Wireless metrics over SNMP - proposing an OpenWrt MIB, and should OpenWrt get a PEN?

[perceival percy]

Hi,

As part of my daily usage of OpenWrt I tried a few times using network
management tools like librenms. Unfortunately out of the box OpenWrt
exposes almost nothing about its wireless side over SNMP. snmpd
provides the usual interface/host/IP tables, but there's no
client count, channel, noise floor, tx/rx rate or SNR anywhere - the IEEE
802.11 MIB tree is a single stub OID. Anyone who wants this ends up bolting
on their own per-NMS extend scripts, so there's no common schema.

I've started working on a small wireless MIB and a net-snmp pass_persist handler
for it. It discovers radios/VAPs live from ubus/iwinfo, so there's nothing
per-interface to configure - you turn it on with one "config pass" section
in /etc/config/snmpd (option persist '1'), which net-snmp already supports.
The table is indexed by ifIndex so it lines up with the interfaces snmpd
already reports, and per VAP it exposes client count, frequency, noise
floor, tx/rx rate (min/avg/max), SNR, channel airtime utilisation and tx
power. Nothing in it is specific to the monitoring system I tested with -
any SNMP NMS can read it.

So far tested on a few different platforms (mostly dumb AP setup):
Qualcomm IPQ8065/IPQ8074 and MediaTek MT7981.

Two things I'd like the project's view on:

1. Would OpenWrt consider registering its own IANA enterprise number (PEN)?
It's free and quick now (RFC 9371). At the moment the MIB is parked under
LibreNMS's enterprise arc, since that's where I've been testing it, but that
is not necessarily the right home for an OpenWrt MIB - it should live under one
OpenWrt owns. That part only the project can do. Just to be clear I'm
not suggesting anyone
register something on OpenWrt's behalf.

2. Would you be open to shipping this as an optional feed package (the MIB
plus the pass_persist handler)? net-snmp itself stays untouched - the
package just drops in the config pass section and the script.

Happy to do the work and maintain it. The MIB, the handler and the matching
NMS-side discovery are in review here if you want to look:

  https://github.com/librenms/librenms-agent/pull/613
  https://github.com/librenms/librenms/pull/19347

Would be glad to hear whether the PEN idea makes sense to you, since that's
the piece I can't move on my own. Also one can envision expanding it
in the future beyond wireless stats so with proper anchor I am pretty
sure there are going to be other initiatives to expand monitoring
capabilities over SNMP.

Regards,
Kamil Bienkiewicz