Example: ensuring quality of important communications

In this example, Company A has two offices, one in Italy and one in France. The company has decided to replace phone lines with VoIP telephony.

The illustration shows the two offices and the traffic between them. Telephone and email connections are an important tool for the employees, who use these services to communicate with team members at the other office. Also, employees at the Italian office must be able to use web-based tools at the French site. The administrators determine the priorities as follows:

The VoIP streaming audio is not only important, but it is also a time-critical service. VoIP streaming audio must have the highest priority.
Even though business email is important, email does not need to be delivered immediately after it has been sent. This traffic can be assigned a lower priority.
The web-based services are not time-critical, but delays and time-outs can annoy employees. The company decides to give these services a lower priority than VoIP, but a higher priority than email. It is not necessary to define a specific QoS Class for the medium-priority traffic because all traffic that is not classified is assigned a medium priority.

The internal networks are fast, so there is no need to implement QoS Policies for those interfaces. Only interfaces connected to the Internet need a QoS Policy. The administrators decide that the same QoS Policy can be used at both sites, and that the default elements and the default Prioritize policy are suitable.

So now they:

Add the QoS Class “High Priority” to Access rules that permit VoIP traffic.
Add the QoS Class “Low Priority” to Access rules that permit email traffic.
Define the QoS Policy Prioritize to be used on the interfaces connected to the Internet at both sites. They also define the types of interface throughput.
Refresh the policies of both firewalls.