Cisco Systems 3.2 manual Using Link Aggregation, Using Multiple AP-Manager Interfaces

Chapter 3 Configuring Ports and Interfaces

Configuring a 4400 Series Controller to Support More Than 48 Access Points

The following factors should help you decide which method to use if your controller is set for Layer 3 operation:

•With link aggregation, all of the controller ports need to connect to the same neighbor switch. If the neighbor switch goes down, the controller loses connectivity.

•With multiple AP-manager interfaces, you can connect your ports to different neighbor devices. If one of the neighbor switches goes down, the controller still has connectivity. However, using multiple AP-manager interfaces presents certain challenges (as discussed in the “Using Multiple AP-Manager Interfaces” section below) when port redundancy is a concern.

Using Link Aggregation

See the “Enabling Link Aggregation” section on page 3-27for more information and instructions on enabling link aggregation.

Note Link aggregation is the only method that can be used for the Cisco WiSM controllers.

Using Multiple AP-Manager Interfaces

Note This method can be used only with Cisco 4400 series stand-alone controllers.

When you create two or more AP-manager interfaces, each one is mapped to a different port (see Figure 3-14). The ports should be configured in sequential order such that AP-manager interface 2 is on port 2, AP-manager interface 3 is on port 3, and AP-manager interface 4 is on port 4. In addition, all AP-manager interfaces must be on the same VLAN or IP subnet, and they may or may not be on the same VLAN or IP subnet as the management interface.

Note You must assign an AP-manager interface to each port on the controller.

Before an access point joins a controller, it sends out a discovery request. From the discovery response that it receives, the access point can tell the number of AP-manager interfaces on the controller and the number of access points on each AP-manager interface. The access point generally joins the AP-manager with the least number of access points. In this way, the access point load is dynamically distributed across the multiple AP-manager interfaces.

Note Access points may not be distributed completely evenly across all of the AP-manager interfaces, but a certain level of load balancing occurs.

Cisco Wireless LAN Controller Configuration Guide

OL-8335-02 3-31