Alcatel-Lucent 7750 SR-OS, Руководство по настройке

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Page 360 7750 SR OS Router Configuration Guide
preempt
Syntax [ no ] preempt
Context config>router>if>vrrp
config>router>if>ipv6>vrrp
Description This command enables the overriding of an existing VRRP master if the virtual router’s in-use
priority is higher than the current master.
The priority of the non-owner virtual router instance, the preempt mode allows the best available
virtual router to force itself as the master over other available virtual routers.
When preempt is enabled, the virtual router instance overrides any non-owner master with an in-use
message priority value less than the virtual router instance in-use priority value. If preempt is
disabled, the virtual router only becomes master if the master down timer expires before a VRRP
advertisement message is received from another virtual router.
Enabling preempt mode improves the effectiveness of the base priority and the VRRP priority
control policy mechanisms on the virtual router instance. If the virtual router cannot preempt an
existing non-owner master, the affect of the dynamic changing of the in-use priority is diminished.
The preempt command is only available in the non-owner vrrp nodal context. The owner may not
be preempted because the priority of non-owners can never be higher than the owner. The owner
always preempts all other virtual routers when it is available.
Non-owner virtual router instances only preempt when preempt is set and the current master has an
in-use message priority value less than the virtual router instances in-use priority.
A master non-owner virtual router only allows itself to be preempted when the incoming VRRP
advertisement message priority field value is one of the following:
• Greater than the virtual router in-use priority value.
• Equal to the in-use priority value and the source IP address (primary IP address) is greater than
the virtual router instance primary IP address.
By default, preempt mode is enabled on the virtual router instance.
The no form of the command disables preempt mode and prevents the non-owner virtual router
instance from preempting another, less desirable virtual router.
Default preempt — The preempt mode enabled on the virtual router instance where it will preempt a VRRP
master with a lower priority.
priority
Syntax priority base-priority
no priority
Context config>router>if>vrrp
config>router>if>ipv6>vrrp
Description This command configures the base router priority for the virtual router instance used in the master
election process.