In a TCP/IP network, every OSI Layer 2 protocols work with IP at OSI Layer 3. but, the Layer 2 protocol used depends on the logical topology and the physical media.
every protocol performs media access control for specific Layer 2 logical topologies. This means that a number of different network devices can work as nodes that operate at the data link layer while implementing these protocols. These devices contain the NICs on computers as well as the interfaces between routers and Layer 2 switches.
The Layer 2 protocols used for a particular network topology is determined by the equipment used to apply that topology. The technology is, in turn, determined by the size of the network – in terms of the number of hosts and the geographic scope – and the services to be provided over the network.
A LAN usually uses a high-bandwidth technology that is able of supporting huge figures of hosts. A LAN’s moderately small geographic area (a single building or a multi-building campus) and its high density of users, make this technology cost-effective.
on the other hand, WANs cover a large geographical area, using a high bandwidth technology is usually not cost-effective for WANs. The cost of the long distance physical links and the technology used to carry the signals over those distances typically results in lower bandwidth capacity. Traditionally, WANs have been implemented using one of two technologies: circuit switching and packet switching. Recently, frame relay and ATM networks have assumed major roles. The differentiation in bandwidth usually results in the use of different protocols for LANs and WANs.
Data link layer protocols
Point-to-Point Protocol (PPP)
Click to view LAN and WAN Frame Demo