  Stability is an important issue in order to characterize the performance of a
network, and it has become a major topic of study in the last decade. Roughly
speaking, a communication network system is said to be stable if the number of
packets waiting to be delivered (backlog) is finitely bounded at any one time.
  In this paper, we introduce a new family of combinatorial structures, which
we call universally strong selectors, that are used to provide a set of
transmission schedules. Making use of these structures, combined with some
known queuing policies, we propose a packet-oblivious routing algorithm which
is working without using any global topological information, and guarantees
stability for certain injection rates. We show that this protocol is
asymptotically optimal regarding the injection rate for which stability is
guaranteed.
  Furthermore, we also introduce a packet-oblivious routing algorithm that
guarantees stability for higher traffic. This algorithm is optimal regarding
the injection rate for which stability is guaranteed. However, it needs to use
some global information of the system topology.
