Link Layer

Overview

The L2 layer in the OSI model refers to the link layer. PDUs at this layer are typically called frames. These are usually variable-sized; the upper bound on how large a frame can be is called the maximum transmission unit (MTU).

The IEEE 802 set of standards defines operations related to local area networks (LANs) and metropolitan area networks (MANs).

Network Interface

A network interface is the point of interconnection between a computer and a network. It can be physical or virtual. A device with multiple network interfaces is said to be multihomed.

A network interface controller, or NIC, is a computer hardware component that connects a computer to a computer network. An NIC is considered a physical layer device as well as a link layer device.