IPSEC VTI stands for IP Security Virtual Tunnel Interface. It is a method to configure site-to-site IPsec VPNs using a tunnel interface instead of access lists and crypto maps. IPSEC VTI simplifies the configuration and management of IPsec VPNs, supports multicast traffic, and enables routing protocols to run over the VPN.
IPSEC VTI has two types: static and dynamic. Static VTI uses a fixed IP address for the tunnel interface and requires manual configuration of the tunnel parameters. Dynamic VTI uses a dynamic IP address for the tunnel interface and allows automatic creation and deletion of the tunnel based on the IKE (Internet Key Exchange) negotiation.
IPSEC VTI is supported by Cisco IOS and other vendors. It is compatible with various encryption algorithms, authentication methods, and IKE versions. It can also integrate with other features and functions, such as QoS (Quality of Service), firewall, GRE (Generic Routing Encapsulation), etc.