Although P2P traffic has shown tremendous growth in recent years, it is forecast to decline as an overall proportion of internet traffic by 2014 – accounting for 17%, according to Cisco’s annual Visual Networking Report. But, it’s still a problem for network providers and users – and evidently accounts for more than 50% of mobile broadband traffic in some networks – and needs to be addressed as other applications grow in popularity.
Generally speaking, the problem is worse in the upstream direction, as resources are scarcer than in the downstream. Once a user has installed a P2P client on their device, it uploads autonomously – someone else requesting content previously downloaded might receive it from a user without their active involvement. So, the content could be pulled from their device (i.e. consuming upstream resources) while the user is engaged in a different activity that will be affected by it, such as a video call.
In the downstream direction, the user might be streaming video and downloading P2P at the same time, which will consume downstream resources and cause contention. Theoretically, that’s more under user control and hence less of an issue.
Since P2P traffic such as BitTorrent depends on regular acknowledgements from the requesting device, it’s possible to control delivery by limiting acknowledgement of receipt. Rather than throttling traffic in the network, by which time it’s already caused a problem, adding control software to subscriber devices represents a more efficient means to control and restrict access to services on a per user basis, allowing different applications to be prioritised and to ensure those which generate revenue receive the highest priority. It’s not that network operators need to kill P2P, but rather that they need to find a way to live with it effectively. Adding prioritisation software to subscriber devices will ensure QoS where it’s required and fair treatment for competing applications.