Low Latency DOCSIS technology (LLD) is a specification developed by CableLabs in collaboration with DOCSIS vendors and cable operators that tackles the two main causes of latency in the network: queuing delay and media acquisition delay. LLD introduces an approach wherein data traffic from applications that aren't causing latency can take a different logical path through the DOCSIS network without getting hung up behind data from applications that are causing latency, as is the case in today’s Internet architectures. This mechanism doesn't interfere with the way applications share the total bandwidth of the connection, and it doesn't reduce one application's latency at the expense of others.
In addition, LLD improves the DOCSIS upstream media acquisition delay with a faster request-grant loop and a new proactive scheduling mechanism. LLD makes the internet experience better for latency sensitive applications without any negative impact on other applications.
Users of current DOCSIS 3.1 equipment experience typical round trip latency performance of around 10ms on the Access Network link. However, with normal usage patterns, the link can experience delay spikes of 100 ms or more. LLD systems can deliver a consistent 1 ms delay on the DOCSIS network for traffic that isn’t causing latency, imperceptible for nearly all such applications. The experience will be more consistent with much smaller delay variation.
LLD functionality can be deployed by field-upgrading DOCSIS 3.1 cable modem and cable modem termination system devices with new software.
The technology includes tools that enable automatic provisioning of these new services, and it also introduces new tools to report statistics of latency performance to the operator.
Cable operators, DOCSIS equipment manufacturers, and application providers will all have to act in order to take advantage of LLD technology. This paper explains the technology and describes the role that each of these parties plays in making LLD technology a reality.