Cisco Systems 3.2 manual Cisco Wireless LAN Controller Memory

Chapter 1 Overview

Wireless LAN Controller Platforms

•Enables and/or disables the 802.11a, 802.11b and 802.11g Cisco 1000 series lightweight access point networks.

•Enables or disables Radio Resource Management (RRM).

To use the Startup Wizard, refer to the “Using the Configuration Wizard” section on page 4-2.

Cisco Wireless LAN Controller Memory

The Cisco Wireless LAN Controller contain two kinds of memory: volatile RAM, which holds the current, active Cisco Wireless LAN Controller configuration, and NVRAM (non-volatile RAM), which holds the reboot configuration. When you are configuring the operating system in a Cisco Wireless LAN Controller, you are modifying volatile RAM; you must save the configuration from the volatile RAM to the NVRAM to ensure that the Cisco Wireless LAN Controller reboots in the current configuration.

Knowing which memory you are modifying is important when you are:

•Using the Configuration Wizard

•Clearing the Controller Configuration

•Saving Configurations

•Resetting the Controller

•Logging Out of the CLI

Cisco Wireless LAN Controller Failover Protection

Each Cisco Wireless LAN Controller has a defined number of communication ports for Cisco 1000 series lightweight access points. This means that when multiple controllers with unused access point ports are deployed on the same network, if one controller fails, the dropped access points automatically poll for unused controller ports and associate with them.

During installation, Cisco recommends that you connect all lightweight access points to a dedicated controller, and configure each lightweight access point for final operation. This step configures each lightweight access point for a primary, secondary, and tertiary controller, and allows it to store the configured WLAN Solution Mobility Group information.

During failover recovery, the configured lightweight access points obtain an IP address from the local DHCP server (only in Layer 3 Operation), attempt to contact their primary, secondary, and tertiary controllers, and then attempt to contact the IP addresses of the other controllers in the Mobility group. This prevents the access points from spending time sending out blind polling messages, resulting in a faster recovery period.

In multiple-controller deployments, this means that if one controller fails, its dropped access points reboot and do the following under direction of the Radio Resource Management (RRM):

•Obtain an IP address from a local DHCP server (one on the local subnet).

•If the Cisco 1000 series lightweight access point has a primary, secondary, and tertiary controller assigned, it attempts to associate with that controller.

•If the access point has no primary, secondary, or tertiary controllers assigned or if its primary, secondary, or tertiary controllers are unavailable, it attempts to associate with a master controller on the same subnet.

Cisco Wireless LAN Controller Configuration Guide

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