I use LibreNMS regularly for my day job. While I primarily deal with wireless internet, we have a couple of small cable systems we manage as well. Older systems, rural, DOCSIS 2 CMTS, primarily old Surfboard modems and some Ubee.
As installed, LibreNMS will pick up general information about cable modems. Port info, traffic on those ports, response times, some log information — that’s about it. I wanted signal information, though, and eventually found some info online that made it easy for me to figure out how to capture that data and keep historical records. So, this short post is just that: the OIDs for a few data points on cable modems for SNMP data capture.
I’m not sure the entire list of cable modems these OIDs work with, but they are working on Surfboard SB5100,SB5101,SB5120, SB6180 as well as Ubee DDM3513, U10C018 and U10C035.
I found this info in a pdf called PNM Best Practices: HFC Networks (DOCSIS 3.0), page 161.
If the above .pdf disappears, leave a comment and I’ll see what I can do to find it again.
Adding custom OIDs to LibreNMS
If you’re using LibreNMS, you can add these by going to Edit / gear icon on the device main page, then click on ‘Custom OID’ on the right-side mid-menu.
When adding signal or frequency records, based on the above, be sure to enter the divisor so the outputs are in familiar formats. dBmV results should be divided by 10, and for display purposes, I found frequencies are better-displayed when as MHz vs hertz. For records like T3 timeouts and Lost Syncs, use the Counter data type.