Minimising network downtime is an important aspect of business continuity, particularly given that many organisations are now using one network for all voice and data communications. As a consequence, the Virtual Router Redundancy Protocol (VRRP) has become increasingly popular for safeguarding critical communications.
VRRP specifies a process in which multiple routers act in a coordinated manner on a local area network to appear as a single gateway. The group of VRRP routers will elect a single master that assumes responsibility for forwarding IP packets across the wide area network to ensure that communications are received successfully. The master will be determined by the configured VRRP priority in each router, with the highest value assuming the role. Should this master become unavailable, it will be detected by the other routers and the next highest configured VRRP priority will assume the role. Thus, the gateway represented by this group of VRRP routers remains up and running, with employees blissfully unaware that individual units in the group have failed.
Whilst the concept is simple and effective, basic VRRP has its limitations. Most notably, if the WAN side of the currently elected master becomes inoperable – and the master fails to detect the problem – the virtual router as a whole will fail, at which point everyone in the business will notice.
