TCP/IP Protocol Stack

Introduction › CA XCOM Data Transport in the TCP/IP Network › TCP/IP Protocol Stack

TCP/IP Protocol Stack

TCP/IP is a collection of specialized communications protocols and functions organized into a stack of four layers. The layers that make up the TCP/IP protocol stack are the following:

Network layer (the lowest protocol layer)
Internetwork layer
Transport layer
Application layer (the highest protocol layer)

Each layer in the TCP/IP protocol stack provides services to the layer above it and uses the services below it.

The table below lists the protocols and functions that form the content of each layer of the TCP/IP protocol stack (the table shows only partial contents for the top and bottom layer).

TCP/IP Protocol Layer	Protocols and Functions
Network layer	Token Ring Ethernet X.25 etc.
Internetwork layer	Internet Protocol (IP) Control Message Protocol (ICMP) Address Resolution Protocol (ARP)
Transport layer	Transmission Control Protocol (TCP) User Datagram Protocol (UDP)
Application layer	Telnet File Transfer Protocol (FTP) Simple Mail Transfer Protocol (SMTP) Domain Name System (DNS) Sockets etc.

The next few sections provide (1) a summary of the services that each layer of the protocol stack performs in the TCP/IP network and (2) a description of the protocols that are particularly important for the functioning of CA XCOM Data Transport as a TCP/IP network node.