TROBADOR: Service Discovery for Distributed Community Network Micro-Clouds

Community networks are decentralized communication networks built and operated by citizens, for citizens. We consider service discovery for clouds in such community networks. The currently employed solutions for service discovery are static and are not able to follow the dynamics in cloud service provision. We propose a novel service discovery mechanism based on the common Linux tool Avahi combined with TincVPN, in which the VPN allows Avahi to reach nodes beyond the local link. The concept of the micro-cloud is introduced which contains the nodes reached with the extended broadcast domain of Avahi. We evaluate the performance of the proposed service discovery mechanism in a real community cloud deployment consisting of 25 geographically distributed nodes. In experiments with different settings and number of services, we measure the number of services discovered as a function of the discovery time. Our results show that while a client eventually discovers all the services, a significant time is needed to achieve a complete service discovery. The proposed mechanism therefore seems appropriate for the case of community clouds with many replicas of a sought service, where the fast discovery of just a few providers satisfies the requirements of a client. By applying standard Linux tools, an advantage of our solution is that it is by default available on most Linux distribution, which allows our solution to be easily used for real deployments.