Summary

This chapter discussed how to use VLANs to create logically separate LANs on the same physical switch. VLANs also are used to group physically separate LANs so that they behave as though they are on the same physical network segment (wire). Each switch port switch is assigned to a VLAN. For the Cisco Catalyst, VLAN operation is performed at Layer-2 (OSI Model Data-Link Layer), requiring a Layer-3 (Network) device, such as a router, to move traffic between VLANs.

These are the benefits of using VLANs over traditional LAN implementations. These include the formation of virtual workgroups, reduced cost of handling user moves and changes, increased performance, and enhanced security.

Port-based VLANs, MAC address-based VLANs, and Layer-3 VLANs are used to establish membership to a VLAN. For port-based VLANs, the administrator assigns each port of a switch to a VLAN; for MAC address-based VLANs, the source or desination MAC (hardware address) defined the membership; and finally, for Layer-3 VLANs, the membership is based on the Layer-3 (Network) address of the host.