High Availability mode allows two Vigor3900 routers to be interconnected to provide a standby router (Slave) which will come online once the master unit fails providing full time availability.

The high availability of the V3900 Series is designed to avoid single points-of-failure. When failures occur, the failover process moves processing performed by the failed component (the “Master”) to the backup component (the “Slave”). This process remains system-wide resources, recovers partial of failed transactions, and restores the system to normal within a matter of microseconds.

We will use the example below to show how to configure two Vigor3900 routers for High Availability mode.

Here we have a common ADSL connection which is fed to both router WAN ports. The Slave will place its WAN interface in standby mode and will only bring up the WAN connection if the Master Vigor3900 router fails. Communication between the Master and Slave occur via the LAN connection to the Network switch. Changes made to the Master unit will be copied to the slave unit automatically.  However firmware upgrades to the Master and the Slave units must be carried out individually.

In our example we will use the following settings:

Master Vigor3900 Slave Vigor3900
IP Address: IP Address:
Subnet Mask Subnet Mask
Virtual IP Virtual IP
Peer IP Peer IP
LAN Default Gateway LAN Default Gateway


Go to Applications>>High Availability configuration menu and enter the settings as shown below:

Master Vigor3900

Slave Vigor3900

Once the routers are configured connect the LAN port of each router to a common VLAN on the network switch.

The WAN connection will also need to be attached to both routers on identical WAN ports.  Each router will need to have identical configuration settings except for the router IP addresses and High Availability settings as shown above.

You will need to have the Default Gateway settings for the PC’s set to the Virtual IP address so it will not matter which router is active and on-line.


To test, switch off the master router and you should notice that the Slave router will become active and start up the WAN connection. You should still be able to access the Internet.  Switching on the Master router should cause the network connections to be transferred to the Master once the Master becomes active.