Internetworking is the technology that makes it possible to interconnect many disparate physical networks with diverse underlying hardware technologies and make them function as a coordinated unit. The internetworking/internet technology hides the details of network hardware and permits computers to communicate independent of their physical network connections. When we speak of internetworking technology, we speak of internet technology in particular.

The internet technology put forward by DARPA (Defense Advanced Research Projects Agency) was the first effort towards implementing internetworking technology as the Internet connecting a group of computer networks for research purposes. The official protocol suite designed for implementing the Internet technology was the TCP/IP protocol/Internet protocol.

TCP/IP internet provides a variety of services for the users connected to the internet. Since TCP/IP are higher level protocols, they allows programmers to quickly create data communication programs, sessions and configurations to setup the required services without caring about the underlying hardware details or other hardware configurations.

Application level Internet services via TCP/IP

TCP/IP internet from the user’s point of view, is a set of application programs that use the network to carry out useful communication tasks while providing specific application level services such as email, file transfer and remote login. Email via TCP/IP is a reliable, secured and cost effective means of transferring electronic mails between 2 users in the internet, FTP via TCP/IP enables file transfer between two remote machines in the internet. Remote login or Telnet application via TCP/IP enables a user sitting at one computer to connect to a remote machine and establish an interactive login session with each other.

Network level Internet services via TCP/IP

The 2 major network level internet services via TCP/IP are as follows-

 Connectionless Packet Delivery Service  forms the basis for all other internet services and is basically a packet switched service. The TCP/IP routes the small message packets according to the destination address. Since the packets are dynamically routed, the resulting connectionless service routes each packet separately and doesn’t ensure reliable in-order delivery. Such as service is unreliable since the network does not respond to the sender or receiver about packet mis-delivery, delay, deprecation etc since the Internet software attempts an earnest delivery of packets.

Reliable Stream Transport Service ensure reliable logical connection between two communicating machines over the Internet that uses a handshake mode of communication.