Users Guide

Dell PowerConnect ArubaOS 5.0 | User Guide Adding Local Controllers | 393
Chapter 18
Adding Local Controllers
This chapter explains how to expand your network by adding a local controller to a master controller
configuration. Typically, this is the first expansion of a network with just one controller (which is a master
controller). This chapter is a basic discussion of creating master-local controller configurations. More complicated
multi-controller configurations are discussed in other chapters.
This chapter describes the following topics:
z “Moving to a Multi-Controller Environment” on page393
z “Configuring Local Controllers” on page395
Moving to a Multi-Controller Environment
For a single WLAN configuration, the master controller is the controller which controls the RF and security
settings of the WLAN. Additional controllers to the same WLAN serve as local switches to the master controller.
The local controller operates independently of the master controller and depends on the master controller only
for its security and RF settings. You configure the layer-2 and layer-3 settings on the local controller independent
of the master controller. The local controller needs to have connectivity to the master controller at all times to
ensure that any changes on the master are propagated to the local controller.
Some of the common reasons to move from a single to a multi-controller-environment include:
z Scaling to include a larger coverage area
z Setting up remote Access Points (APs)
z Network setup requires APs to be redistributed from a single controller to multiple controllers
Preshared Key for Inter-Controller Communication
A preshared key (PSK) is used to create IPSec tunnels between a master and backup master controllers and
between master and local controllers. These inter-controller IPSec tunnels carry management traffic such as
mobility, configuration, and master-local information.
There is a default PSK to allow inter-controller communications, however, for security you need to configure a a
unique PSK for each controller pair. See“Best Security Practices for the Preshared Key” on page394. You can use
either the WebUI or CLI to configure a 6-64 character PSK on master and local controllers.
To configure a unique PSK for each controller pair, you must configure the master controller with the IP address
of the local and the PSK, and configure the local controller with the IP address of the master and the PSK.
You can configure a global PSK for all master-local communications, although this is not recommended for
networks with more than two controllers. See “Best Security Practices for the Preshared Key” on page394. On
the master controller, use 0.0.0.0 for the IP address of the local. On the local controller, configure the IP address
of the master and the PSK.
The local controller can be located behind a NAT device or over the Internet. On the local controller, when you
specify the IP address of the master controller, use the public IP address for the master.
Note: An inter-controller IPSec tunnel can be used to route data between networks attached to the controllers if you have
installed PEFV licenses in the controllers. To route traffic, configure a static route on each controller specifying the destination
network and the name of the IPSec tunnel.