Typical Application Scenarios for N+1 Backup
N+1 Backup of ACs in Different Network Segments
A large enterprise has branches in different areas. ACs are deployed in the branches to manage APs and provide WLAN access and e-mail services. These services provided on the WLAN require low network reliability and allow temporary service interruption. In this scenario, the enterprise can deploy a high performance AC at the headquarters as a standby AC to provide backup services for active ACs in the branches. This reduces device purchase costs.
As shown in Figure 9-6, ACs of the two branches are on different network segments. AC_1 in branch 1 and AC_2 in branch 2 respectively work as the active AC of AP_1 and AP_2. AC_3 in the headquarters is a high performance AC and serves as the standby AC of AP_1 and AP_2. When the network runs properly, AP_1 and AP_2 sets up a CAPWAP link with AC_1 and AC_2 respectively. When the CAPWAP link on AC_1 or AC_2 fails, AP_1 or AP_2 sets up a CAPWAP link with AC_3. AC_3 replaces AC_1 or AC_2 to provide services for AP_1 or AP_2.
Each AP can establish a CAPWAP link with only one AC at one time.
N+1 Backup of ACs in the Same Network Segment
The waiting hall of an airport accommodates massive users. Multiple ACs manage a large number of APs that provide WLAN access services. These free-of-charge services require low network reliability and allow temporary service interruption. In this situation, a high performance AC can be deployed as a standby AC to provide backup services for other ACs. This reduces device purchase costs.
As shown in Figure 9-7, all ACs are in the same network segment. AC_1 and AC_2 function as the active AC of AP_1 and AP_2 respectively. AC_3 is a high performance AC and works as the standby AC of AP_1 and AP_2. When the network runs properly, AP_1 and AP_2 sets up a CAPWAP link with AC_1 and AC_2 respectively. When the CAPWAP link on AC_1 or AC_2 fails, AP_1 or AP_2 sets up a CAPWAP link with AC_3. AC_3 replaces AC_1 or AC_2 to provide services for AP_1 or AP_2.
Each AP can establish a CAPWAP link with only one AC at one time.
