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The TCP/IP Guide  9  TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4)

TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4) 1 TCP/IP Serial Line Internet Protocol (SLIP) and Point-to-Point Protocol (PPP)

The lowest layer of the OSI Reference Model is the physical layer, which is responsible for the "nitty gritty" details of transmitting information from one place to another on a network. The layer just above the physical layer is the data link layer, called the network interface layer or just the link layer in the TCP/IP architectural model. Its primary job is to implement networks at the local level, and to interface between the hardware-oriented physical layer, and the more abstract, software-oriented functions of the network layer and those above it.

In this section I provide a description of the two protocols that reside at the data link or network interface layer in the TCP/IP protocol suite. These are the Serial Line Internet Protocol (SLIP) and the Point-to-Point Protocol (PPP). They are both discussed in a single subsection below this one. (The reason why this section contains only one subsection is that the TCP/IP Guide is part of a larger networking reference that contains coverage for many more technologies and protocols at this layer.)

TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4) 1 TCP/IP Serial Line Internet Protocol (SLIP) and Point-to-Point Protocol (PPP)