VPN
certificate differnce connections method active active bgp tunnel type OPENVPN(SSL) SSTP IKEV2 OPEN VPN is protcol foropen source , its require thried party software to configure it. Its open source does not have any standard IKEV2 is more advanced version protocol it has a function of reconnection , Its does not require any software IKv2 is a standard described rfc-7296 Its work with mobile client as weell