Liveness detection for captive portal

You can configure a keep-alive timer to extend a captive portal authentication session after the MAC table aging timer expires. The keep-alive timer starts when the MAC address of the authenticated host ages of out of the Ethernet switching table. If traffic is received within the keep-alive period, the timer stops and the authenticated session remains active. If there is no traffic within the keep-alive period, the authenticated session ends, and the host must re-authenticate.