Distribution layer switches are the aggregation points for multiple access layer switches. The switch must be able to accommodate the total amount of traffic from the access layer devices.

The distribution layer switch must have high performance. The distribution layer switch is a point at which a broadcast domain is delineated. The distribution layer combines VLAN traffic and is a focal point for policy decisions about traffic flow. For these reasons distribution layer switches operate at both Layer 2 and Layer 3 of the OSI model. Switches in this layer are referred to as multilayer switches. These multilayer switches combine the functions of a router and a switch in one device. They are designed to switch traffic to gain higher performance than a standard router. If they do not have an associated router module, then an external router is used for the Layer 3 function.

The following Cisco switches are suitable for the distribution layer: 

• Catalyst 2926G
• Catalyst 5000 family
• Catalyst 6000 family

Interactive Media Activity PhotoZoom: Cisco Catalyst 2950 In this PhotoZoom, the student will view a Cisco Catalyst 2950.

Web Links Cisco Catalyst 4500 Series Switches http://www.cisco.com/en/US/products/ hw/switches/ps4324/index.html