ReMoS: A Resource Monitoring System for Network-Aware Applications

Network-aware applications can adjust their resource demands in response to changes in the availability of resources. Such applications must be able to obtain information about the status of the network resources. Providing such information to an application is conceptually simple, yet de ning an interface that addresses the needs of applications, as well as the realities of current and future networks, is far from easy. The Remos interface described in this paper allows network-aware applications to obtain information about network capabilities and network status. Interesting network informationmay be generated by the network hardware (switches), the network interface, or the network software, and is often in a system-speci c format. Further, network architectures signi cantly di er in their ability to provide such information in a timely and accurate manner. Remos provides a standard interface format that is independent of the details of any particular type of network. When hosted on an advanced network architecture, Remos provides access to accurate status and capability information. On legacy networks, Remos provides as much information as is feasible, using best-e ort approximation where appropriate. Using Remos, network-aware applications can be written independent of any particular network architecture, yet have the ability to tune their execution behavior to the dynamic state of the network. In this paper we motivate and describe the Remos interface. We also sketch our rst implementation of the interface for an IP-based testbed. Our experience in de ning and implementing Remos indicates that providing accurate feedback in an network-independent manner is a signi cant challenge and we identify a number of areas for future work. The network-independent Remos interface establishes a framework that can form the basis for further research.