Gratuitous ARP Troubleshooting for School Recognition Display Failover
A school recognition display, athletic hall-of-fame kiosk, or lobby honor wall depends on a continuous network path to its content platform. That path runs through a default gateway, and in schools using redundant network infrastructure — paired core switches with HSRP or VRRP, or a virtual server IP that migrates between hosts — the gateway’s or content server’s IP address may remain the same while the underlying MAC address changes. When that change happens, every device on the affected broadcast segment, including the recognition display, must update its ARP cache to learn the new MAC for the existing IP. The mechanism designed to make that update happen automatically is the gratuitous ARP (GARP): an unsolicited ARP packet that the newly active device broadcasts to announce its IP-to-MAC binding to all neighbors.
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