Chapter 39 Device HA
ZyWALL USG 300 User’s Guide
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Legacy Mode ZyWALL VRRP Application
In VRRP, a virtual router represents a number of ZyWALLs associated with one IP
address, the IP address of the default gateway. Each virtual router is identified by
a unique 8-bit identification number called a Virtual Router ID (VR ID). In the
example below, ZyWALL A and ZyWALL B are part of virtual router 10 with IP
address 192.168.10.254.
Figure 484 Example: VRRP, Normal Operation
The VR ID is not shown. In normal operation, ZyWALL A is the master. It has the
same IP address as the default gateway and forwards traffic for the network.
ZyWALL B is a backup. It is using its management IP address 192.168.10.112.
ZyWALL A sends regular messages to ZyWALL B to let ZyWALL B know that
ZyWALL A is available. If ZyWALL A becomes unavailable, it stops sending
messages to ZyWALL B. ZyWALL B detects this and assumes the role of the
master. This is illustrated below.
Figure 485 Example: VRRP, Master Becomes Unavailable
ZyWALL B is now using the IP address of the default gateway, and it is forwarding
packets for the network. The loss of ZyWALL A has no effect on the network.
If there is more than one backup ZyWALL, the backup ZyWALL with the highest
priority becomes the master. The other backup ZyWALLs remain backups.
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