Session Availability

Session availability enables wireless APs to switch over to a standby (backup) wireless appliance fast enough to maintain the mobile user‘s session availability in the following scenarios:

• The primary wireless appliance fails (see AP Failover When Primary Appliance Fails).

  

  AP Failover When Primary Appliance Fails

  

• The wireless AP‘s network connectivity to the primary appliance fails (see AP Failover When Connectivity to Primary Fails).

AP Failover When Connectivity to Primary Fails

The backup ExtremeCloud IQ Controller does not have to detect its link failure with the primary ExtremeCloud IQ Controller for the session availability to kick in. If the AP loses five consecutive polls to the primary ExtremeCloud IQ Controller either due to the ExtremeCloud IQ Controller outage or to connectivity failure, it fails over to the backup ExtremeCloud IQ Controller fast enough to maintain the user session.

In session availability mode (Session Availability Mode), the APs connect to both the primary and backup ExtremeCloud IQ Controller. While the connectivity to the primary ExtremeCloud IQ Controller is via the active tunnel, the connectivity to the backup ExtremeCloud IQ Controller is via the backup tunnel.

Session Availability Mode

The following is the traffic flow of the topology illustrated in Session Availability Mode:

• The AP establishes the active tunnel to connect to the primary ExtremeCloud IQ Controller.
• The ExtremeCloud IQ Controller sends the configuration to the AP. This configuration also contains the port information of the backup ExtremeCloud IQ Controller.
• On the basis of the backup ExtremeCloud IQ Controller port information, the AP connects to the backup ExtremeCloud IQ Controller via the backup tunnel.
• After the connection is established via the backup tunnel, the backup ExtremeCloud IQ Controller sends the backup configuration to the wireless AP.
• The AP receives the backup configuration and stores it in its memory to use it for failing over to the backup ExtremeCloud IQ Controller. During this entire time, the AP is connected to the primary ExtremeCloud IQ Controller via the active tunnel.

Session availability applies only to the following topologies:

• Bridge Traffic Locally at AC
• Bridge Traffic Locally at AP