Dual-link cold backup allows two ACs on an AC + Fit AP network to manage APs simultaneously. The APs set up CAPWAP links with both ACs, between which one AC functions as the active AC to provide services for the APs while the other works as the standby AC. When the active AC fails or the CAPWAP link between the active AC and AP become faulty, the standby AC replaces the active AC to manage APs and provide services. To ensure that both ACs provide the same services, it is recommended that the same service configurations be performed on the active and standby ACs.
Usually, an AC controls and manages massive APs and STAs on an AC + Fit AP network. Once the CAPWAP link between the AC and AP is disconnected, the AC is unable to provide services for STAs. Dual-link cold backup reduces the impact of a CAPWAP link failure on the STAs, improving network reliability.