Delay Characterization of Cable Access Networks

This letter presents a detailed characterization of the transmission delay in cable modem (CM) access networks. We analyze data obtained from measurements on operational access networks, examining both a moderately-loaded and a heavily-loaded CM network. We find that the medium access control algorithm used in CM networks results in a multimodal delay distribution, with measured delays clustered around a few discrete values. In the heavily-loaded CM network, a significant fraction of packets experienced delays that were multiple times larger than the average. The results imply that mean delay is a poor metric for measuring the performance of CM networks, especially when the network is heavily loaded