VRRP: The Wrong Router Is Master
Nothing is down and the gateway answers, yet traffic takes the backup path. Read the election the way VRRP ran it, live, right below.
Symptom
The virtual gateway answers and nothing is down, but the backup router carries all the traffic. Read the election the way VRRP ran it.
Your mission
Inspect, recover, then verify
Format
Cisco IOS CLI
Investigate before you configure.
Use the CLI evidence to isolate the fault, make the smallest safe correction, then verify the network state changed.
Observe the symptom and link state.
Diagnose by comparing the protocol evidence.
Verify the expected device state and confirm the original symptom is resolved.
Console access: R1 · R2
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Need a hint?
Reveal the root cause when you're ready.
Try the investigation first, then use this as your escape hatch, not a dead end.
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Lab debrief
Turn the session into a repeatable troubleshooting pattern.
Use this reference after your attempt: first explain the symptom, then verify the evidence, then confirm the repair.
The problem
R1 was specified as the primary gateway for VLAN 10 and R2 as the backup. Monitoring shows all of VLAN 10's traffic leaving through R2.
What you'll practice
- Read Pri, Pre, State and master address in show vrrp brief
- Explain the highest-IP tie-breaker when priorities are equal
- Know that VRRP preempts by default and HSRP does not
- Change the master deliberately with vrrp priority
The topology
R1 (192.168.10.2) and R2 (192.168.10.3) share Gi0/0 on VLAN 10 and run VRRP group 10 with virtual address 192.168.10.1.
Commands to run yourself
The real diagnostic commands for this lab, copy-paste ready. Run these in the same order to reproduce the investigation on your own session.
show vrrp briefshow vrrpshow logging | include VRRPTopology diagram
Fact-checked references
The commands and behaviour in this lab were checked against these primary references.
Frequently asked
Why did R2 win when nobody configured it to?
Both routers kept the default priority of 100. VRRP then prefers the router with the highest primary IP address, and R2's 192.168.10.3 is higher than R1's 192.168.10.2.
Do I need to enable preemption on R1?
No. VRRP preemption is on by default, which the Pre column shows as Y. HSRP is the protocol that needs standby preempt configured explicitly.
What is the virtual MAC address?
VRRP uses 0000.5e00.01xx, where xx is the group number in hexadecimal. Group 10 is 0a, so hosts ARP for 192.168.10.1 and learn 0000.5e00.010a whichever router is master.
Ready to run this lab yourself?
No setup, no image sourcing. Book a session or ask for a live demo.