We describe ways in which the transmission control protocol of the Internet may evolve to support heterogeneous applications. We show that by appropriately marking packets at overloaded resources and by charging a fixed small amount for each mark received, end-nodes are provided with the necessary information and the correct incentive to use the network efficiently.

We solve a shortest path problem that is motivated by recent interest in pricing networks or other computational resources. Informally, how much is an edge in a network worth to a user who wants to send data between two nodes along a shortest path? If the network is a decentralized entity, such as the Internet, in which multiple self-interested agents own different parts of the network, then auctionbased pricing seems appropriate. A celebrated result from auction theory shows that the use of Vickrey pricing motivates the owners of the network resources to bid truthfully. In Vickrey's scheme, each agent is compensated in proportion to the marginal utility he brings to the auction. In the context of shortest path routing, an edge's utility is the value by which it lowers the length of the shortest path---the difference between the shortest path lengths with and without the edge. Our problem is to compute these marginal values for all the edges of the network efficiently. The na ve method requires solving the single-source shortest path problem up to n times, for an n-node network. We show that the Vickrey prices for all the edges can be computed in the same asymptotic time complexity as one single-source shortest path problem. This solves an open problem posed by Nisan and Ronen [12]. 1.

ABSTRACT Internet applications and users have very diverse quality-of-service expectations, making the same-service-to-all model of the current Internet inadequate and limiting. There is a widespread consensus today that the Internet architecture has to be extended with service differentiation mechanisms, so that certain users and applications can get a better service than others at a higher cost. One approach, referred to as absolute differentiated services, is based on sophisticated admission control and resource reservation mechanisms in order to provide guarantees or statistical assurances for absolute performance measures, such as a minimum service rate or a maximum end-to-end delay. Another approach, which is simpler in terms of implementation, deployment, and network manageability, is to offer relative differentiated services between a small number of classes of service. These classes are ordered based on their packet forwarding quality, in terms of per-hop metrics for the queueing delays and packet losses, giving the assurance that higher classes are better than lower classes. The applications and users, in this context, can dynamically select the class that best meets their quality and pricing constraints, without a priori guarantees for the actual performance level of each class. The relative differentiation approach can be further refined and quantified using the Proportional Differentiation Model. This model aims to provide the network operator with the `tuning knobs ' for adjusting the quality spacing between classes, independent of the class loads. When this spacing is feasible in short timescales, it can lead to predictable and controllable class differentiation, which are two important features for any relative differentiation model. The proportional differentiation model can be approximated in practice with simple forwarding mechanisms (packet scheduling and buffer management), that we briefly describe here.

Can high quality be provided economically for all transmissions on the Internet? Current work assumes that it cannot, and concentrates on providing differentiated service levels. However, an examination of patterns of use and economics of data networks suggests that providing enough bandwidth for uniformly high quality transmission may be practical. If this turns out not to be possible, only the simplest schemes that require minimal involvement by end users and network administrators are likely to be accepted. On the other hand, there are substantial inefficiencies in the current data networks, inefficiencies that can be alleviated even without complicated pricing or network engineering systems.

This paper looks at ways of providing Quality of Service to users based on a simple pricing scheme. It is primarily aimed at elastic traffic, and it is users rather than the network who define the flow control schemes. A framework for assesing schemes and algorithms via a distributed game is presented.

Differentiated services for the Internet are undergoing intensive development. It is widely accepted that they will require usage sensitive pricing. The Paris Metro Pricing (PMP) proposal is to rely on pricing alone to provide differentiated services. PMP is the simplest differentiated services system in terms of complexity.

This paper introduces a novel feedback arrangement, termed re-feedback. It ensures metrics in data headers such as time to live and congestion notification will arrive at each relay carrying a truthful prediction of the remainder of their path. We propose mechanisms at the network edge that ensure the dominant selfish strategy of both network domains and endpoints will be to set these headers honestly and to respond correctly to path congestion and delay, despite conflicting interests. Although these mechanisms influence incentives, they don’t involve tampering with end-user pricing. We describe a TCP rate policer as a specific example of this new capability. We show it can be generalised to police various qualities of service. We also sketch how a limited form of re-feedback could be deployed incrementally around unmodified routers without changing IP.

Resource allocation and accountability keep reappearing on every list of requirements for the Internet architecture. The reason we never resolve these issues is a broken idea of what the problem is. The applied research and standards communities are using completely unrealistic and impractical fairness criteria. The resulting mechanisms don’t even allocate the right thing and they don’t allocate it between the right entities. We explain as bluntly as we can that thinking about fairness mechanisms like TCP in terms of sharing out flow rates has no intellectual heritage from any concept of fairness in philosophy or social science, or indeed real life. Comparing flow rates should never again be used for claims of fairness in production networks. Instead, we should judge fairness mechanisms on how they share out the ‘cost ’ of each user’s actions on others.

Eliciting truthful responses from self-interested agents is an important problem in game theory and microeconomics, and it is studied under mechanism design or implementation theory. Truthful mechanisms have received considerable interest within computer science recently for designing protocols for Internet-based applications, which typically involve cooperation of multiple selfinterested agents. A cornerstone of the mechanism design field is the Vickrey mechanism, or more generally the class of Vickrey-Clarke-Groves mechanisms. These mechanisms are known to be incentive-compatible, meaning that rational agents maximize their utility by truthfully revealing their preferences. In the Vickrey-Clarke-Groves (VCG) mechanism, each agent receives a "payment" for his participation, and this payment is proportional to the added "value" he brings to the system. Implementing the VCG mechanism often requires solving a (non-trivial) optimization problem n + 1 times, once with all agents, and once corresponding to each agent's deletion to determine his incremental value. An important algorithmic challenge is to reduce this computational overhead.

Over the past couple of decades, the Internet has rapidly evolved from a collaborative social experiment to an agglomerate of competing commercial providers. This shift has helped maintain growth and has turned the Internet