The actual connections between the various networks take a variety of
forms. The most prevalent for Internet links are 56k leased lines
(dedicated telephone lines carrying 56kilobit-per-second connections)
and T1 links (special phone lines with 1Mbps connections). Also
installed are T3 links, acting as backbones between major locations
to carry a massive 45Mbps load of traffic.
These links are paid for by each institution to a local carrier (for
example, Bell Atlantic owns PrepNet, the main provider in
Pennsylvania). Also available are SLIP connections, which carry
Internet traffic (packets) over high-speed modems.
UUCP links are made with modems (for the most part), that run from
1200 baud all the way up to as high as 38.4Kbps. As was mentioned in
The Networks, the connections are of the store-and-forward
variety. Also in use are Internet-based UUCP links (as if things
weren't already confusing enough!). The systems do their UUCP traffic
over TCP/IP connections, which give the UUCP-based network some
blindingly fast "hops," resulting in better connectivity for the
network as a whole. UUCP connections first became popular in the
1970's, and have remained in wide-spread use ever since. Only with
UUCP can Joe Smith correspond with someone across the country or
around the world, for the price of a local telephone call.
BITNET links mostly take the form of 9600bps modems connected from site
to site. Often places have three or more links going; the majority,
however, look to "upstream" sites for their sole link to the network.
"The Glory and the Nothing of a Name"
Byron, {Churchill's Grave}
-----------
Electronic Mail
The desire to communicate is the essence of networking. People have
always wanted to correspond with each other in the fastest way
possible, short of normal conversation. Electronic mail (or
email) is the most prevalent application of this in computer
networking. It allows people to write back and forth without having
to spend much time worrying about how the message actually gets
delivered. As technology grows closer and closer to being a common
part of daily life, the need to understand the many ways it can be
utilized and how it works, at least to some level, is vital.
part of daily life (as has been evidenced by the ISDN effort, the need
to understand the many ways it can be utilized and how it works, at
least to some level, is vital.