Kelly Dorset, Head of Products and Digital Care, Plusnet [UK] explains in a post to lovemoney that ".. traffic management is often seen in a negative light with many in the industry, technology media and broadband users viewing it as an unnecessary slow down on services to stop users downloading lots of bandwidth. Here at Plusnet [here], that couldn’t be further from the truth. We’re big fans of traffic management and truly unlimited broadband and we offer them both at the same time. Traffic management, otherwise known as traffic prioritisation, is applied to all Plusnet’s broadband products and ensures that real time applications like gaming and streaming don’t get interrupted when more than one person is downloading at the same time".
Plusnet traffic management policies are explained here and shown below ("the systems identify traffic and assign it to one of six priority queues; Titanium is the highest priority").
The ISP mentions that "Some applications not using the standard port may not be identified correctly by our system, as we use DPI to identify applications on the network. These applications may be classified as 'other' traffic in which case a lower priority may apply"
|Plusnet Traffic management Policies|
See also "[Ofcom] UK Traffic Management; P2P Might be Reduced by 99%" - here and "Plusnet: Troubles with Traffic Management System" - here.
"Plusnet prioritises certain types of traffic to ensure there is enough bandwidth, or data, available for each activity to be performed without interruption. Plusnet gives streaming games and video high priority to ensure they don't buffer or lag. For example, if you’re making a video call to relatives on the other side of the world, you don’t want the picture of your suntanned beloved to break up"
See "Why broadband traffic management is a good thing" - here.