What is VRRP?

Virtual Router Redundancy Protocol (VRRP) is a standards-based protocol that removes the LAN default gateway as a single point of failure. Two or more routers share a virtual IP address; the router with the highest priority becomes active and forwards traffic, while the others stand by to take over instantly if it fails.

Key takeaways

• VRRP shares one virtual IP address among two or more LAN routers.
• The highest-priority router is active; the rest wait as backups.
• Preempt mode lets a recovered router reclaim the active role.
• Tracking objects cut priority when interfaces, routes, or monitors fail.
• Versa VOS runs VRRPv2 and VRRPv3, tunable against interchassis HA state.

On this page: Why it matters · How it works · Types · VRRP & Versa · FAQ

Why is VRRP important?

Every host on a LAN is configured with a single default gateway address, and that address is normally the one weak point in an otherwise redundant network: if the gateway router goes down, every host behind it loses its path out – regardless of how much redundancy exists further upstream. VRRP closes that gap without requiring end hosts to run a routing protocol or detect failures themselves. Hosts keep pointing at one unchanging address; VRRP handles which physical router answers to it.

Because VRRP is an open IETF standard rather than a vendor-proprietary mechanism, routers, firewalls, and SD-WAN appliances from different vendors can interoperate cleanly in the same redundancy group. That makes it the default choice for gateway high availability in branch offices, data centers, and campus networks.

What is VRRP?

VRRP groups two or more routers around one virtual IP address and, depending on configuration, one virtual MAC address. Each router in the group is assigned a priority (1–254, default 100); the router with the highest priority is elected active (also called master) and answers ARP requests and forwards traffic for the virtual address, while the rest sit in backup state, listening for periodic advertisements from the active router.

If the active router stops advertising – because it failed, its uplink dropped, or an administrator took it offline – the backup with the next-highest priority takes over the virtual address and begins forwarding, typically within a few seconds. Hosts never see the change: their gateway address never moves, only which physical router answers to it.

Types of VRRP

Two protocol versions are in use. VRRPv2 supports IPv4 only and is widely deployed. VRRPv3 adds IPv6 support and shortens the advertisement interval to a millisecond-granularity Fast Interval, enabling faster failover detection.

Election behavior is set by preempt mode: with preempt (the default), a higher-priority router that returns to service reclaims the active role immediately; with no-preempt, the router that took over stays active even after the original router recovers, avoiding unnecessary switchovers. A MAC address mode setting chooses whether the group advertises the active router’s physical MAC address or a shared virtual MAC for faster switchover. VRRP can also run in unicast peer mode instead of multicast, and priority tracking – of interfaces, routes, or IP SLA monitor objects – lets a router lower its own priority automatically when something it depends on degrades, so a backup with better connectivity can take over.

VRRP & Versa

Versa Operating System (VOS) devices configure VRRP as global VRRP options – MAC address mode, protocol version, and checksum behavior – plus per-interface VRRP groups with priority, preempt mode, virtual address, and advertisement thresholds. VRRP groups can also be configured directly while setting up an Ethernet interface or subinterface, for both IPv4 and IPv6. VOS supports tracking objects – interfaces, routes, and monitors – that subtract a configured priority cost from a group’s priority when the tracked object fails, and VRRP can provide HA for Azure VM pairs through Azure managed identity and UDR switching.

VRRP also interacts with stateful interchassis HA: the two failover mechanisms are independent, but Versa recommends keeping the VRRP-active role aligned with the HA-active device by configuring an HA Standby Priority Cost that lowers VRRP priority whenever a device’s HA state is standby, so the active HA node is always the one forwarding traffic for the virtual address.

Frequently asked questions

What is the difference between VRRP and HSRP?

VRRP is an open IETF standard (RFC 9568 for version 3; RFC 3768 for the older version 2) that any vendor can implement, while HSRP is a similar but Cisco-proprietary protocol. Both elect an active router to answer a shared virtual gateway address; VRRP is the right choice whenever devices from more than one vendor must interoperate.

What is the difference between VRRP version 2 and version 3?

VRRPv2 supports only IPv4 and remains widely deployed for legacy compatibility. VRRPv3 adds IPv6 support and introduces a millisecond-scale Fast Interval for advertisements, letting failover be detected and completed faster than VRRPv2’s second-granularity timers permit. Versa VOS treats VRRPv3 as the default version for new configurations.

What is VRRP preempt mode?

Preempt mode controls whether a recovered higher-priority router reclaims the active role. With preempt (the default), it takes back over immediately. With no-preempt, the current active router – even at lower priority – keeps forwarding, which avoids an extra switchover right after recovery.

How does VRRP priority tracking work?

A VRRP group can track interfaces, routes, or IP SLA monitors. Each tracked object has a priority cost; if it goes down, that cost is subtracted from the group’s configured priority. If the resulting priority drops below a peer’s, that peer takes over as active.

Can VRRP run alongside interchassis HA?

Yes. VRRP active/backup state and interchassis HA active/standby state are independent by default, so Versa recommends setting an HA Standby Priority Cost that lowers VRRP priority on the standby HA node – keeping the VRRP-active role tied to the active HA device.

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