Systems without Cooperation
David Levin
Successful networked systems must account for potentially competing
interests: the Internet is no longer the cooperative, technological
playground it once was. The protocols are the rules relegating the
venue for this competition, but those rules often lack enforcement. I
will present the application of economics and trusted hardware to keep
participants in a networked system from deviating from the letter and
spirit of a protocol.
First, I will apply economic mechanism design to keep selfish users
from gaining at the expense of others. I will show that the popular
BitTorrent system uses, not tit-for-tat as widely believed, but an
auction to decide which peers to serve. This model captures known,
performance-improving strategies, and shapes or thinking toward new,
effective incentive mechanisms.
Second, I will apply trusted hardware to keep both selfish and
malicious users from "equivocating," or sending semantically
conflicting messages. I will present TrInc (Trusted Incrementer), a
small piece of trusted hardware intended for use in large-scale
distributed systems. With case studies and an implementation, I will
demonstrate that TrInc is a practical primitive for protecting a wide
range of systems.
These two examples together demonstrate the importance of aligning the
assumptions of economics and large-scale systems. Doing so allows us
to develop new mechanisms that foster cooperation among the otherwise
self-interested.
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