Efficient Token-Based Control in Rings ∗†

In this paper we deal with the efficiency of token-based strategies for the basic problem of controlling the allocation of a shared resource in a ring of n processing entities. We propose new protocols that allow a bounded number of exchanged messages per access request to the resource, while this amount is unbounded for classical solutions. We also guarantee all the requests to be served within a maximum delay. The new proposed protocols are request-message-based strategies, in that a process entity sends a message to “inform ” the token of the access request