IPsec Stateful Failover

B.

Out of the given options, the technology that works with IPsec stateful failover is VRRP (Virtual Router Redundancy Protocol).

IPsec is a protocol used to secure network traffic by encrypting it between two endpoints. IPsec stateful failover refers to the process of automatically transferring the encrypted traffic from one IPsec tunnel to another tunnel on a secondary device in case of a failure on the primary device.

VRRP is a protocol used to provide redundancy for IP networks by allowing multiple routers to share a virtual IP address. This virtual IP address is configured as the default gateway for hosts on the network, and the VRRP routers communicate with each other to determine the active router that will forward traffic to and from the virtual IP address.

When used together, IPsec and VRRP provide a highly available and secure network solution. The primary IPsec tunnel is configured on the active VRRP router, and a secondary IPsec tunnel is configured on the standby VRRP router. If the active VRRP router fails, the standby VRRP router takes over as the active router and the secondary IPsec tunnel is promoted to primary. The IPsec stateful failover mechanism ensures that the encrypted traffic is transferred seamlessly between the primary and secondary tunnels without any interruption.

Option A, GLBP (Gateway Load Balancing Protocol), is a protocol used to provide load balancing and redundancy for IP networks, but it does not support IPsec stateful failover.

Option B, HSRP (Hot Standby Router Protocol), is a protocol similar to VRRP used to provide redundancy for IP networks, but it also does not support IPsec stateful failover.

Option C, GRE (Generic Routing Encapsulation), is a tunneling protocol used to encapsulate one network protocol within another network protocol. While GRE can be used with IPsec to create a secure tunnel, it does not support IPsec stateful failover.

Therefore, the correct answer is D. VRRP.