First, you need to make sure the snmp work by using snmpwalk utility

  snmpwalk –v 2c -c public  snmp_server_ip

Second, make sure the hardware related stevdore plugins are registered in setup.cfg or entry_point.txt in your ceilometer package.

[ceilometer.poll.central]
energy = ceilometer.energy.kwapi:EnergyPollster
hardware.cpu.load.15min = ceilometer.hardware.pollsters.cpu:CPULoad15MinPollster
hardware.cpu.load.1min = ceilometer.hardware.pollsters.cpu:CPULoad1MinPollster
hardware.cpu.load.5min = ceilometer.hardware.pollsters.cpu:CPULoad5MinPollster
hardware.disk.size.total = ceilometer.hardware.pollsters.disk:DiskTotalPollster
hardware.disk.size.used = ceilometer.hardware.pollsters.disk:DiskUsedPollster
hardware.memory.swap.avail = ceilometer.hardware.pollsters.memory:MemorySwapAvailPollster
hardware.memory.swap.total = ceilometer.hardware.pollsters.memory:MemorySwapTotalPollster

[ceilometer.hardware.inspectors]
snmp = ceilometer.hardware.inspector.snmp:SNMPInspector

Thirdly, check if any error in the ceilometer related logs , normally it might be the keystone authentication issue, if that is the case, check the configuration in ceilometer.conf for [keystone_authtoken].

Finally, make sure your meter_sink does not filter out the hardware meterics, you can use "*" for all metrics like this

...
 - name: meter_sink
          meter: "*"
          transformers:
          publishers:
              - notifier://?per_meter_topic=1
...

Note that: there is a major change in the juno release in code structure, the above solution is based on icehouse version. Hope that helps!

Vic