In a LAN environment, the access layer grants end devices access to the network. In the WAN environment, it may provide teleworkers or remote sites access to the corporate network across WAN connections.
As shown in the figure, the access layer for a small business network generally incorporates Layer 2 switches and access points providing connectivity between workstations and servers.
The access layer serves a number of functions including:
- Layer 2 switching
- High availability
- Port security
- QoS classification and marking and trust boundaries
- Address Resolution Protocol (ARP) inspection
- Virtual Access Control Lists (VACLs)
- Spanning tree
- Power over Ethernet (PoE) and auxiliary VLANs for VoIP