me I can't think of what it is.
There is a rumour that the 'net is free, but believe me the cables
and satallites that carry the information are not. In my case the
actual costs are more transparent then they are with a typical
service provider.
When you want to get on the net, you find a convenient internet
service provider who is 'on' the net, and you contract for a cable
to run between your facility and theirs. The cable that you contract
is a dial-up telephone line for most of us, but it could be a cable
-tv cable, or a dedicated special cable. If you run a business and
want to have your web-site computers physically there next to you,
you would probably contract with the telephone company for what is
essentially a dedicated cable directly from you to the ISP.
Your service provider is in turn linked to one or more other 'nodes'
on the internet, in each case on some kind of cable that someone on
one end or the other is paying for. This is the 'net' Each time YOUR
information gets to a 'node' that is not its destination it is
cleverly forwarded to a note that gets it closer to you; and so on
etc.
I am at a UK University. When everything internet started hapenning
over here the UK universities had a pre-existing network called
JANET (Joint Academic Network). We had our network, the US had
ARPANET or whatever, and a contract was made for a very long wire
to run between them. Voila! Now we can read 'usenet news' and write
emails to our friends in Berkeley.
Then came HTML, Netscape, and Internet Explorer. Now instead of a
22k text message we have a 22k text message, about a dozen buttons
each with a graphics file of 22k, and a 220k backgound image and
possiby even a bunch of photographs. We complain to the geeks at
JANET that we often can't connect to web pages, FTP sites or
whatevers in the US, and that when we DO connect it is really
slow. So the Geeks take a look at the problem and say, "Gosh, we
have as much information travelling on our cable as it can carry,
and the rest just waits until the originating computer says
'enough! I give up!'. We didn't buy a big enough cable" So the
JANET board gets together and ponders what to do about the
problem. A bigger cable is expensive, and no other UK ISP is just
going to route all of our excess traffic to the US without
getting paid for it, because they have to pay for their cables as
well.
One of the board members asks "what is everyone reading that
causes so much transatlantic traffic?". The response is "the
most looked at pages are the default startup pages for Explorer
and Netscape, they get checked about 5 gazillion times a day.
Next in line is various archives and information repositories.
They decide to create mirrors of the latter, and do caching of
the former. Then the computer gurus at each university are to
be very strict in instructing people to set up their browsers
to use a proxy cache (to that really popular pages only cross
the atlantic once every hour or so instead of thousands of times)
and to tell people to use the UK or European Mirror sites when
such are available.
The result is fantastic. A page that took 3 minutes to laod
from the US site downloads in 15 seconds from the UK site,
because it didn't have to negotiate the bottleneck of the
transatlantic cable. And even the unpopular pages on the other
side are faster because there is less overall traffic through
the bottleneck.
It is unlikely that US traffic to the UK BBS ever travels on
the JANET cable, but the other transatlantic links are finite
in number and capacity. As the cable cost is not DIRECTLY passed
to you there is no financial reason for you (unlike me, part of
a university that more directly funds a transatlantic cable)
to avoid overseas web sites. There are, of course other reasons
for using mirrors. If you are selfish, you will like the fact
that the most local mirror will load much faster than the more
distant source of the same information. If you are altruistic
you will like the fact that your use of a more local mirror
allows other peoples' transatlantic information exchange to
happen faster.
There are other reasons to mirror information. Many ISP's have
a stepped charge based upon the amount of bandwidth used, or
else have a restriction that customers are not to exceed some
bandwidth threshold. Drawing some proportion of traffic to a
mirror can help to keep the bandwidth below threshold. Often
pages will be mirrored just to speed up loading times -- as
a convenience rather than as a cost-saving measure.
Many web pages automatically redirect you, so it is sometimes
hard to know what place the content originates from. If the
UK BBS member pages are all on the UK server I wouldn't worry
about it, but I would use the 'local' server for non-sign-in
pages if they load faster.
Douglas McKinnie
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