Technical measures (part IV): bandwidth shaping

This week Future of Copyright will devote specific attention to technical measures against piracy that can be employed by ISPs. Today we discuss the pros and cons of  protocol and port blocking.

Bandwidth shaping and throttling are similar to protocol and port blocking in that they are basically ISP interventions in network traffic. Bandwidth shaping and throttling are often intended to safeguard quality of service and network security. As opposed to protocol or port blocking, however, file-sharing connections are not severed but temporarily assigned a lower priority, with a corresponding decrease in data transfer speed. This (temporary) decrease in P2P traffic ensures sufficient bandwidth for time-critical applications such as video streaming, VoIP and web traffic.

To implement bandwidth shaping and throttling effectively, ISPs should be capable of distinguishing between different types of traffic. Deep Packet Inspection (DPI) is used alongside protocol recognition as a method to identify traffic types. DPI technology not only enables ISPs to inspect IP packet headers (which contain information on traffic type, sender and recipient), but also the data contained within the packet (the so-called payload). In this manner, traffic types can be determined (more) clearly. ISPs primarily use DPI to manage network traffic more efficiently and identify malicious IP packets that can possibly be used to orchestrate attacks on their networks.

The use of Deep Packet Inspection is controversial because it allows ISPs to search through communications, which may potentially constitute an invasion of the subscribers' right to privacy. Because of this, ISPs are reluctant to use this technology on behalf of third parties such as governments or entertainment industries. The question is whether ISPs can indeed be said to 'peek'. Examining the contents of one single packet suffices to establish the type of protocol involved. In case of content recognition, a small number of packets are enough to determine whether the contents are copyrighted or not. Nevertheless, examining IP packet payloads is potentially a more invasive measure than checking headers and should therefore be applied with due consideration.