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NOTE
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As CFM can only detect failure in local links, not remote links, the backup NPE2 is also unable to
detect remote link failures. NPE2 resorts to VRRP packet negotiation before becoming the Master
to direct traffic. This mode causes extended service interruption time. To minimize service down
time, associate VRRP with peer BFD, accelerating VRRP switching.
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When CFM between UPE2 and NPE1 detects a link failure, a notification is sent to the VRRP
backup group on NPE1, and the sessions of both the peer BFD and the local CFM to go Down.
Consequently, the VRRP status of the master NPE1 changes to Initialize.
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When the peer BFD session is Down, and the local CFM session is Up, the VRRP status of the
backup NPE2 changes to Master.
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In the preceding scenario, CFM can be associated with VRRP, and VRRP associated with peer BFD
to implement a rapid master/backup VRRP switchover when CFM detects a link failure. User traffic
can then be forwarded quickly by the backup NPE to minimize service interruption time. PE1 cannot
detect the master/backup VRRP switchover so still sends network traffic to NPE1, which wastes
bandwidth resources and interrupts services. To prevent this, VRRP can be associated with the direct
network segment route. Preference of the direct route is reduced during master/backup VRRP
switchover, ensuring that the uplink traffic from users and the downlink traffic from the NPE travel
through the same path.
VRRP can be associated with CFM, peer BFD, and direct routes to implement VRRP
switchovers quickly, and to ensure consistent uplink and downlink traffic paths should a link
failure occur.
HUAWEI NetEngine80E/40E Router
Configuration Guide - Reliability
8 Ethernet OAM Configuration
Issue 02 (2014-09-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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