The SITECONNECTIVITYDOWN alarm is a critical alert in Prisma SD-WAN that signifies a complete loss of overlay connectivity for a specific site. This alarm is triggered precisely when all Secure Fabric Links (the VPN tunnels that form the SD-WAN overlay) from the site to all its remote peers (like data centers or other branches) have gone down. This means the site is effectively isolated from the rest of the SD-WAN fabric, even if its underlying internet circuits are still active.

A. A device power loss or reboot would generate a DEVICEUNREACHABLE or DEVICEREBOOTED alarm, which is distinct from a site-level connectivity failure.

B. The failure of a single internet circuit triggers a CIRCUITDOWN or PATHDOWN alarm. The site would remain connected through its other active circuits.

D. Exceeding licensed bandwidth triggers a licensing-specific alarm and does not indicate a loss of network connectivity.

1. Palo Alto Networks Prisma SD-WAN Administrator's Guide: In the section on monitoring alarms, the SITECONNECTIVITYDOWN alarm is explicitly defined.

Source: Palo Alto Networks TechDocs, "Monitor Alarms".

Reference: The table listing "System-Generated Alarms" specifies the trigger for SITECONNECTIVITYDOWN as "All Secure Fabric links from the site are down." This confirms that the loss of all VPNs, not just one circuit or a device reboot, is the specific condition.