An SNMP sensor setup against a Cisco router sub-interface returns no data, even though there is data traversing that interface. I believe this is because the sub-interface is configured as the dot1q native VLAN.

Does anyone know whether this is a bug/know problem with PRTG and whether it has been fixed in a more recent version?

Details: interface Ethernet0

interface Ethernet0.200000 description SNMP Sensor 1 - No Data encapsulation dot1Q 200 native

interface Ethernet0.200201 description SNMP Sensor 2 Shows Data Correctly encapsulation dot1Q 201

interface Ethernet0.200202 description SNMP Sensor 3 Shows Data Correctly encapsulation dot1Q 202

I am using PRTG version 8.4.2.2321

Article Comments

Simon, have you found a resolution to this problem? I'm having the same type of issue montitoring Layer 2 802.1q Virtual LAN interfaces with a SonicWALL e5500 firewall. SNMP shows "ok", but no traffic stats at all. I posted a reply to a similar post from another Sonicwall user, but no replies yet.


Nov, 2011 - Permalink

I have the same Problem with sub-interfaces in PRTG.


Feb, 2013 - Permalink

we will have a SonicWall in our test lab soon so that we can take a look at the issue


Feb, 2013 - Permalink

We are still having this issue on our cisco C2951 router.

You can select the interfaces in the adding sensor phase but then all the sensors once added say no such interface.

Has there been any resolution on this?


Jul, 2014 - Permalink

We were able to create a VLAN on our Sonicwall here and were able to create a sensor in PRTG for the Sub-interface and the sensor was able to show the correct amount of traffic that was travelling through the VLAN. If you are still having issues with this, please write us an email to support@paessler.com and we can work on this together. Please mention this KB article as well so we can reference the case and post the solution.


Aug, 2014 - Permalink