Huawei NetEngine80E Configuration Manual - Reliability page 177

HUAWEI NetEngine80E/40E Router
Configuration Guide - Reliability
Context
The following time parameters can be set to optimize the functions of a VRRP IPv6 backup
group:
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Procedure
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Issue 02 (2014-09-30)
Preemption delay: A master/backup VRRP switchover is frequently performed on an
unstable network where the BFD or EFM status tracked by a VRRP IPv6 backup group is
flapping or backup routers are unable to receive VRRP IPv6 Advertisement packets within
a specified period. This causes network flapping. To prevent this problem, set a preemption
delay. routers in a VRRP IPv6 backup group will preempt the Master state after the specified
delay.
Interval at which the master router sends ND packets: The master router broadcasts an ND
packet to update the ND entries on user devices before these entries age. The interval at
which the master router sends an ND packet must be shorter than the aging time of the ND
entry on each user device.
Interval at which VRRP IPv6 Advertisement packets are sent: The master router
periodically broadcast a VRRP IPv6 Advertisement packet to backup routers to notify them
of its normal status. If backup routers do not receive any VRRP IPv6 Advertisement packets
after the interval at which VRRP IPv6 Advertisement packets are sent expires, the backup
router with the highest priority becomes the new master.
Set the preemption delay for a VRRP IPv6 backup group.
1. Run:
system-view
The system view is displayed.
2. Run:
interface interface-type interface-number
The interface view is displayed.
3. Run:
vrrp6 vrid virtual-router-id preempt-mode timer delay delay-value
The preemption delay is set for routers in a VRRP IPv6 backup group.
By default, the preemption mode is enabled and the preemption delay is 0 seconds,
meaning immediate preemption. In a VRRP IPv6 backup group working in immediate
preemption mode, a backup router can immediately preempt the Master state when
its priority is higher than the master router. After preemption is complete, the master
router becomes a backup router. After the preemption delay is set, a backup router
preempts the Master state after a specified delay.
The vrrp6 vrid preempt-mode disable command is used to set the non-preemption
mode for routers in the VRRP backup group. In a VRRP IPv6 backup group working
in non-preemption mode, the master router that is working properly can retain the
Master state. This state cannot be preempted even if the master router's priority
decreases.
To restore the default preemption mode, run the undo vrrp6 vrid preempt-mode
command.
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