  In this paper, we investigate random walk based token circulation in dynamic
environments subject to failures. We describe hypotheses on the dynamic
environment that allow random walks to meet the important property that the
token visits any node infinitely often. The randomness of this scheme allows it
to work on any topology, and require no adaptation after a topological change,
which is a desirable property for applications to dynamic systems. For random
walks to be a traversal scheme and to answer the concurrence problem, one needs
to guarantee that exactly one token circulates in the system. In the presence
of transient failures, configurations with multiple tokens or with no token can
occur. The meeting property of random walks solves the cases with multiple
tokens. The reloading wave mechanism we propose, together with timeouts, allows
to detect and solve cases with no token. This traversal scheme is
self-stabilizing, and universal, meaning that it needs no assumption on the
system topology. We describe conditions on the dynamicity (with a local
detection criterion) under which the algorithm is tolerant to dynamic
reconfigurations. We conclude by a study on the time between two visits of the
token to a node, which we use to tune the parameters of the reloading wave
mechanism according to some system characteristics.
