Rationality and Self-Interest in Peer to Peer Networks

Much of the existing work in peer to peer networking assumes that users will follow prescribed protocols without deviation. This assumption ignores the userr's ability to modify the behavior of an algorithm for self-interested reasons. We advocate a different model in which peer to peer users are expected to be rational and self-interested. This model is found in the emergent fields of Algorithmic Mechanism Design (AMD) and Distributed Algorithmic Mechanism Design (DAMD), both of which introduce game-theoretic ideas into a computational system. We, as designers, must create systems (peer to peer search, routing, distributed auctions, resource allocation, etc.) that allow nodes to behave rationally while still achieving good overall system outcomes. This paper has three goals. The first is to convince the reader that rationality is a real issue in peer to peer networks. The second is to introduce mechanism design as a tool that can be used when designing networks with rational nodes. The third is to describe three open problems that are relevant in the peer to peer setting but are unsolved in existing AMD/DAMD work. In particular, we consider problems that arise when a networking infrastructure contains rational agents.Engineering and Applied Science

Specification Faithfulness in Networks with Rational Nodes

It is useful to prove that an implementation correctly follows a specification. But even with a provably correct implementation, given a choice, would a node choose to follow it? This paper explores how to create distributed system specifications that will be faithfully implemented in networks with rational nodes, so that no node will choose to deviate. Given a strategyproof centralized mechanism, and given a network of nodes modeled as having rational-manipulation faults, we provide a proof technique to establish the incentive-, communication-, and algorithm-compatibility properties that guarantee that participating nodes are faithful to a suggested specification. As a case study, we apply our methods to extend the strategyproof interdomain routing mechanism proposed by Feigenbaum, Papadimitriou, Sami, and Shenker (FPSS) [7], defining a faithful implementation.Engineering and Applied Science

Using Redundancy to Improve Robustness of Distributed Mechanism Implementations

This paper introduces computation compatibility and communication compatibility as requirements for a distributed mechanism implementation. Just as payments are used to create incentive compatible mechanisms, some technique must be used to create computation/communication compatible mechanisms. This paper explores computation redundancy and communication redundancy as two such techniques. This paper uses interdomain routing as an example domain, and considers where redundancy can succeed and fail in addressing cheating with respect to computation and communication.Engineering and Applied Science

Faithfulness in Internet Algorithms

Proving or disproving faithfulness (a property describing robustness to rational manipulation in action as well as information revelation) is an appealing goal when reasoning about distributed systems containing rational participants. Recent work formalizes the notion of faithfulness and its foundation properties, and presents a general proof technique in the course of proving the ex post Nash faithfulness of a theoretical routing problem [11].In this paper, we use a less formal approach and take some first steps in faithfulness analysis for existing algorithms running on the Internet. To this end, we consider the expected faithfulness of BitTorrent, a popular file download system, and show how manual backtracing (similar to the the ideas behind program slicing [22]) can be used to find rational manipulation problems. Although this primitive technique has serious drawbacks, it can be useful in disproving faithfulness.Building provably faithful Internet protocols and their corresponding specifications can be quite difficult depending on the system knowledge assumptions and problem complexity. We present some of the open problems that are associated with these challenges.Engineering and Applied Science

Evaluating DHT-Based Service Placement for Stream Based Overlays

Stream-based overlay networks (SBONs) are one approach to implementing large-scale stream processing systems. A fundamental consideration in an SBON is that of service placement, which determines the physical location of in-network processing services or operators, in such a way that network resources are used efficiently. Service placement consists of two components: node discovery, which selects a candidate set of nodes on which services might be placed, and node selection, which chooses the particular node to host a service. By viewing the placement problem as the composition of these two processes we can trade-off quality and efficiency between them. A bad discovery scheme can yield a good placement, but at the cost of an expensive selection mechanism. Recent work on operator placement [3, 9] proposes to leverage routing paths in a distributed hash table (DHT) to obtain a set of candidate nodes for service placement. We evaluate the appropriateness of using DHT routing paths for service placement in an SBON, when aiming to minimize network usage. For this, we consider two DHT-based algorithms for node discovery, which use either the union or intersection of DHT routing paths in the SBON, and compare their performance to other techniques. We show that current DHT-based schemes are actually rather poor node discovery algorithms, when minimizing network utilization. An efficient DHT may not traverse enough hops to obtain a sufficiently large candidate set for placement. The union of DHT routes may result in a low-quality set of discovered nodes that requires an expensive node selection algorithm. Finally, the intersection of DHT routes relies on route convergence, which prevents the placement of services with a large fan-in.Engineering and Applied Science

Two Auction-Based Resource Allocation Environments: Design and Experience

Many computer systems have reached the point where the goal of resource allocation is no longer to maximize utilization; instead, when demand exceeds supply and not all needs can be met, one needs a policy to guide resource allocation decisions. One natural policy is to seek efficient usage, which allocates resources to the set of users who have the highest utility for the use of the resources. Researchers have frequently proposed market-based mechanisms to provide such a goal-oriented way to allocate resources among competing interests while maximizing overall utility of the users.Engineering and Applied Science

Using Redundancy to Improve Robustness of Distributed Mechanism Implementations

This paper introduces computation compatibility and communication compatibility as requirements for a distributed mechanism implementation. Just as payments are used to create incentive compatible mechanisms, some technique must be used to create computation/communication compatible mechanisms. This paper explores computation redundancy and communication redundancy as two such techniques. This paper uses interdomain routing as an example domain, and considers where redundancy can succeed and fail in addressing cheating with respect to computation and communication