Reports whether this tunnel link is designated as the primary path, a backup, or an on-demand, established-only-when-needed, path to the peer. This distinction matters operationally because a backup or on-demand tunnel being active instead of primary indicates a failover has already occurred; an admin monitoring this field can catch a silent failover to a backup link before users even notice degraded performance on the secondary path. Example: tunnelLinkPriority reporting backup(1) as currently carrying traffic, when it's normally on-demand(2) and idle, confirms the primary link to that site has failed over silently.