H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 734)

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Client information backup
In a network environment as shown in Figure 466 , to prevent clients from going offline due to unexpected
primary/backup AC switchover, the ACs must support the stateful failover function. This feature enables
the primary AC to send client information in real time to the backup AC through an IACTP tunnel,
ensuring consistency of client information on the two ACs. When a switchover occurs, the backup AC
immediately takes over services for online clients to ensure service continuity.
For stateful failover to operate correctly, configure client information backup on both the primary and
backup ACs so that the client information on both ACs are identical.
This feature supports backing up information for clients that use 802.1X authentication and clients that
use clear-type wireless services.
Figure 745 Network diagram
As shown in Figure 466 , AC 1 and AC 2 back up each other. AC 1 is the primary AC of AP 1, AC 2 is
the primary AC of AP 1, and the two ACs are in the same IACTP tunnel. When clients go online and
offline or roam between the ACs, the two ACs synchronized client information in real time to ensure
consistent client information.
If an anomaly occurs, for example, AC 1 fails, the tunnel between AC 1 and AP 1 is terminated, or AC
2 detects that the tunnel to AC 1 is terminated, AC 2 becomes the primary AC of AP 1. During the switch,
clients connected with AP 1 are not logged off. When the network recovers, AC 2 sends all client
information to AC 1 to ensure consistent client information.
NOTE:
If a primary/backup AC switchover occurs during the client information backup process, clients will be
logged out and associated with the AC again because the backup AC does not have complete online client
information.
To identify consistency of client information, use the following ways: