  We propose a group membership service for dynamic ad hoc networks. It
maintains as long as possible the existing groups and ensures that each group
diameter is always smaller than a constant, fixed according to the application
using the groups. The proposed protocol is self-stabilizing and works in
dynamic distributed systems. Moreover, it ensures a kind of continuity in the
service offer to the application while the system is converging, except if too
strong topology changes happen. Such a best effort behavior allows applications
to rely on the groups while the stabilization has not been reached, which is
very useful in dynamic ad hoc networks.
