This is how often, in seconds, 0 to 30, this device sends RSVP-TE Hello messages on this interface to maintain and monitor the signaling adjacency with its neighbor. This value must be coordinated with the Hello tolerance and with whatever interval the neighbor uses; a device sending Hellos far less frequently than its neighbor expects, combined with a tight tolerance, can cause the neighbor to declare the adjacency down even though this device considers the link fine. For example, with this set to 3 seconds and a tolerance of 3, this device's neighbor should expect to detect a lost adjacency within roughly 9 seconds of an actual failure on this link.