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Networking is the name given to the technology that makes the Internet work.
It's the ability for computers to communicate with each other to allow the sharing
of information or resources.
Basic TCP/IP
TCP/IP is an abbreviation for Transmission Control Protocol / Internet Protocol.
It is a set of protocols that define how two or more computers can communicate
with each other. This is a set of rules that describe how the data is passed
between the computers. The protocol is an open description of how to write the
software so that it can be developed for use on any type of computer. Within
the TCP/IP networking protocol there are lots more protocols. These provide
different functions as part of the networking. These can be integral to the
operation of the networking, such as the Domain Name System or could be an application
that uses the network such as E-mail.
TCP/IP is not limited to a certain computer, it is an open protocol that independence
from any particular operating system. A heterogeneous network can therefore
be created consisting of any combination of UNIX, Windows, Apple or OS/2, OS390
(plus any other) computers. We will also be covering UDP (User Datagram Protocol).
This often goes alongside TCP. The main difference is that TCP is connection
based protocol whereas UDP is connectionless. In other words when TCP is being
used there is a session setup between the hosts and the transfer is guaranteed.
This compares with UDP where the data is sent but there is no checking that
it has been received.
A common way of comparing these is to liken TCP to the telephone system and
UDP to the Postal system. With the telephone when you establish a connection
with the other person, you know for certain that the user receives the message.
If you were disconnected during the telephone conversation then you would know
about it and be able to phone the other person again. With the postal system
after you post the letter then you do not know for certain whether or not the
mail will be received. After you have posted the letter it could be lost or
destroyed on it’s way to it’s destination. Or if the person has
moved house they may never receive the letter.
At first it may sound that there is no reason to choose UDP over TCP after
all if you can have the extra reassurance then why would you care about UDP.
The reason for this is that there is a lot of overhead involved in TCP. For
each data being sent a confirmation has to be generated and even if there is
no data being sent there will normally be some kind of keep alive signal. Whereas
for some less important data you may just want to send and forget it with the
hope it will reach the other end. Some applications even add their own checking
on top of the UDP protocol to overcome the problems associated with it being
a connectionless protocol.
OSI Model
Networking protocols are often described relating to the OSI model. The OSI
model splits the different functions of networking into different layers. By
describing the networking protocols in layers it allows the layer to be changed
without affecting other layers.
The networking models are particularly useful in that it allows the protocol
to be
implemented on any system. Allowing UNIX computers to talk as a peer with PC’s
or even mainframes.
Keep reading?
More information is in the PenguinTutor Tutorial - Basic TCP/IP Networking Reference Guide.
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