TCP and IP: Technology Explained

We often hear that the Internet protocol is TCP/IP. Yet this is really a combination of two separate protocols. What are these two protocols, what does each do, and why do we need both?

TCP/IP is actually an entire suite of many protocols.  TCP and IP are simply the two primaries.

Transmission Control Protocol (TCP) is a connection based protocol.  A virtual connection is established between the source and the destination.  Every data packet sent by the host requires that t he recipient send an acknowledgement (ACK).  If success, it send the next packet.  If an error (NACK), it will retransmit the packet until it achieves success.  TCP is used when reliability is essential.  Every data packet must arrive intact at its destination without corruption.  When a person sends a file such as a spreadsheet across a network; the packets will all arrive in good condition and in the proper order.  The receiver can view the file with no problems.  You want not want even a single bit of financial data (or any other file) to be scrambled!

Internet Protocol (IP) is a connectionless protocol.  It is considered less reliable.  However it still offers a very high degree of success.  It simply cannot guarantee that success.  Packets are sent off and no acknowledgement (ACK) is ever needed or requested.  It is simply hoping that the packets will reach their destination.   It is widely used for things like PING, TRACERT, and SMTP (Email) traffic.  Applications such as streaming video can also use IP.  If a PING packet is lost; its no big deal.  If a few frames of a video are lost; its not all that noticeable.  IP is used where speed is more important than reliability.

One of the primary advantages of TCP/IP is the fact that it can be routed.  Earlier protocols such as NETBEUI were not routable.  The packets were thrown on the line and it was up to the correct recipient to grab what it wanted.  Everything event everywhere which caused a great deal of congestion.  With TCP/IP, packets can be routed by using addressing to go from the source to the destination.  Every PC on a network or on the Internet has its own address.  It is very much like having a telephone number or a street address. 

Yes its does get a bit more complicated.  IP address classes, routers, and subnetting all play a part.  Things like DNS are used to make life easier; but these are all separate discussions by themselves.

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