As per Fizz FAQ:

Does Fizz apply Internet traffic management measures?

Yes, Fizz applies traffic management measures, but only from the user to the Internet (upload), and for the 120 Mbps access.* Certain conditions (see below).

Why does Fizz use Internet traffic management measures? 

Fizz wants to offer the best online experience to its members. Because the upload speed (from the user to the Internet) of the 120 Mbps access is high, Fizz uses traffic management measures to prevent some modems from slowing down the overall service, even momentarily.

What kind of traffic is targeted? 

Fizz does not target any particular type of traffic, nor any specific applications or protocols such as peer-to-peer file sharing. Only data uploads (from the user to the Internet) made with the 120 Mbps* access are subject to traffic management. Download traffic (from the Internet to the user) is not managed.

When and how does Fizz manage traffic on its network?

Every 15 minutes, a system checks the traffic rate of each upstream channel (typically, one upstream channel serves a few dozen modems).

If the traffic rate exceeds the threshold above which congestion occurs, the system identifies  the 120 Mbps* modems in that channel that are uploading a large amount of data. The upload capacity of these modems is then given a low-priority rating. Based on the severity and time during which the congestion persists, the upload speed of these modems may then be slowed down.

When the amount of data uploaded by the modems is diminished or the traffic on that channel reverts to a normal rate for which congestion is no longer an issue, the upload capacity prioritization will go back to normal, and speed is restored. Even when they are no longer prioritized, modems programmed for the 120 Mbps* access can use up all the upload bandwidth that other modems are not using, at a speed equivalent to their nominal speed.

*Available in restricted areas only. Please check service availability in your area.

The measures described above are implemented on an ongoing basis.