Peer-to-peer (P2P) (news - alert) is a killer application that drives massive numbers of people to broadband. Wireless carriers are now launching faster packet networks, such as CDMA2000 1XEV-DO, (news - alert) as wireless replacement technologies. Thus, with wireless technology providing sustained packet rates similar to that of DSL (news - alert) -- and similar unlimited usage pricing models -- we will likely see a similar effect on wireless data traffic. Because of P2P’s attributes, wireless service providers must protect themselves against its propensity to degrade service and lock out subscribers as well as its potential to decrease revenue and increase costs.

The few customers who use P2P applications in wireless networks may not only spoil the experience of other users but also devastate current wireless business models. Because P2P software is indiscriminate in where it obtains content, it has a tendency to clog the network and, in particular, the access network. Worse, perhaps, is that while wireless networks are designed to drop devices after 20 seconds of inactivity, P2P applications continue to transmit packets of data and keep sessions active. Active sessions do not release wireless resources and make them available to other users. Thus, a small number of users with active P2P sessions could seriously degrade services provided to many other subscribers.

Equally dangerous from a service provider’s perspective is the loss of revenue from push-to-talk services. After all, if subscribers are using free P2P voice communications to speak to their circle of friends, why purchase push-to-talk services from their service providers? In short, P2P wireless applications threaten carriers with revenue loss and increased customer care and peering costs. Their subscribers face poor quality of service and unpredictable access to the wireless network.

Solutions

Encouragingly, there is a way to control costs and prevent P2P traffic from devouring revenue. In order to address these serious problems, service providers should consider granular user-based control systems that enable them to determine which subscribers are authorized to use specific services, such as P2P. Alternatively, they may consider unlimited premium service packages that allow all types of data services.

Making users Pay for What They Use

One approach that many service providers consider is to make users pay for what they consume. The service provider works out a financial model that gives a fixed usage capacity for customers either on a daily or monthly basis. Users are then free to do whatever they like, but once they go over this limit they incur over-usage charges. This requires careful planning and even more careful communication to customers. With careful planning, the majority of customers who do not use P2P extensively will have to pay nothing extra. One way to communicate this would be a phased approach in which users are shown extra charges they would incur under the new scheme for a few months before they are actually charged. However, as wireless P2P use grows and the number of P2P users increases, it is inevitable that service providers must introduce a method of controlling P2P traffic to ensure that all users obtain an optimum experience.

Technical Approaches to P2P Traffic Management

Managing P2P traffic is not particularly difficult from a technology perspective, but it can pose problems from a customer relations perspective if it is managed in an obvious manner. Too much management may result in carriers being condemned by lobby groups. But too little management of P2P can also have significant impact on wireless network performance and the experience of the vast majority of non-P2P users.

For those carriers that opt to exercise more control over P2P, there are a number of technological approaches available. All rely on a network element that is capable of identifying and controlling different traffic types associated with P2P at layer 7 in the Open Systems Interconnection (OSI) (news - alert) model. The key issue is how these elements are used and where they are placed in the network to establish maximum control with minimum disruption to legitimate traffic and users.

Proactive P2P Control

Perhaps the best technical approach is to drive control of P2P traffic by using policies based on knowledge of the user and current network capacity and availability. This approach allows for P2P use but does not allow it to overload available network capacity.

This approach requires the system to limit the total volume of P2P traffic to some total volume of the network. This keeps P2P traffic in check so it cannot adversely affect non-P2P users, but does mean that the P2P user experience can be variable: when the network is busy with other P2P users, the experience will be less than optimal.

Conversely, when there are fewer users, there will be more bandwidth available and the experience will be better. Allowing some P2P users to pay for more bandwidth for their P2P application can augment this model and generate additional revenue. Users selecting this option would receive a bigger share of the available bandwidth for P2P traffic, giving them a better experience and providing the carrier with a supplementary revenue stream.

Using this architecture, a carrier could manage and control P2P applications without eliminating the standard flat-rate model that is prevalent today in the market. P2P user experiences would be affected, but with the right traffic thresholds the impact could be minimal and only noticeable during periods of high usage. Since the system limits all P2P traffic including the search, upload and download of content, the network should just appear to be running slower for P2P traffic.

Bottom Line

Given its broadband popularity, users will most certainly use P2P it in wireless environments, particularly those that replace fixed line access. And it will likely be a major driver of wireless data traffic. But it can negatively impact network performance and cost, and be detrimental to the experience of non-P2P users. Thus it must be controlled. Technological solutions should be put in place to control and charge for the use of P2P in a way that is fair to users and delivers added revenue to service providers.

 Mark Denton is a Product Manager for Bridgewater Systems.

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