By Eric Tijerina, Midco; Jeff Shields, Midco; Matt Zerfas, Midco; Karthik Sundaresan, CableLabs
Passive Optical Networks (PON) and Hybrid Fiber Coax (HFC) networks are commonly deployed for delivering Internet data, voice, and video services to subscribers. Operators in the cable industry would like to understand the real-world latency numbers across access technologies to ultimately affect the customer experience. This paper will present latency measurements taken across production networks. It will analyze the impact of enabling LLD (Low-Latency DOCSIS®) architecture across different HFC architectures commonly used in different MSO environments. This includes legacy/traditional DOCSIS networks as well as DAA (specifically RPHY) nodes.
The data gathered will be primarily focused on measured latency benefits when enabling AQM (Active Queue Management) and ASF (Aggregate Service Flows) - features of LLD in DOCSIS 3.1. The impact of enabling PGS (Proactive Grant Service), another key component of LLD, will be estimated to the extent possible. The results of our testing on the production cable plant will be compared against real world PON deployments utilizing the same tools and metrics. The measurements will reasonably assess the impact of different IP DSCP and ECN values and how those packets are treated in the network to improve customer quality of experience (QoE). We will also share some results on the latency measurements on our core network. This paper will give the cable operator community a good understanding of network latencies as well as the benefits of enabling technologies like LLD.