Trusted Network Detection (TND) gives you the ability to have AnyConnect automatically disconnect a VPN connection when the user is inside the corporate network (the trusted network) and start the VPN connection when the user is outside the corporate network (the untrusted network).
https://www.cisco.com/c/en/us/td/docs/security/vpn_client/anyconnect/anyconnect41/administrati on/guide/b_AnyConnect_Administrator_Guide_4-1/configure-vpn.html#id_100236