I`m a little bit confuse about how PRTG choose "Interface number" while creating SNMP Traffic Sensor Manualy or running Auto Discovery on specific host. Let me explain what i mean. While creating SNMP Traffic Sensor in a first time PRTG sets it`s "Interface number" (it can be see at Settings tab of a sensor) to something like "1","2","3" etc. according to device interface number. That`s fine to me. But. As soon as i create or change device interface description (like "my_favorite_server") and then start auto discovery process for this device, PRTG creates a copy of existing SNMP Traffic Sensor for this interface giving it`s "Interface number" value like "1:my_favorite_server".

So, for every SNMP Traffic Sensor with changed device interface description, PRTG creates another one sensor with "new" "Interface number". Frequent change of device interface description will result in constant loss of historical data or hundred of copied sensors.

Questions are: 1. Why PRTG uses device interface description while setting Interface number. 2. Can i choose somehow or somewhere naming policy (tell PRGT use only device interface number w/o adding it`s description).

P.S. Monitored devices: DLink DES-3526 / DES-3550 / DES-3200 / DGS-3700-12G Cisco Catalyst 3750 Cisco 7301 / Cisco 2851

Article Comments

Hello,

where do you change the interface descriptions? On the switches/routers? As soon as PRTG finds a new combination of Interface number and Sensor Name it will create a new sensor (using the Auto-Discovery), as we consider this a new sensor. Which does not mean, other opinions are wrong of course), we just don't want PRTG to rename sensors itself "automatically" (when a sensor name has changed on an interface number, for which PRTG already has a sensor for), without our users awareness.
You can change the name-template according to which PRTG names the SNMP Traffic Sensors in "SNMP Compatibility Options" of the "Settings"-tab of the device (or higher on group level).

Best Regards.


Jan, 2011 - Permalink

Hello again. I change interface description right on the switch (by example, command may look like "config ports 25 description MyFavoriteServer"). After that next Auto-Discovery process creates new sensor with new combination "interface-number:description". We are compelled to change descriptions often enough and in our case such PRTG "logic" is very "uncomfortable". Ideally we would like to see automaticaly changing sensors names due to changes in interfaces descriptions and may be recieve some kind of notify about that like the way Auto-Discovery creates new "ToDo". But, correct me if i wrong, such possibility is absent in current version of PRTG Network Monitor.

Other question is why PRTG continue making graph of "old" sensor despite that "new" sensor with new combination of interface number and it`s description was created?

ps. would you be so kind and explain the logic of Auto-Discovery process while addng new SNMP Traffic Sensors. How Auto-Discovery determine that sensor must be created for this interface? Does it simply check connected or not? Does it consider some kind of SNMP traffic counters (traffic counters for this specific interface equal zero or more that zero)? Asssume that i have some interfaces that change it`s states (from down to up) for some small period of time (1-2 hours in a day) and Auto-Discovery process runs one time per day. Would Auto-Discovery "catch" that interface and create sensor? Or i will never have sensors for that interfaces?


Jan, 2011 - Permalink

The Auto-Discovery checks if the traffic counter for an interface is higher than '0', if that is the case, and there isn't a sensors existing already with the same combination of interface number and name, then it will create a new sensor. We plan to implement a function to have PRTG update sensors names, but there is no ETA set for this yet. Please bear with us.


Jan, 2011 - Permalink