HSRP vs VRRP vs GLBP: What Cisco Exams Expect

First Hop Redundancy in One Picture

First Hop Redundancy Protocols (FHRPs) such as HSRP, VRRP and GLBP protect user subnets from default gateway failures. Instead of pointing PCs directly at a physical router, you give them a virtual IP address that is backed by one or more devices.

Cisco exams expect you to know where these protocols are similar, where they differ and how to configure common scenarios quickly and correctly.

What They Have in Common

All three protocols:

• Provide a virtual default gateway IP for end hosts.
• Use a virtual MAC address to receive traffic from clients.
• Elect one device to forward most or all traffic in normal operation.
• Support failover to another device if the active gateway fails.

In many exam questions, this shared behavior is more important than the minor differences.

Key Differences: HSRP vs VRRP vs GLBP

At a high level:

• HSRP is Cisco-proprietary and commonly used in Cisco-only networks.
• VRRP is an open standard, often chosen in multi-vendor designs.
• GLBP goes further by load-balancing across multiple active gateways.

VRRP allows the master router to use its own IP as the virtual IP, while HSRP typically uses a dedicated virtual address. GLBP’s special feature is that it can hand out different virtual MAC addresses to different clients, distributing the load while preserving a single gateway IP.

Common Exam Scenarios and Pitfalls

Cisco exams like to test:

• Configuring priorities and preemption safely.
• Tracking interfaces so that a failure can trigger gateway failover.
• Interpreting show command output to see which device is active/master.

A classic pitfall is enabling preemption without careful design, which can cause gateways to flip roles repeatedly. Another is forgetting to configure the same virtual IP on both devices, leading to clients sending traffic into a black hole.

Design Tips for Real Networks

In production, simplicity and predictability are more important than clever tricks:

• Keep the number of FHRP groups manageable.
• Document which device should be active for which VLAN.
• Align FHRP roles with routing protocol roles to avoid asymmetric paths.

When combined with good monitoring, FHRPs give you robust gateway redundancy with minimal impact on end hosts—they keep using the same default gateway IP, even when devices fail behind the scenes.

Article Details

• Level: CCNA / CCNP
• Topic: First Hop Redundancy
• Audience: Enterprise network engineers

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