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Zorluk: OrtaFirst Hop Redundancy Protocols (HSRP and VRRP)

Place the operational events in chronological order from first to last during an HSRP interface tracking failover scenario, assuming preemption is enabled on the standby router.

  1. 1The monitored uplink interface on the Active router experiences a link failure, triggering the configured interface tracking process.
  2. 2The Active router automatically decrements its HSRP priority by the specified tracking value.
  3. 3The Active router broadcasts an HSRP Hello packet reflecting its newly reduced priority value across the subnet.
  4. 4The Standby router compares the received priority, detects that its own priority is higher, and transmits a Coup message to initiate takeover.
  5. 5The newly promoted Active router transmits a Gratuitous ARP (GARP) message to update Layer 2 switch ports with the location of the Virtual MAC.

Cevap

The correct chronological order for HSRP interface tracking failover is: (1) The monitored uplink interface on the Active router fails; (2) The Active router decrements its HSRP priority; (3) The Active router broadcasts an HSRP Hello packet with the reduced priority; (4) The Standby router detects its higher priority and sends a Coup message; (5) The newly promoted Active router broadcasts a Gratuitous ARP to update Layer 2 MAC address tables.
HSRP interface tracking failover follows a precise operational order: First, the tracked uplink interface fails on the Active router. Second, the Active router decrements its configured HSRP priority locally. Third, it advertises this reduced priority in an HSRP Hello packet. Fourth, the Standby router (with preemption enabled) receives the Hello, recognizes its priority advantage, and sends a Coup message to claim the Active role. Finally, the newly active router sends a Gratuitous ARP (GARP) to refresh Layer 2 switch forwarding tables for the virtual MAC address.

Adım Adım Çözüm

1
Identify the initial trigger for tracking failover.
The monitored uplink interface fails, activating the tracking object on the Active router.
Interface tracking relies on physical or logical link state changes to initiate priority modification.
2
Determine the immediate local router response to the trigger.
The Active router reduces its operational priority by the configured decrement value.
HSRP tracking dynamically adjusts priority values to allow healthier backup routers to take over.
3
Determine how the priority change is communicated to the network.
The Active router advertises the lowered priority in its next HSRP Hello packet.
Peers must receive an updated Hello packet to learn about priority changes on neighboring devices.
4
Analyze the reaction of the Standby router.
The Standby router notices its priority is superior and sends a Coup message to assume the Active role.
Preemption permits a router with higher priority to claim the Active role immediately upon detecting lower priority Hellos.
5
Identify how Layer 2 network topology adjusts to the new Active router.
The newly active router broadcasts a Gratuitous ARP to force switches to update their MAC tables for the Virtual MAC.
Layer 2 switch ports must point to the new physical port holding the Virtual MAC to prevent traffic blackholing.

Anahtar Kavram

HSRP Interface Tracking and Preemption Failover
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Konular

First Hop Redundancy Protocols (HSRP and VRRP)

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