By Elías Chavarría Reyes, Ph.D. & John T. Chapman, Cisco Systems, Inc
CableLabs released the I01 SYNC specification on April 20, 2020. The SYNC specification describe show to build and deploy an IEEE 1588/PTP participant DOCSIS network. The SYNC specification is targeted at the new and evolving mobile backhaul market.
The core technology that makes timing work is the DOCSIS Time Protocol (DTP). DTP was introduced in DOCSIS 3.1 and described in but has not been deployed as of yet. The operation of DTP is not well understood and there are many new considerations in order to bring it from a specification to a deployed product. As a result of this strong interest by operators, there is a need to re-explore in detail several aspects of DTP, including:
- what DTP does,
- how it works,
- how it is calibrated,
- how it is used in a live system,
- how it interplays with other DOCSIS procedures,
- limitations, and tradeoffs.
The goal of this paper is to provide this detailed exploration of DTP and enable the Cable community to have a common understanding of DTP so they can confidently develop it and use it.