The Branch Survivability feature monitors multiple network links between a branch office and Headquarters. I employs the preferred/low-cost link to provide automatic fail-over to operational links
The Branch Survivability module monitors the primary WAN connection, when it detects a failure and if that failure persists for predetermined amount of time, it makes the necessary changes in the routing table to route all IP packets through the 3G/4G network. Additionally, it sends a notification to the IPSec module when fail-over event occurs, so that IPSec can create secure tunnel if necessary. It also sends a notification to the Lync ASM module at the HQ site to modify the bandwidth control on the Lync server(s).