It is shown that, for a ternary feedback random access channel with a Poisson arrival process,

is an upper bound to the throughput for all "degenerate intersection" algorithms (DIA\´s) and first-come first-served algorithms (FCFSA\´s). As a by-product, the nested FCFSA with the largest throughput is found for the random access channel with a Bernoulli arrival process with parameter

. For

, this algorithm has the highest throughput over all DIA\´s and FCFSA\´s. Lastly, it is shown that. for some values of

, a non-DIA, non-FCFSA has a higher throughput than the optimum DIA or FCFSA.