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DOCSIS CMTS Suggestions, Best Practices and Recommendations

Episode 25 Today is Friday January 27th and this is episode 25 of Get You Tech On – the cable industry’s #1 DOCSIS podcast.  I’m Brady Volpe, Founder of The Volpe Firm and Nimble This.  With us is the a man who is world famous in certain parts of the country, John Downey, CMTS Technical Leader at Cisco Systems, welcome John thanks for coming back again. Today’s episode is a good one.  I’ve accumulated a backlog of questions on DOCSIS CMTS optimization we will cover and likely to go off on any number of tangents.

Provide brief overview of DOCSIS CMTS best practices and optimization in regards to “new” commands & configurations.  Recommendations and deviations from default settings are based on typical cable plant architectures & design.  Recommendations may not apply in some scenarios.

More detailed information about DOCSIS CMTS features can be obtained from your DOCSIS CMTS vendor.  Topics listed in order as they appear when doing “show run” from Cisco cBR-8 CMTS

Let’s start out with a Question from Heather:

Heather writes:  Here is my situation: As you know there are 20 US ports on each card and two jumpers that plug in to those US ports. The US ports are grouped in 5’s so each jumper has 10 US carriers; U0-U9 on Jumper 1 and U10-U19 on Jumper 2.

My first node is using US0-US3 & DS0, the second node is using US4-US7 & DS1 and modems are locking on all 4 carriers. My third node on card 7/0 is using the last two cables from Jumper 1, US8 & US9 and the first two cables from Jumper 2, US10 & US11 & using DS2 but my modems are only locking on the first two US carriers and not seeing the other two on the third node. Any idea why?

<First Slide>  I have another question that comes in three parts.  Can you break down the flap list and how best to use it; what is the recommended best value for “cable modem max-cpe” and finally, is VoIP always guaranteed to flow on one downstream channel or is there a chance that it could get stripped across multiple bonded downstreams causing jitter and latency, maybe even packet loss?  Thanks for help.  -Jessy

<Slides 2 – 4> Bill writes: Hi Guys, keep up the great podcasts.  Can you help me out.  I’m struggling to get my DOCSIS 3 load balancing working correctly.   Can you go over the differences in all of the DOCSIS 3.0 load balancing commands?    Also it would be great if you could go over what you would recommend for load balancing.

<Slide 5> We are having problems with modems that go offline and then into DOCSIS 2.0 mode (just one downstream channel) when one of our 8 downstream channels becomes impaired.  Is there a way we can have a modem stay online with in downstream partial mode like it does in the upstream?  Thanks -Rick

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