Traffic Shaping
Protocol-level traffic shaping is a very effective tool for ISPs to reduce bandwidth consumed by P2P traffic and give other traffic a higher priority on their network. Traffic shaping — typically in-line network elements that inspect, prioritize, and sometimes redirect traffic — provides a mechanism to control the volume of traffic being sent into a network (bandwidth throttling) and the rate at which the traffic is being sent (rate limiting). However, since many subscribers use P2P services, limiting or completely blocking P2P traffic will lead to customer dissatisfaction and increased churn.
Recently, many ISPs have begun using traffic shaping to curb the usage of P2P file sharing by giving other traffic a higher priority on their network. Many have opted for traffic shaping to manage the usage of this bandwidth, either because they are unable to upgrade their bandwidth fast enough or as an alternative to upgrading their bandwidth.
Traffic-shaping strategy is being used for limiting and suppressing P2P traffic using specialized hardware or leveraging existing infrastructure. Traffic shaping usually manipulates the usage of limited network resources in order to allow service providers to control their operational expenses related to transit bandwidth. Shaping works by queuing, dropping, or prioritizing the traffic.
Traffic shaping introduces some significant challenges. Traffic shaping dramatically reduces P2P customers' response time of the network, increases network time-outs, and impacts user experience. Alienating a large and growing group of customers can and often does have negative business ramifications for the ISP — dramatically growing customer support costs and churn rates. Plus, P2P users will seek ways to circumvent traffic shaping through traffic masquerading, encryption, etc., triggering a war of attrition with ISPs. In addition, deep packet inspection technology used by traffic shaping is not content-aware — therefore indiscriminate shaping of bit-torrent traffic shall harm both emerging commercial and open uses of the protocol, potentially entangling ISPs in disputes in which they do not want to be entangled. Finally, shaping P2P traffic limits future ISP revenue opportunities from premium P2P services.
| Traffic Shaping | |
| Pros | Cons |
| Controls P2P impact on overall network | Can dramatically increase customer support and churn for P2P users |
| Can provide better experience for non-P2P subscribers | Damages ISP reputation as unfriendly to subscribers |
| Provides flexibility to throttle or eliminate P2P traffic | P2P users likely to circumvent traffic shapers (e.g., encrypted P2P traffic) |
| Implementation familiar to ISPs via in-line network devices | Reduces revenue opportunities from P2P |
