Specifications

BPG_11n_v1.0 | Page 20
Four key characteristics of the N+1 redundancy model are as follows:
1. Slave and Master controllers that make up the N+1 cluster must all reside on the
same IP network so the slave controller can gratuitously ARP on behalf of the IP
address for the master controller for which it is providing backup services
2. APs must be a layer 3 hop away from their redundant controller cluster when N > 1
3. Master to Slave configurations are synchronized each time configurations are saved
via Web interface or CLI session.
4. When a slave controller is active, meaning it is actively providing +1 backup services
for one of the masters in the cluster, monitoring of the other masters if applicable
(where N > 1) will be put on hold until the master for which it is providing backup
services has rejoined the cluster and assumed production services.
AP PROVISIONED REDUNDANCY
Meru Networks AP Primary/Secondary controller redundancy option allows Meru access
points to be configured with a primary and secondary controller, should the primary
controller stop responding the APs they then connects to their configured secondary
controller via a DNS resolvable host name or IP address provided by DHCP option 43 vendor
specified attribute.
Three key characteristics of the AP Primary/Secondary controller model are as follows:
1. The primary and secondary controllers can be deployed on diverse IP networks (I. e.,
across Metro Ethernet networks or WAN services)
2. APs must be a layer 3 hop away from their redundant controller
3. Configuration changes between primary and secondary controllers must be manually
kept in sync
Redundant Controllers Configured via Option 43
AP can get controller assignment from a DHCP server. This method of controller assignment
is accomplished by using the Option 43 feature in the DHCP server.
Configuration of Option 43 on the DHCP server is basically the same as when only a single
controller is configured. The difference is that when the second controller is added it needs to
be delimited from the first controller by the use of a single comma (e.g.
192.168.1.1,192.168.1.2). Note that there are no spaces between the controller IP addresses or
the comma.
It should also be noted that there is no way to configure multiple controllers from the CLI or
the GUI. Option 43 is the only way to configure two controllers for the AP. The maximum
number of controllers configurable is two.
Caution: APs that are configured with redundant controllers via Option 43 will continually poll
for their primary controller (i. e., the first controller listed). If that controller becomes
reachable again the APs will reboot and connect back to the primary controller.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization