# Example: using QoS to prepare for ISP breakdown

Company B decides to use Multi-Link to ensure high availability of network connections for important business communications.

The company, an engineering subcontractor, is concerned about two types of connections:

- A VPN connection they have for accessing the internal tools and resources of an important client when doing work for them.
- HTTPS connections to the extranet server that the company’s clients use to check the status of projects.

The company has a tight budget, and the cost of having enough bandwidth in both links even during peak hours is deemed too high. They decide that only the two most important types of traffic must get through if one ISP link goes down during peak hours. The company determines that 500 kbps is enough to handle those connections, so they subscribe to 512 kbps links from two different ISPs. None of the communications are especially time-critical, so the company decides not to prioritize the traffic.

Then the administrators:

1. Create a QoS Policy and two QoS Classes, called VPN and Extranet.
2. Create the QoS rules for the important connections by filling in the following cells:

   Table 1. QoS rules in QoS Policy for Company B
   QoS Class | Guarantee
   --- | ---
   VPN | 400
   Extranet | 100

3. Add the QoS Class “VPN” to the VPN rule for outbound traffic in the Engine’s Access rules.
4. Add the QoS Class “Extranet” to the Access rule that allows outbound connections from the company extranet.
5. Define the types of throughput and select the custom QoS Policy to be used for the Physical Interfaces that correspond to the ISP links on the engine.
6. Refresh the policy of the engine.