First Hop Redundancy Protocol

  1. What is HSRP?
    Hot Standby Router Protocol - Created by Cisco.
  2. What are the default timers for HSRP?
    Hello packets sent every 3 seconds; Hold Timers every 10 seconds
  3. What is VRRP?
    Virtual Router Redundancy Protocol - Created by IETF
  4. What are the default timers for VRRP?
    Hello packets every 1 second, hold timers every 3 seconds.
  5. What are the primary differences between HSRP and VRRP?
    The timers are shorter for VRRP. VRRP can re-use one of the interface's IP addresses as the virtual IP address.
  6. What is GLBP?
    Gateway Load Balancing Protocol - Cisco proprietary
  7. What is the primary difference between HSRP and GLBP?
    GLBP allows for Active-Active load balancing, while HSRP only allows one node to be active.
  8. How are routers grouped in HSRP?
    Routers are grouped into standby groups. One router is active, and the others are in standby.
  9. How are routers arranged in GLBP?
    One router is the Active Virtual Gateway, which responds to ARP requests. Remaining gateways act as Active Virtual Forwarders.
  10. What are the steps to enable HSRP?
    • 1. Create standby group
    • 2. Reassign IP address
    • 3. Verify
    • 4. Optimize and tune
  11. What is the command to enable an HSRP standby group?
    standby [Group ID] ip [Shared IP address]
  12. How does HSRP determine which is the active router?
    The router with the highest priority becomes active. Tie goes to the router with the highest IP address.
  13. How do you see the HSRP configuration?
    show standby
  14. How is the priority set for HSRP?
    standby [Group ID] priority [value]
  15. What is HSRP pre-emption?
    Preemption forces a router to take over if its priority is higher - this take effect when a router that was down comes back up. Preemption is not enabled by default.
  16. How do you prevent faulty hardware from breaking HSRP groups?
    You can set the minimum uptime required by before a preemptive router takes over: standby [Group ID] preempt delay minimum [minutes]
  17. How do you set the hold timers?
    standby [Group ID] timers [hello timer] [hold timer]
  18. How do you set up authentication in HSRP?
    standby [Group ID] authentication md5 [key-chain|key-string] [word]
  19. How can HSRP detect if a next-step interface went down?
    standby [Group ID] track [interface] [decrement value] -if the interface goes down then the priority goes down by the specified value
  20. What are the steps required to enable VRRP?
    • 1. Create VRRP group
    • 2. Verify
    • 3. Optimize and tune
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First Hop Redundancy Protocol