Alcatel-Lucent 7705 - VRRP Priority Control Policy In-Use Priority; VRRP Priority Control Policy Priority Events

VRRP Priority Control Policies
222 7705 SAR OS Router Configuration Guide
Non-owner virtual router instances must have a base priority value between 1 and 254. The
value 0 is reserved for master termination. The value 255 is reserved for owners. The default
base priority for non-owner virtual router instances is 100.
VRRP Priority Control Policy In-use Priority
A VRRP priority control policy enforces an overall minimum value that the policy can inflict
on the VRRP virtual router instance base priority. This value provides a lower limit to the
delta priority event manipulation of the base priority.
A delta priority event is a conditional event defined in the priority control policy that subtracts
a given amount from the current, base priority for all VRRP virtual router instances to which
the policy is applied. Multiple delta priority events can apply simultaneously, creating a
dynamic priority value. The base priority for the instance, less the sum of the delta values,
derives the actual priority in-use value.
An explicit priority event is a conditional event defined in the priority control policy that
explicitly defines the in-use priority for the virtual router instance. The explicitly defined
values are not affected by the delta in-use priority limit. If multiple explicit priority events
happen simultaneously, the lowest value is used for the in-use priority. The configured base
priority is not a factor in explicit priority overrides of the in-use priority.
The allowed range of the delta in-use priority limit is 1 to 254. The default is 1, which
prevents the delta priority events from operationally disabling the virtual router instance.
VRRP Priority Control Policy Priority Events
This section contains information on the following topics:
• Priority Event Hold-set Timers
• Port Down Priority Event
• Host Unreachable Priority Event
• Route Unknown Priority Event
The main function of a VRRP priority control policy is to define conditions or events that
impact the ability of the system to communicate with outside hosts or portions of the network.
If one or more of these events are true, the base priority on the virtual router instance is either
overwritten with an explicit value, or a sum of delta priorities is subtracted from the base
priority. The result is the in-use priority for the virtual router instance. Any priority event can
be configured as an explicit event or a delta event.