VRRP: Increasing Reliability and Failover with the Virtual Router Redundance Protocol

11.4. Future of High Availability: Clustering and Beyond

As the need for high availability and high levels of fault tolerance grows, it is imperative that network services and hardware be available at all times, even during upgrades. At the same time, packet processing has moved from simple IP routing to content-based routing and stateful inspection of content—whether it be firewall, VPNs, NAT, or authentication. The issue of availability alone can be solved by providing redundant devices. However, during failover to a redundant device, it is very difficult to preserve state for all of these different applications. The only way to preserve state and make the failover or load sharing completely transparent is to have the physical device act as ...