By Hang Jin and Yubin Chen, Cisco Systems
The Remote DOCSIS Timing Interface (RDTI) is the timing specification standardized recently for R-PHY architecture. R-DTI leverages on IEEE1588v2 with a special profile for DOCSIS applications. This paper explains how R-DTI works and what are the requirements on the time/frequency synchronization between CCAP core and RPD to ensure proper DOCSIS operations. Two operation modes that are defined in RDTI, the NodeSlave mode and NodeMaster mode, are explained and their operations are illustrated. Tests are done in Cisco R-PHY Lab to validate R-DTI under various network conditions. Test results show that, with the commercial R-DTI solutions, the timing and frequency synchronization between CCAP core and RPD can be achieved within 5 minutes in all the test cases and CM can operate normally without any performance degradation after the synchronization is achieved.