ZyXEL Communications ZyWALL 1000 manual 494

Chapter 33 Device HA

"Every router in a virtual router must use the same advertisement interval.

If Router A becomes unavailable, it stops sending messages to Router B. Router B detects this and assumes the role of the master router. This is illustrated below.

Figure 364 Example: VRRP, Master Becomes Unavailable

Router B is now using the IP address of the default gateway, and it is forwarding packets for the network. The loss of Router A has no effect on the network.

If there is more than one backup router, the backup router with the highest priority becomes the master router. The other backup routers remain backup routers.

If Router A becomes available again, one of two things can happen, depending on the settings in Router A.

1Router A may preempt Router B and become the master router again. In this case, the network returns to the state shown in Figure 363 on page 493.

2Router A returns to the network, but Router B remains the master router. This is illustrated below.

Figure 365 Example: VRRP, No Preempt

In this case, Router A becomes a backup router, and it uses its Manage IP, 192.168.10.111. Router B remains the master router until it becomes unavailable.

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	ZyWALL USG 1000 User’s Guide