Internet Layer

The Internet Layer of the TCP/IP architecture model resides just above the Network Access Layer and below the Transport Layer. The primary concern of the protocol at this layer is to manage the connections across networks as information is passed from source to destination. The Internet Protocol (IP) is the primary protocol at this layer of the TCP/IP architecture model. The Internet Protocol, defined by RFC 791, is the core of TCP/IP. It provides the packet delivery system on which all TCP/IP networking is based. All information that flows through TCP/IP networks passes through IP. IP is a connectionless protocol. This means it does not use a handshake to provide end-to-end control of communications flow. It relies on other layers to provide this function if it is required. IP also relies on other layers to provide error detection and correction. Because of this IP is sometimes referred to as an unreliable protocol. This does not mean that IP cannot be relied upon to accurately deliver data across a network, it simply means that IP itself does not perform the error checking and correcting functions. The functions that IP performs include: Defining a datagram and an addressing scheme Moving data between transport layer and network access layer protocols Routing datagrams to remote hosts The fragmentation and reassembly of datagrams The only other protocol that is generally described as being at the Internet Layer of the TCP/IP model is the Internet Control Message Protocol (ICMP), a protocol used to communicate control messages between IP systems.