Hello,
After increasing the number of available cable downstreams on fiber node from 4 to 8 im experiencing Docsis Partial service status on all cable modems that are capable to work in 8x4 configuration (cisco). Instead of working in 8x4 mode all modems work only at 4x4 mode and report first four downstream channels in terms of frequency as impaired. Modems report that the reason for impairment is bad rcs.
Fiber node has 8 consecutive downstream channels.
CMTS is configured to support dynamic rcc, i already tried to setup additional static rcc with two 4 ds receive modules but it didnt help.
I would be grateful if You guys could point me in the right direction towards the root cause of the problem. What does it mean bad rcs? Is is CMTS side misconfiguration, cable modem misconfiguration, some other plant related problem ?
Thanks in advance
post a sanitized copy of your running config
Config in attachment. Problematic mac domain is mac 4 - downstream from 15/12 to 15/19. Modem use only downstream from 15/16 to 15/19, while 15/12 15/13, 15/14 and 15/15 are unused. Now i suspect its not Docsis 3.0 specific problem, because even D 2.0 modems dont use those downstreams. I will double check the plant.
Hi,
It looks you're using the same down frequency's from 15/8-11 and 15/12-15 interfaces.
You have to check isolation between transmitters; are they connected to the narrowcast ports ?
Darek
Hello again,
Yes downstreams use the same frequencies because they are part of separate mac domain and attached to separate fiber nodes.
I managed to solve the problem - signal entering fiber nodes from headend had quality issues - I should start troubleshooting from this but I was assured that signal was checked. So in the end the moral for me is that badrcs status can mean also RF issues.
Thanks for Your time guys.