In this paper, we explore the use of end-to-end unicast traffic measurements to estimate the delay characteristics of internal network links. Experiments consist of back-to-back packets sent from a sender to pairs of receivers. Building on recent work [11,5,4], we develop efficient techniques for estimating the link delay distribution. Moreover, we also provide a method to directly estimate the link delay variance, which can be extended to the estimation of higher order cumulants. Accuracy of the proposed techniques depends on strong correlation between the delay seen by the two packets along the shared path. We verify the degree of correlation in packet pairs through network measurements. We also use simulation to explore the performance of the estimator in practice and observe good accuracy of the inference techniques.