TCP/IP Protocol stack

                                TCP/IP  Protocol stack

The TCP/IP suite is a layered model similar to the OSI reference model. Its name is actually a combination of two individual protocols.  Transmission Control Protocol  (TCP) and Internet Protocol  (IP) .  Although the OSI reference model is universally recognized, the historical and technical open standard of the internet is the TCP/IP protocol stack.

TCP/IP protocol stack has four layers. Note  that some of the layers in the  TCP/IP protocol stack have same names as layers in the  OSI layer, the layers have different functions in each model..

1.     Application  Layer

2.     Transport  Layer

3.     Internet  Layer

4.     Network Access Layer

1 1.   APPLICATION LAYER    { Protocols }

The application layer handles high level protocols, including issues of representation, encoding, and dialog   control . The TCP/IP model combines all application related issues into one layer and ensures that this data is properly packaged for the next layer.

Eg :

v  HTTP

v  POP3

v  SMTP

  2.     TRANSPORT LAYER   { Protocols }

The Transport layer deals with QoS (Quality of Service) issues of reliability, flow control and error correction. One of the its protocols, TCP ,provides for reliable network communication

v  TCP

v  UDP

 3.     INTERNET   LAYER   {Networks}

The purpose of the Internet layer is to send source data grams  any network on the internetwork and have them arrive at the destination, regardless of the path they look to get the  there .

v  IP

 4.     NETWORK ACCESS LAYER  {Networks}

The name of this layer is broad and somewhat confusing .It is also called the host-to-network layer. It includes the LAN and WAN protocol sand all the details in the OSI physical and data link layers.

v  Ethernet

v  Frame Relay

The differences that exist between the TCP/ip  protocol  stack and the OSI reference model includes the followings :

1    1.    TCP/IP combines  the presentation and session layer into application layer .

     2.     TCP/ip   combines  the OSI data link and physical layer into the network access    

      layer.

                    TCP/IP Stack Model – Example Devices & Protocol