ARRIS E6000 – Please note the ARRIS E6000 does not comply with the DOCSIS 3.1. spec – Section 9 of the DOCSIS 3.1 PHY specification, which includes upstream spectrum analysis for the E6000 D3.1 CMTS. ARRIS production software does not support the MIB’s with the exception of the software provided by ARRIS to Comcast only. If considering the E6000 please address this in advance with your ARRIS sales rep.  ARRIS is aware of their non-compliance with the DOCSIS 3.1 spec.

Update – “After much anticipation and hard work in the InGeNeOs working group at CableLabs, the CCAP PNM Upstream Triggered Spectrum Capture engineering change notice (ECN) has officially been published as of January 11, 2017. The updated management information base (MIB) list was made available in September 2016 and the DOCSIS 3.1 CCAP operations support system interface (OSSI) specification can be downloaded at” https://apps.cablelabs.com/specification/ccap-operations-support-system-interface-specification

CASA 10G CCAP CMTS – Update from CASA – “7.1.3 release we will give the customer the option to turn on the 24 tap eq via CLI, they can also turn it off if modem issue arise”.   Please contact CASA if you have any questions about this release.

If not using release 7.1.3 – CASA is not maintaining coefficients for taps beyond 16. They state maintaining taps 17 through 24 does not improve performance on their system. This is DOCSIS 2, 3 and 3.1 non compliant.  CASA is working to correct this.  However, we recommend that Operators discuss these issues with their sales rep in advance of purchase.

What does this mean for the operator? CMTS is not sending the coefficients 17 – 24 to the Cable Modem. This limits the ability for the Cable Modem to compensate for sever Group Delay and completely stops the Cable Modem from dealing with micro reflections / echo cavities greater then 765 feet. This is independent of PNM.

Group Delay compensation, in very severe (main tap compression (MTC) = 0.75 and greater) we do see taps > 16 being used to compensate for GD. Same thing for the case of a very severe multiple recursion. Energy from taps 17-20 would contribute to improving the problem.

Echo cavities for spans of cable beyond 765 ft for a 6.4 MHz upstream channel (9T cavity) or 1500 ft for a 3.2 MHz upstream channel. It is quite common to see spans of coax cable in the 1000’ range with a strong echo (i.e. micro-reflection) that is completely resolved by taps 17 through 24. No energy is observed in lower taps.

Also, the Casa CMTS is non-DOCSIS compliant per 6.2.16 Transmit Pre-Equalizer (from the DOCSIS 3.0 PHY spec) and 9.4.4 of the D3.1 PHY (should you decide to upgrade the 100G to D3.1).

With Casa CMTSs there is no post-eq data.