Cisco Cisco Access Registrar 4.2 Especificaciones descargar pdf (Pagina 44)

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Cisco Wireless LAN Controller Configuration Guide

OL-13826-01

Chapter 1 Overview

Cisco Wireless LAN Controller Memory

The controller contains two kinds of memory: volatile RAM, which holds the current, active controller

configuration, and NVRAM (non-volatile RAM), which holds the reboot configuration. When you are

configuring the operating system in controller, you are modifying volatile RAM; you must save the

configuration from the volatile RAM to the NVRAM to ensure that the 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 controller has a defined number of communication ports for 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 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 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.

• If the access point finds no master controller on the same subnet, it attempts to contact stored

mobility group members by IP address.

• Should none of the mobility group members be available, and if the lightweight access point has no

primary, secondary, and tertiary controllers assigned and there is no master controller active, it

attempts to associate with the least-loaded controller on the same subnet to respond to its discovery

messages with unused ports.

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