During a scheduled high-availability failover test, a network administrator powers down Core Router A, which participates in a Virtual Router Redundancy Protocol (VRRP) group with Core Router B. Core Router A has a physical IP address of 10.1.10.2, Core Router B has a physical IP address of 10.1.10.3, and the VRRP virtual IP (VIP) is 10.1.10.1. Immediately following the shutdown, several workstations lose connection to remote networks. Troubleshooting reveals that these workstations have their default gateway statically configured as 10.1.10.2. What is the root cause of the connectivity failure?
- The workstations were configured with the primary router's physical interface IP address rather than the VRRP virtual IP address.Answer
- BCore Router B was blocked from forwarding traffic because its Spanning Tree Protocol (STP) priority was set to a higher numerical value than Core Router A.
- CThe affected workstations were assigned IP addresses that reside on a different IP subnet than the default gateway IP address.
- DVRRP preempt mode was active on Core Router B, forcing it to reject virtual router master status until Core Router A rebooted.
Answer
The workstations were configured with the primary router's physical interface IP address rather than the VRRP virtual IP address.
For First Hop Redundancy Protocols (FHRP) such as VRRP or HSRP to function properly, host devices must use the Virtual IP (VIP) as their default gateway. When hosts are configured with the physical interface IP of a specific router, high-availability mechanism is bypassed. Powering down that physical router breaks outbound routing for those hosts because the standby router only intercepts traffic addressed to the VIP.
Step-by-Step Solution
Key Concept
FHRP Virtual Gateway IP Configuration
Estimated Time:1m 30s