In information technology, a protocol is the special set of rules that end points in a telecommunication connection use when they communicate. Protocols specify interactions between the communicating entities. Protocols exist at several levels in a telecommunication connection. Protocols are often described in an industry or international standard.
The Internet Protocol (IP) is the principal communications protocol in the internet protocol suit for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet.TCP/IP is the commonly used nickname for the set of network protocols composing the Internet Protocol suite. Many texts use the term "Internet" to describe both the protocol suite and the global wide-area network. To interconnect your TCP/IP network with other networks, you must obtain a unique IP network number. IP network numbers are assigned by an organization known as the InterNIC. If hosts on your network are going to participate in the Internet Domain Name system (DNS), you must obtain and register a unique domain name. The InterNIC also handles the registration of domain names under certain top-level domains such as .com, .edu and .gov.
TCP enables applications to communicate with each other as though connected by a physical circuit. TCP sends data in a form that appears to be transmitted in a character-by-character fashion, rather than as discreet packets. This transmission consists of a starting point, which opens the connection, the entire transmission in byte order, and an ending point, which closes the connection.TCP attaches a header onto the transmitted data. This header contains a large number of parameters that help processes on the sending machine connect to peer processes on the receiving machine.
TCP confirms that a packet has reached its destination by establishing an end-to-end connection between sending and receiving hosts. TCP is therefore considered a "reliable, connection-oriented" protocol.
UDP, the other transport layer protocol, provides datagram delivery service. It does not provide any means of verifying that connection was ever achieved between receiving and sending hosts. Because UDP eliminates the processes of establishing
and verifying connections, applications that send small amounts of data use it rather than TCP.
RIP is implemented by in.routed, the routing daemon, which automatically starts when the machine boots. When run on a router with the option specified, in.routed fills the kernel routing table with a route to every reachable network and advertises "reachability" through all network interfaces.