H3C Technologies H3C SecBlade LB Cards - Manual (Page 82)

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Configuring stateful failover
The term "router" in this document refers to both routers and LB products.
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 in such a network, even with high reliability, risks a single point
of failure. Therefore, it cannot meet the requirement, as shown in Figure 33 .
Figure 33 Network with one device deployed
The stateful failover feature was introduced to meet the requirement. Two devices enabled with stateful
failover can back up services such as NAT, ALG, blacklist, and load balancing, and synchronize
configurations through a failover link.
The failover link transmits only state negotiation messages and backup data.