Application of Dual-Link Cold Backup
1+1 Dual-Link Cold Backup
In the AC+FIT AP network architecture, the AC manages and controls WLAN services for wireless users in a centralized manner. One AC usually controls hundreds of APs and over ten thousand STAs. When a fault occurs on the AC or the link between the AC and AP fails, the services of all users connected to the AC are interrupted. If dual-link cold backup is enabled, the standby AC controls the WLAN services for wireless users when a fault occurs on the active AC or the link between the active AC and AP fails. This reduces service interruption time.
As shown in Figure 1, AC1 and AC2 provide dual links for STAs. AC1 is the active device, serving AP1 and AP2. AC2 is the standby device. Each AP sets up a CAPWAP tunnel with AC1 and AC2 respectively. When the APs detect that AC1 fails, the CAPWAP tunnels between APs and AC2 become the active tunnels, and AC2 becomes the active AC. After AC1 recovers, it becomes the active AC or still functions as the standby AC depending on the configuration.
