By Karthik Sundaresan, Greg White & Steve Glennon, CableLabs
Low latency is gaining importance in the internet experience. Low Latency is being approached as an end to end solution by operators. This includes Wi-Fi links in the home, DOCSIS links in the access network and core network segments. Providing lower end to end latency is a top priority for operators in the coming years. Measuring the latency in the network then becomes a vital requirement.
Operators (and 3rd party speed-test websites) have metrics on latency which they have reported and discussed with the community. Yet there is confusion surrounding the latency numbers and the ability to compare them between networks. The language and meaning of latency metrics (latency vs jitter, one way vs round-trip, average vs 99th percentile), the latency measurement methods, what is being measured and when (peak vs off-peak periods), are varied. This paper provides clarity around these topics and discusses latency measurement architectures as well as best in class measurement tools to streamline latency measurement for the cable industry.
Operators want the ability to measure the difference in latency that is actually being delivered, before and after they deploy a new technology in their network, like DOCSIS 3.1 AQM, Low Latency DOCSIS, Low Latency WiFi etc. The latency portion of measurement reports (e.g. FCC's Measuring Broadband America initiative) are not optimal, and without a consistent measurement approach to latency, this could become a customer perception problem for the internet service providers. For new technologies that differentiate traffic, there are also questions around how latency for unmarked traffic vs marked traffic can be measured and reported. Operators will be asked to help troubleshoot latency issues and it will be important for them to identify latency within their networks vs. outside of their networks. This paper discusses the latency measurement frameworks which an MSO can integrate into their network deployment.