Unicast VRRP
Background
Common VRRP is multicast VRRP and only allows VRRP Advertisement packets to be multicast. Multicast VRRP Advertisement packets, however, can be forwarded within only one broadcast domain (for example, one VLAN or VSI). Therefore, common VRRP backup groups apply only to Layer 2 networks. This limitation means that common VRRP does not apply to devices on a Layer 3 network that need to negotiate their master/backup status using VRRP.
To address this issue, Huawei develops unicast VRRP based on VRRPv2, which allows VRRP Advertisement packets to pass through a Layer 3 network. After a unicast VRRP backup group is configured on two devices on a Layer 3 network, the master device in this group sends unicast VRRP Advertisement packets to the backup device through the Layer 3 network, implementing the master/backup status negotiation between the two devices.
Implementation
The implementation of unicast VRRP is similar to that of common VRRP..
- Security authentication: MD5 or HMAC-SHA256 authentication can be configured for a unicast VRRP backup group to improve network security.
- Delayed preemption: This function prevents the master/backup status of devices in a unicast VRRP backup group from changing frequently, thereby ensuring network stability.
- Association with a VRRP-disabled interface, and BFD: If the master device in a unicast VRRP backup group fails, the backup device immediately takes over, thereby ensuring network reliability.
- Association with an interface monitoring group: When the link
failure ratio on the access or network side reaches a specified threshold,
the unicast VRRP backup group performs a master/backup switchover
to ensure network reliability.
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NOTE: As an extension to association between a unicast VRRP backup group and a VRRP-disabled interface, association between a unicast VRRP backup group and an interface monitoring group reduces the configuration workload and implements uplink and downlink monitoring.
Usage Scenario
Unicast VRRP applies when two devices on a Layer 3 network need to use VRRP to negotiate their master/backup status.
Benefits
Unicast VRRP allows two devices on a Layer 3 network to use VRRP to negotiate their master/backup status. Unicast VRRP can be associated with a VRRP-disabled interface, BFD, If the master device in a unicast VRRP backup group fails, the backup device rapidly detects the fault and becomes the new master device.
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