HSRP vs VRRP: What's the Difference?

What they are: first-hop redundancy

Both HSRP and VRRP are First Hop Redundancy Protocols (FHRPs). Hosts point their default gateway at a single virtual IP that is shared by a group of routers, plus a matching virtual MAC. The routers elect one to forward traffic for that virtual IP; if it goes down, another router takes over the same virtual IP and MAC, so hosts never have to change their gateway setting and failover is transparent.

HSRP is Cisco's original version of this idea: an Active router forwards and a Standby router monitors it, ready to step in. VRRP is the open-standard equivalent defined in RFC 5798, so it works between Cisco and non-Cisco routers; its forwarding router is the Master and the others are Backups.

GLBP (Gateway Load Balancing Protocol) is a separate Cisco-proprietary FHRP worth knowing by name. Unlike HSRP and VRRP, where only one router forwards at a time, GLBP load-balances traffic across multiple gateways simultaneously, so several routers actively share the outbound load rather than sitting idle on standby.

The differences that matter

Vendor and interoperability: HSRP is Cisco-only, so every router in the group must be Cisco. VRRP is an open standard, so it can run across gear from different vendors — that interoperability is its main reason to exist.

Terminology: HSRP uses Active/Standby; VRRP uses Master/Backup. Same concept, different words, and exam questions lean on this distinction.

Preempt default: This is the classic trap. HSRP has preempt OFF by default, so a router that fails and recovers stays Standby even if it has the higher priority. VRRP has preempt ON by default, so a recovered higher-priority router automatically takes back the Master role.

Under the hood: the virtual MAC ranges differ (HSRP 0000.0C07.ACxx, VRRP 0000.5E00.01xx, where the last byte is the group/VRID), and so does transport — HSRP rides on UDP port 1985 while VRRP runs directly over IP as protocol number 112.

When to choose each

Choose HSRP when the environment is all Cisco. It is mature, widely deployed, and its behavior is well understood by Cisco-trained teams. The predictable, non-preempting default can also be desirable in change-controlled networks where you do not want a recovered router to flip roles on its own.

Choose VRRP when you have (or might add) non-Cisco routers, or when a standards-based design is a requirement. Because it is an open standard, it avoids vendor lock-in for the gateway redundancy layer.

For raw redundancy the two are functionally equivalent — a shared virtual gateway with fast failover — so the deciding factors are usually vendor mix and organizational standardization, not performance. If the goal is to actively use both routers' bandwidth at once rather than keep one idle, that is GLBP's niche, not HSRP's or VRRP's.

A common gotcha

The preempt default catches people who move between the two. With HSRP, after you fix the primary router it will NOT automatically resume the Active role unless you explicitly enable preempt — so traffic may keep flowing through the lower-priority router indefinitely, which surprises engineers expecting the 'better' router to take back over. With VRRP the opposite happens: preempt is on by default, so the higher-priority router reclaims Master the moment it comes back, which can cause an unexpected failback (and a brief blip) right after a maintenance window.

One more VRRP-specific concept: if the virtual IP is the same as a router's real interface IP, that router is the 'address owner' and runs at priority 255, so it always wins the election. HSRP has no equivalent address-owner concept. When comparing the two, don't assume identical failover behavior just because the virtual IP looks the same on both sides.