Association Between VRRP and Link Status
In some situations, additional technologies are required to enhance the VRRP redundancy function. For example, if the link from the master to a network is disconnected, VRRP cannot detect the fault or switch services. In addition, hosts cannot remotely access the network through the master. To solve this problem, configure VRRP to monitor the specified interface or uplink status.
Once configured, when the master detects that the interface or uplink fails, the master reduces its priority to be lower than that of the backup and immediately sends VRRP Advertisement packets. After the backup receives the VRRP Advertisement packets, it detects that the priority in the VRRP Advertisement packets is lower than its priority. The backup switches to the master, ensuring traffic forwarding is not interrupted.
VRRP Monitoring the Status of the Interface Connected to the Uplink
When the interface connected to the uplink goes Down, the master reduces its priority so that the backup switches to the master to forward traffic.
As shown in Figure 1, a VRRP group is configured between SwitchA and SwitchB, which are the master and backup, respectively. Both switches work in preemption mode. Association between VRRP and uplink interface Interface1 is configured on SwitchA. When Interface1 fails, the priority of SwitchA decreases. Then SwitchB becomes the master through negotiation, ensuring that user traffic is forwarded correctly.
Associating VRRP with BFD/NQA/Routing to Monitor the Remote Host or Network Connected to the Uplink
BFD/NQA/Routing detects connectivity of the uplink on the master. When the uplink of the master fails, BFD/NQA/routing detects the fault and instructs the master to adjust its priority. This triggers an active/standby switchover and ensures proper traffic forwarding.
As shown in Figure 2, a VRRP group is configured between SwitchA and SwitchB, which are the master and backup, respectively. Both switches work in preemption mode. BFD/NQA/Routing is configured to monitor the link from SwitchA to SwitchE, and association between VRRP and BFD/NQA/routing is configured on SwitchA. When BFD/NQA/routing detects the fault on the link from SwitchA to SwitchE, BFD/NQA/routing instructs the master to adjust its priority. Through VRRP Advertisement packet negotiation, SwitchB switches to the master so that user traffic is forwarded correctly.