Dissecting Last-mile Latency Characteristics

Abstract

Recent research has shown that last-mile latency is a key network performance indicator that contributes heavily to DNS lookup and page load times. Using a month-long dataset collected from 696 residential RIPE Atlas probes and 1245 SamKnows probes, we measure last-mile latencies from 19 ISPs (RIPE Atlas) in the US and the EU, and 9 ISPs (SamKnows) in the UK. We show that DSL deployments not only tend to enable interleaving on the last-mile, but also employ multiple depth levels that change over time. We also witness that last-mile latency is considerably stable over time and not affected by diurnal load patterns. Unlike observations from prior studies, we show that cable providers in the US do not generally exhibit lower last-mile latencies when compared to that of DSL. We instead identify that last-mile latencies vary by subscriber location and show that last-mile latencies of cable providers in the US are considerably different across the US east and west coast. We further show that last-mile latencies vary depending on the access technology used by the DSL modem wherein VDSL deployments show last-mile latencies lower than ADSL1/ADSL2+ broadband speeds. The entire dataset and software used in this study is made available to the measurement community.