Network Protocols

In computer  networks  communication  occurs between  the entities in different  systems an entity  is anything  that is  capable  of sending  or receiving  messages. However  two  entities will  not simply  send bit streams to each  other but expected to  be understand  those bit streams, for  communications  to occurs the entities must  agree on a protocol. A protocol is a set  of rules  that  govern  data  communications. A protocol  defines what  is communicated how  it is communicated and when  it is  communicated.

The exchange  of messages  and the actions takes  when  these  message sent  and received are the key  defining  elements  of a protocol.

A protocol  defines  the formal  and the order of messages exchanged between  two  or more  communicating  entities as well  as the actions  taken on the  transmission and  or receipt of a message  or other event.

As an example  of a computer  network  protocol with which  one is  probably  familiar consider what happens  when one  will make a request to  a web server that is  when one  type the  URL ( Uniform Resource Locator) or  a web page into the web browser. First the computer will send  a connection request  message to  the web server and wait  for a reply. The web server will  eventually receive the connection request message  and return connection  reply message. Knowing that it is  now ok to request the web document. The computer  then sends  the name  of the  web page which  is needed to  fetch from that web  server in a GET message. Finally  the web  returns  the web  page  to the  computer.

The internet and computer  networks  in general  make  extensive use of protocols. Different  protocols are  used to  accomplish  different  communication  task.

Protocol are divided  into two categories  based on their use of connections.