On the Effects of the Wide-Spread Deployment of Route Control Products and Overlay Routing Services (Aditya Akella, CMU) =============================================================== Recent years have seen route control and overlay routing products that allow users and end-networks to select wide-area paths for their transfers in a more informed manner. For example, multihomed subscribers at the edge of the network are increasingly employing route control products (e.g., RouteScience's "Path Control"). Similarly, customers of Akamai's SureRoute service receive access to a large, diverse overlay network to route traffic on. The primary motivation for these products is to provide end-network-based mechanisms for optimizing wide-area performance and reliability. While the deployment of these products and services is not very widespread today, we expect it to grow rapidly over the coming years. At the same time, the deployment of such route control mechanisms has given rise to concerns about their impact on the general well-being (e.g. the stability of routing and network load) of the network. For this reason, the questions below are critical to our understanding of where the state-of-the-art in end-to-end routing and route selection lies today and where it is headed in the foreseeable future: - What is the impact of the deployment of route control mechanisms and services on the operation of ISP networks and on the efficient functioning of the Internet as a whole? - Would these products cause route or traffic instability in the Internet and if so, to what extent? - What new mechanisms do we need to put in place to counter the potential ill-effects? These questions can be addressed via a combination of measurement and analysis. The first step here is to accurately measure prevalent end-network practices for achieving intelligent route control and then build models for such end-network behavior. It is also crucial to understand, in general, what the best end-network strategies are for improving performance and resilience. This may help influence (and possibly, model) future product design too. The next step is to study the impact that both limited and wide-spread deployment of route control products can have on network operation. Since these products are not overly popular amongst end-networks today, this question cannot be answered using traditional measurement-based approaches. However, modeling, simulation and analysis could give us the answers we are looking for. One useful tool is game theory. The interaction between various intelligent end-networks and the Internet can be modeled as a game in which the end-networks are selfish agents trying to individually maximize a local goal, such as observed performance. The models for end-network behavior constructed above could prove very useful in such an analysis. If the above analysis shows that deployment of route control does not impact the stability of routes in a negative manner, network traffic and the efficient operation of the network as a whole, then we need not be too concerned about the proliferation of route control products. If, on the other hand, the analysis shows that these products can have a negative impact on how well the network functions, then we may have to work on measures to counter the ill-effects. Stated otherwise, "aggressive" end-network behavior must be sufficiently penalized and thereby discouraged. One way to achieve the negative incentives described above is to design novel pricing schemes (which may involve rewriting SLAs) to ensure that end-networks offer somewhat fixed, predictable load to their provider networks. The SLAs could be coupled with policing schemes at the ingresses of ISP networks which could, for example, rate-limit traffic or drop packets to discourage a particular choice of routes made by the end-network. Such schemes could help strike the right balance between the end-networks' attempts to improve performance and resilience, and the carriers' goal of ensuring stable traffic and routes, by factoring in economic benefit as the key incentive for socially conformant behavior. To summarize, it is unclear yet whether widespread use of route control products will disturb the stability of the operation of the Internet. This issue should be further explored by first identifying the various ways in which end networks can impact stability, then understanding the extent of the ill-effects, and finally designing pricing-based mechanisms to contain the ill-effects.