User's Guide

Table Of Contents
hwc_fastfailover.fm
Availability and session availability
Session availability
9034530-02,
March 2010
HiPath Wireless Controller, Access Points and Convergence Software V7.11, User Guide 393
The secondary HiPath Wireless Controller does not have to detect its link failure
with the primary HiPath Wireless Controller for the session availability to kick in.
If the Wireless AP loses five consecutive polls to the primary controller either due
to the controller outage or connectivity failure, it fails over to the secondary
controller fast enough to maintain the user session.
In session availability mode, the Wireless APs connect to both the primary and
secondary HiPath Wireless Controllers. While the connectivity to the primary
HiPath Wireless Controller is via the “active” tunnel, the connectivity to the
secondary HiPath Wireless Controller is via the “backup” tunnel.
Figure 26 Session availability mode
The following is the traffic flow of the topology illustrated in Figure 26:
The Wireless AP establishes the active tunnel to connect to the primary
HiPath Wireless Controller.
The HiPath Wireless Controller sends the configuration to the Wireless AP.
This configuration also contains the port information of the secondary HiPath
Wireless Controller.
On the basis of the secondary HiPath Wireless Controller’s port information,
the Wireless AP connects to the secondary controller via the backup tunnel.
After the connection is established via the backup tunnel, the secondary
HiPath Wireless Controller sends the backup configuration to the Wireless
AP.
The Wireless AP receives the backup configuration and stores it in its
memory to use it for failing over to the secondary controller. All this while, the
Wireless AP is connected to the primary HiPath Wireless Controller via the
‘active’ tunnel.
Primary Controller
Secondary Controller
Wireless AP