User's Manual

10/10/03 Airespace Switch and Appliance Failover Protection
90-100584-004 Airespace Product Guide 38
Airespace Switch and Appliance Failover ProtectionAirespace Switch and Appliance Failover Protection
Each Airespace Wireless Switch and WLAN Appliance with front-panel 10/100Base-T ports can normally
associate with as many primary Airespace APs as it has physical ports. Thus, a 12-port 4012 Airespace
Wireless Switch can associate with 12 primary Airespace APs, and a 24-port 4024 Airespace Wireless
Switch can associate with 24 primary Airespace APs.
However, each 4012 and 4024 Airespace Wireless Switch can also associate with as many secondary
Airespace APs as it has physical ports. Thus, a 12-port 4012 Airespace Wireless Switch can associate
with 24 Airespace APs (12 primary and 12 secondary), and a 24-port 4024 Airespace Wireless Switch
can associate with 48 Airespace APs (24 primary and 24 secondary).
Model 4101 and 4102 Airespace WLAN Appliances can associate with up to 36 Airespace APs, and have
no front-panel 10/100Base-T ports. Note that the 4101 and 4102 Airespace WLAN Appliances associate
with 36 primary Airespace APs and no secondary Airespace APs.
In a multiple-Airespace Switch and Appliance system (refer to Multiple-Airespace Switch and Appliance
Deployments), this means that if one Airespace Switch or Appliance fails, its dropped Airespace APs
immediately do the following under direction of the AireWave Director Software
:
• If the Airespace AP has a Primary Airespace Switch or Appliance assigned, it attempts to
associate with that Airespace Switch or Appliance.
• If the Airespace AP has no Primary Airespace Switch or Appliance assigned or if its Primary
Airespace Switch or Appliance is unavailable, it attempts to associate with a Master Airespace
Switch or Appliance on the same subnet.
• If the Airespace AP has no Primary Airespace Switch or Appliance assigned and there is no
Master Airespace Switch or Appliance active, it attempts to associate with the least-loaded
Airespace Switch or Appliance on the same subnet to respond with unused primary or
secondary ports.
This means that when sufficient Airespace Switches and Appliances are deployed in Appliance Mode,
should one Airespace Switch or Appliance fail, active Airespace AP client sessions are momentarily
dropped while the dropped Airespace AP associates with an unused port on another Airespace Switch or
Appliance, allowing the client device to immediately reassociate and reauthenticate.
Because the Airespace APs and/or third-party APs plug into the front of the Airespace Wireless Switch
when it is deployed in Direct Connect Mode
, Airespace Switch and Appliance failover protection is not
supported for Airespace APs in Direct Connect Mode.