What is High Availability?

Support Model : Vigor2860 SeriesVigor2860L/LnVigor2925 SeriesVigor2925L/LnVigor2952 SeriesVigor3220 Series
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High Availability provides hardware redundancy to the LAN clients. A High Availability group consists of 1 primary router and 1 (or several) secondary router for redundancy. There can be up to 10 routers in a group, i.e., 1 primary and 9 secondary. Following are the key features:

  • WCF License share (Hot-Standby only)

    Network administrators can create a High Availability group on MyVigor website and include at most 8 routers to join the group and share the same WCF license. Only 1 router (the primary) can use the license at a time, and when the primary router goes down, the secondary router will come up and register to MyVigor server and continuously provide firewall protections to your LAN clients. It means only one WCF license is required per High Availability group.

  • Configuration Sync (Hot-Standby only)
    Every configuration/modification made on the primary router will be synced to other group member(s), this ensures that once the secondary router become primary, your network will work like the same and the only way we notice the High Availability had happened is via the notification.

  • DDNS Update
    For dynamic WAN IP users, High Availability group members can share the same DDNS account, that when secondary router become primary, it will update the DDNS profile so the network can still be accessible via the same DDNS domain.


The only constrain of this feature is that all the member routers have to be exactly the same model, e.g., Vigor2925n working with Vigor2925n, Vigor2925n+ working with Vigor2925n+, and Vigor2925n can NOT work with Vigor2925n+ in this application.

Since 3.8.5 version firmware, Vigor Router can set up the High Availability network by the devices within the same series, which means the restriction has been loosened. With the new version firmware, Vigor2952n can work with Vigor2925n+, however, due to the hardware difference, when the backup model goes up, it may not provide the same service as the primary model, such as Vigor2925n can only provide 2.4GHz wireless LAN, but Vigor2925n+ can provide 2.4 and 5GHz. If the Vigor2925n+ goes down and Vigor2925n goes up, there will be only 2.4GHz wireless signal remain.

 

How High Availability works?

Each member router in the High Availability group has different LAN IP address, a "virtual IP" will be provided as gateway IP to the LAN clients and only the primary router responses to that virtual IP. Routers will negotiate out one primary router on the basis of the WAN status of each router and the priority ID set by network administrator. The negotiation will be triggered if the primary router down or there is the WAN status or configuration change on each router. If one of the secondary router is selected to become the primary router after negotiation, this new primary router will not only dial up the WAN but also update it's LAN MAC to the virtual IP to all the LAN clients (by broadcast), so LAN clients can continuously use the same gateway IP.

The following network topology shows that 2925_A and 2925_B have different LAN IP and MAC, and all the LAN clients are having 192.168.X.1 as virtual IP and the MAC is with 2925_A.

   

When a hardware redundancy incident happens, 2925_B dials up the WAN and updates it's MAC to LAN clients.

   

We may also confirm the MAC by typing the command "arp -a" in the command prompt:

V2925_A as primary

   

V2925_B as primary after a hardware redundancy incident

   

 

If the V2925_A back online, it will trigger the negotiation, V2925_A will become primary router again due to it has higher priority, V2925B will change status to secondary.

 

What are the differences between Hot-Standby and Active-Standby?

There are two redundancy methods available – Hot-Standby and Active-Standby, users may choose either mode for redundancy, and generally Hot-Standby is more often to see. Following is the comparison table and network topology:

 

WAN Source

Online Status

Configuration Sync

Hot-Standby

Primary and Secondary share the same WAN source. To share the same WAN source, a modem with several Ethernet ports or a hub/switch would be required.

Only Primary is online. When Primary goes down, Secondary comes up and use the same WAN line to dial up.

Configuration Sync from Primary to Secondary.

Active-Standby

Primary and Secondary have different WAN sources.

Both Primary and Secondary are online via their own different WAN lines.

No Configuration Sync.

Hot-Standby

Primary and Secondary router share the same WAN source. Usually, only the Primary is online. When Primary goes down, Secondary comes up and use the same WAN line to dial up, and continue to provide Internet service to LAN clients. If there is a LAN does not be set to have the hardware redundancy, it will not able to access the internet after the primary router goes down.

   

- LAN1 is the High Availability Management LAN.

- LAN2 and LAN3 are set to have the hardware redundancy, it will access the internet through V2925_A at normal; if the primary router goes down, these two LANs will access the internet through the V2925_B.

- LAN4 does not have the hardware redundancy, it will access the internet through V2925_A only; if the primary router goes down, this LAN will lost the internet connection.

 

Active-Standby

Active-Standby mode is almost same as Hot-Standby mode, only that in the Active-Standby mode, the Primary and Secondary connect to the different WAN sources; also, the Secondary will always be online. The clients of the LAN which is configured to have the hardware redundancy (LAN2 and LAN3 in the following topology) will access the internet through the primary router, when the primary router goes down, these clients will access the internet through the secondary router. The clients of the LAN which does not have the hardware redundancy setup (LAN4 and LAN5 in the following topology) will access the internet through the router which they connect to; when their router goes down, they will not be able to access the internet anymore.

   

- LAN1 is the High Availability Management LAN.

- LAN2 and LAN3 are set to have the hardware redundancy, these two LANs will access the internet through V2925_A at normal; if the primary router goes down, these two LANs will access the internet through the V2925_B.

- LAN4 and LAN5 do not have the hardware redundancy, they will access the internet through the router they connect to only; if the router they connect to goes down, these LANs will lost the internet connection.

 

See also:

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