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Cable DOCSIS 3.1 CCAP
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DTI for Modular CMTS L2TPv3 PW L2/L3 DTI Server: TimeCreator 1000 IP
M-CMTS Core L2 MAC DTI Client Edge QAM L1 PHY Cable Modem IP Net work L2TPv3 PW L2/L3 HFC DTI Server: TimeCreator 1000
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TP 5000 for Remote PHY DOCSIS 3.1
HFC CMTS core Core Cable Modem PTP Slave DS PHY US PHY Remote Physical Device RPD Clock CMTS Core Clock slave Ethernet CICN Stand-alone Grandmaster DTP
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TP 5000 for DOCSIS 3.1 Cable Labs recommends G.8275.2 PTP profile
No On Path Support required to meet performance No GPS/GNSS required for phase alignment of CMTS/RPD Redundant GMC in separate locations using BMCA Complex, reference switching and Phase alignment issues Redundant GMC (TP 5000) Simple engineering, L3 Unicast IP address No reference switching issues Cisco embedded GMC is not redundant PTP Slave Capacity Some CMTS will have up to 2,000 RPD TP 5000 is high capacity GMC If CMTS or vCMTS servers and RPD use separate GMCs GNSS or GPS will be required for the 1 millisecond phase alignment
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Critical Timing Application
CMTS to Remote PHY timing PTP used to generate clock at both locations Clocks must be aligned to within one millisecond Timing impact If PTP slaves at CMTS or RPD cannot get PTP from the GMC CMTS equipment will go to holdover on internal clock RPD equipment will go into holdover on internal clock CMTS and RPD clock will drift apart Time to one millisecond depends on quality of internal oscillator Typically less than one hour Results in Customer service issues Video and audio alignment Slow or degraded TV channel changes Video playout buffering issues resulting in poor quality video Packet loss Critical Timing Application requires redundant PTP GMC
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DOCSIS 3.1 CCAP Remote PHY CCAP Cable Labs Converged Access Platform
RPD Remote Physical Device CMTS Cable Modem Termination System DTP DOCSIS Timing Protocol Timing Requirements 1 Millisecond Phase Alignment Between the CMTS (or vCMTS server) and the RPD G PTP profile with no On Path Support Meets performance requirements Frequency 50 PPM Mobile Backhaul will add additional timing requirements More stringent (LTE-A, LTE-TDD) G PTP Profile Overlay Edge GMC with APTS PTP backup
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Summary DOCSIS 3.1 CCAP Cable Labs TP 5000
Requires 1 millisecond phase alignment CMTS (vCMTS servers) and RPD Support for Mobile Backhaul adds more stringent requirements Cable Labs Recommends G PTP Profile Will meet the performance requirements without Full On Path Support TP 5000 Fully redundant Cisco embedded GMC is not a redundant solution High Capacity Some CMTS locations will have more than 2,000 RPDs Simple engineering No BMCA L3 Unicast with IP address selection in TP5K
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