Characterizing Physical-Layer Transmission Errors in Cable Broadband Networks
Packet loss rate in a broadband network is an important quality of service metric. Previous work that characterizes broadband performance does not separate packet loss caused by physical layer transmission errors from that caused by congestion. In this work, we investigate the physical layer transmission errors using data provided by a regional cable ISP. The data were collected from 77K+ devices that spread across 394 hybrid-fiber-coaxial (HFC) network segments during a 16-month period. We present a number of findings that are relevant to network operations and network research. We estimate that physical-layer errors can contribute to 12% to 25% of packet loss in the cable ISPs measured by the FCC's Measuring Broadband America project. The average error loss rates of different HFC network segments vary by more than six orders of magnitude, from O(10−6%) to O(1%). Users in persistently high-error-rate networks do not report more trouble tickets than other users.