Specifications

BPG_11n_v1.0 | Page 21
Redundant Controllers via DNS
Another way of implementing controller redundancy is with the help of DNS. This method is
often preferred as it is simple to configure. The following shows how to set things up on the
DNS.
DNS entry wlan-controller = primary controller
DNS entry wlan-controller2 = secondary controller
RF Redundancy
RF Redundancy is built into the typical Vcell deployment. If you recall we previously stated
that at each location 2 or 3 be visible. If this practice is followed we could lose an AP
anywhere and still provide pervasive wireless service. For additional layers of RF redundancy
more radios per location can be added.
High Client Density Deployments
Some examples of high client density deployments are auditoriums, stadiums, cafeterias,
intensive care units.
The ability to provide enough capacity for high client density deployments is one of the
strengths of the Meru architecture. As client density scales we can add channel layers.
Anytime high client densities exist consider channel layer with load balancing enabled.
As mentioned previously, virtual port has unique Beacon streams for each client. In high
density deployments these beacon streams can consume a considerable portion of available
channel bandwidth. To lessen the impact on channel usage of beacon stream we should
remove 1-2 Mb/sec base rates on the ESS profiles. This way beacons are transmitted at
higher data rates, which results in less time consumed for management overhead.
In the simplest form of channel layering it is just a matter of deploying dual radio APs and
applying the ESS profiles to both radios. By doing this we have two channels – one in 2.4GHz
and one in 5GHz -- where all services are present. If service is disrupted on either channel due
to a local source of interference (e.g. microwave oven) there is another channel available.
This approach has limitation. For instance, load balancing does not work across spectrums.
Additionally, some clients do not support both bands.
Load Balancing with Channel Layering
As mentioned previously Meru Networks WLAN systems have the ability to use channel
layering to provide additional capacity where needed.
Another feature available is Load Balancing (LB). With LB clients are evenly distributed across
all available channels (within a given spectrum).
For this type of LB to work two or more APs must be co-located. These APs need to be placed
approximately 7 – 10 ‘’ apart.
MERU BEST PRACTICES GUIDE | 11n Design, Implementation and Optimization