Copyright (c) 2026 MindMesh Academy. All rights reserved. This content is proprietary and may not be reproduced or distributed without permission.

4.5.2. How FHRPs Work

Loading diagram...
The handoff process:
  1. Active router sends hellos every 3 seconds (HSRP default)
  2. Standby router listens. If it misses 3 hellos (hold time = 10 sec), it assumes active is dead
  3. Standby becomes active, takes ownership of the VIP and virtual MAC
  4. Standby sends gratuitous ARP to update switch MAC tables
  5. Traffic now flows through the new active router
Key Concepts:
  • Virtual IP (VIP): The gateway IP clients configure—shared between routers, never changes
  • Virtual MAC: A special MAC that moves with the VIP (so switches forward to the right router)
  • Active/Master: Currently answering for the VIP and forwarding traffic
  • Standby/Backup: Monitoring, ready to take over
  • Preemption: If enabled, a higher-priority router can reclaim active role after recovering
Common configuration:
Router(config)# interface GigabitEthernet0/0
Router(config-if)# standby 1 ip 192.168.1.1          ! Virtual IP
Router(config-if)# standby 1 priority 110            ! Higher = more likely active
Router(config-if)# standby 1 preempt                 ! Take over if I have higher priority

⚠️ Exam Trap: HSRP and VRRP provide redundancy but not load balancing—all traffic goes through the active router while the standby sits idle. If you want both routers forwarding traffic, either use GLBP or create two HSRP groups (one where R1 is active for VLAN 10, another where R2 is active for VLAN 20).