Recently, Harchol-Balter and Wolfe introduced the problem of determining the class S of queueing networks N for which NCF has smaller average delay than NEF. This problem has applications to bounding delays in packet-routing networks.
In this paper we consider the same problem, only restricted to the case of light traffic. We define SL to be the set of queueing networks N for which NCF has smaller average delay than NEF in the case of light traffic. We discover a sufficient criterion to determine whether a network N belongs to SL, where this criterion is extremely simple and easy to check. Using this criterion we are able to show that many networks belong to SL that were previously not known to belong to S. The significance of this result is that it suggests that many more networks are contained in S than has already been shown.