High availability solutions often utilize virtual gateway protocol to avoid single point of failure. We are going to discuss high availability for the IPsec tunnel in the sample topology presented below. In this topology we need to protect traffic between VLAN67 and VLAN58 travelling across VLAN146 segment. In order to accomplish this, we will configure R6 to establish an IPsec tunnel with a virtual gateway representing both R1 and R4.
GLBP, an acronym for Gateway Load Balancing Protocol, is a virtual gateway protocol similar to HSRP and VRRP. However, unlike its little brothers, GLBP is capable of using multiple physical gateways at the same time. As we know, a single HSRP or VRRP group represents one virtual gateway, with single virtual IP and MAC addresses. Only one physical gateway in a standby/redundancy group is responsible for packet forwarding, others remain inactive in standby/backup state. If you have R1, R2, R3...