H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 40)

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Configuring stateful failover
NOTE:
Support for the stateful failover feature may vary depending on your device model. For more information,
see
About the WX Series Access Controllers Configuration Guides.
Stateful failover overview
Some customers require the key entries or access points of their networks, such as the Internet access
point of an enterprise or a database server of a bank, to be highly reliable to ensure continuous data
transmission. Deploying only one device (even with high reliability) in such a network risks a single point
of failure and cannot meet the requirement, as shown in Figure 13 .
Figure 13 Network with one device deployed
Operating procedure
The stateful failover feature was introduced to meet the requirement. Stateful failover involves service
backup and traffic switchover. The operating procedure of stateful failover is as follows:
1. As shown in Figure 14 , Device A and Device B connects to each other over a failover link.
2. The two devices exchange state negotiation messages periodically through the failover link. After
the two devices enter the synchronized state, they back up the sessions of each other to make sure
that the sessions on them are consistent.
3. If one device fails, the other device can take over the services by using VRRP to avoid service
interruption.
In this document, the stateful failover feature supports backing up portal and DHCP services.