Selection and publication of network interface cards in multihomed pervasive computing devices

Many modern devices come with several, heterogeneous, network interface cards (NICs). However, simple operations like transferring data flows to the cheapest NIC or to one with enough Quality of Service (QoS) are awkward tasks on most Operating Systems. In this paper, we discuss the criteria to select the proper NIC for a given data flow. We also present a new Operating System service, called netqos, to publish data and figures of merit for these criteria. The main objective of netqos is providing relevant information to applications and middleware about NIC selection criteria, isolating them from the idiosyncrasies of the many QoS gathering tools and allowing to choose the proper NIC to fit their needs. We have built this new service as a synthetic file system for the Linux kernel. We describe our experiences in using it in a real-world scenario and the practical and inherent limitations of this approach.