Use Cases
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Multi-Gateway Setup
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If you have a setup where you have multiple internet connections from e.g. different ISPs, you can set up multiple Gateways 
for an Interface that switch automatically if one goes down.

To do so go to **Routing -> Gateways**. Here you can see an overview of all the Gateways that are already configured.

.. image:: img/Gateways-Overview.png
  :width: 100%
  :align: center
  :alt: Overview of available Gateways

If you do not have your Gateways setup already, click **Add** to configure a new one.
Enter your **Gateway IP** and enable **Default Gateway** if you want this one to be
your primary Gateway.

.. image:: img/Gateways-Config1.png
  :width: 100%
  :align: center
  :alt: Gateway configuration

In the Monitoring section disable **Always Up** otherwise your VT AIR assumes that this Gateway is always operational and 
doesn't switch if the Gateway goes down. The **Monitoring IP address** should be a website (like Google) that is basically 
guaranteed to be up all the time. This way the system is able to determine whether the route is acutally usable beyond 
your Gateway. You should use different IPs for each Gateway though.

The ranking of the Gateway is determined by its weight factor **LB Weight**. Lower numbers are higher in importance.

Should you run a High Availability setup and you wish to have different Gateways between the Master and Slave devices you can
also enable **Master HASync No Overwrite**.

.. image:: img/Gateways-Config2.png
  :width: 100%
  :align: center
  :alt: Gateway configuration

Click **Save**. Next go to your already existing default Gateway and disable **Always Up** and enter a **Monitoring IP** outside of your network.

Go to **Routing -> Routes -> Routing Tables** and click **Edit** on your Main table. Add your newly created gateway in the 
Gateway section and assign a priority (lower numbers represent higher priorities).

.. image:: img/Gateways-Config3.png
  :width: 100%
  :align: center
  :alt: Gateway configuration

Policy Routing
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Routing tables can be used to create complex yet easy to maintain configurations in your VT AIR. You can for example route
traffic through your main ISP (while the connection is up) but route your VoIP phone service through your secondary ISP. 

To configure a setup like this you need to create a gateway for each of your WAN connections. See :ref:`Multi-Gateway Setup`
for further details.

Go to **Routing → Routes → Routing Tables** and click **Add** to create a new Routing table. Under Gateways add your secondary 
gateway but not your primary gateway if your VoIP traffic is only allowed to be routed through your secondary ISP's connection.
Click **Save**.

Go to **Firewall → Rules → WAN** and click **Add**. Configure a new Firewall Rule (:ref:`Firewall Rules (Forward and Input)`).
Your new rule should contain a specific condition that acts as a switch between the different routing tables. If your phones 
have their own subnet for example select their subnet in the Source section. Your new rule should also be added to the *Top*.

In the **Advanced Settings** Panel you can select your new Routing table under **Routing Table**. Also consider activating the
**Routing Table Reverse Main** option. Unlike your Main table your new table does not contain automatically created routes based on your interface 
configuration. So traffic might not have a route to flow in the reverse direction except you manually create a route in your new
table or you force your VT AIR to use the Main table for the reverse direction (**Routing Table Reverse Main** option).