This layer defines the premises layer access or interface to the backbone layer or WAN, and communication between the premises layer (typically LAN) and the backbone (WAN) . An enterprise's application layer might interface the premises layer through the access layer (xDSL) and into the backbone to terminate their application session within the backbone layer.

A typical access device could be a router, L2 switch (FR, ATM, Ethernet), integrated access device (IAD), V.90 modem, XDSL modem, cable modem, PBX, wireless modem, or any device that provides communication between the premises and the backbone.

Protocols supported in this layer typically relate to the network, data-link, and physical layers of the OSIRM, but with the advent of seven-layer switches, sophisticated firewalls, and intrusion-detection devices, can relate to all layers. The separation between the access layer and backbone layers is typically at the router or switch that is shared by the two layers.

The access layer relates to the access and distribution layers of the Cisco model and is responsible for control and segmentation. Control involves security and prioritization of traffic, while segmentation involves managing collision and broadcast domains. The access layer is typically made up of LAN technologies such as Ethernet, Token Ring, FR ATM, xDSL, cable, and wireless, and hard hare such as DXCs, multiplexers, hubs, Layer 2 and 3 switches, and routers.