Alcatel-Lucent 7750 SR OS - Manual (Page 187)

VRRP
7750 SR OS Router Configuration Guide Page 187
Host Unreachable Priority Event
The host unreachable priority event creates a continuous ping task that is used to test connectivity
to a remote host. The path to the remote host and the remote host itself must be capable and
configured to accept ICMP echo request and replies for the ping to be successful.
The ping task is controlled by interval and size parameters that define how often the ICMP request
messages are transmitted and the size of each message. A historical missing reply parameter
defines when the ping destination is considered unreachable.
When the host is unreachable, the host unreachable priority event is considered true or set. When
the host is reachable, the host unreachable priority event is considered false or cleared.
Route Unknown Priority Event
The route unknown priority event defines a task that monitors the existence of a given route prefix
in the system’s routing table.
The route monitoring task can be constrained by a condition that allows a prefix that is less
specific than the defined prefix to be considered as a match. The source protocol can be defined to
indicate the protocol the installed route must be populated from. To further define match criteria
when multiple instances of the route prefix exist, an optional next hop parameter can be defined.
When a route prefix exists within the active route table that matches the defined match criteria, the
route unknown priority event is considered false or cleared. When a route prefix does not exist
within the active route table matching the defined criteria, the route unknown priority event is
considered true or set.