Traffic shaping, also known as "packet shaping," is the practice of regulating network data transfer to assure a certain level of performance, quality of service (QoS) or return on investment (ROI). The practice involves delaying the flow of packets that have been designated as less important or less desired than those of prioritized traffic streams. Regulating the flow of packets into a network is known as "bandwidth throttling." Regulation of the flow of packets out of a network is known as "rate limiting."
Traffic shaping is used for a number of purposes:
- Time-sensitive data may be given priority over traffic that can be delayed briefly with little-to-no ill effect.
- A large ISP (Internet service provider) may shape the traffic of an independent reseller.
- In a corporate environment, business-related traffic may be given priority over other traffic.
- An ISP may limit bandwidth consumption for certain applications to reduce costs and create the capacity to take on additional subscribers. This practice can effectively limit a subscriber's "unlimited connection" and is often imposed without notification.
- Traffic shaping could be an integral component of the proposed two-tiered Internet, in which certain customers or services would get traffic priority for a premium charge.
Traffic shaping is a frequent topic of debate between advocates of Net neutrality and proponents of a two-tiered system. ISPs often target peer-to-peer (P2P) file sharing programs such as BitTorrent. Advocates of Net neutrality argue (among other things) that Internet data packets should be treated impartially, without regard to their content, destination or source and that it is difficult to delay some types of traffic without unintentionally hampering others. Proponents of a two-tiered system, on the other hand, argue that there have always been different levels of Internet service and that a two-tiered system would enable more freedom of choice and promote Internet-based commerce.