Asymmetric Incentives in Peer-to-Peer Systems

In most application scenarios for Peer-to-Peer systems, in order to achieve an overall acceptable system performance an incentive scheme is required that motivates users to share as much as possible of their free resources Today most peers use connections of asymmetric links, such as A-DSL or cable modems. Therefore, users have significantly more download bandwidth than their available upload bandwidth. Applying this observation to incentive schemes suggests that one unit of upload bandwidth should be valued higher than one download unit. Using such an incentive scheme leads the economy of the system to inflation. The incentive scheme would finally collapse. However, by exhibiting the phenomenon of altruistic behavior altruistic peers would accumulate the waste amount of the incentive units. Thus, inflation might be avoided. Gathering the results of a detailed simulative approach, this paper shows how to balance asymmetric incentive schemes in order to avoid inflation.