SNMP (Problems?) w/The Dude

RouterOS The Dude
1

I’m troubleshooting an SNMP issue with respect to monitoring switches with the Dude. It seems that the switches I’m monitoring (5 Netgear FSM726s) stop responding to SNMP queries every minute or so.

The result is that The Dude is constantly adding and removing snmp data to and from the switches–very frustrating when mapping and monitoring links. At first I thought that there was a software issue with the switches. However, if I disable SNMP on the Dude, the devices start responding to snmpwalks from local systems within 30 seconds.

However, the snmpwalk on these switches takes upwards of 60-120 seconds to dump all of the data (they aren’t that slow–theres just a TON of it it seems). I believe what is happening is The Dude is running an snmpwalk of the devices, which begins running, but is only partially complete by the time The Dude starts another snmpwalk. This snowballs until the switch can no longer handle any more concurrent snmpqueries, causing The Dude to start timing out snmp data that was discovered in the previous snmp queries.

First, is my hypothesis correct? If so, is there any way I can prevent this from happening with the current Dude version?

Thanks in advance.

Andrew

2

Why would the Dude be SNMP walking your switches all the time? The Dude will only request specific SNMP OID’s from your devices (only those you’ve told The Dude to monitor). Probably cpu, mem, some link stats, that sort of thing, plus specific SNMP queries you yourself might have created. None of these would cause a SNMP walk.

No?

3

I imagine that The Dude runs periodic snmpwalks of devices in order to discover new OIDs, etc. How else would the SNMP tab be populated with new data periodically? It appears that multiple snmpwalks are executed concurrently if the first one doesn’t finish in time.

4

I would assume the SNMP tab is populated simply by querying for some specific OID’s (or arrays of OID’s). All in all The Dude might request some tens of OID’s (perhaps a few hundred) every 20 seconds or so. Should not be any problem.

In the end: I do not know the inner workings of The Dude. But populating the SNMP tab would certainly not require a full SNMP walk (A single full SNMP walk could indeed take minutes to complete, so that’s certainly not something you want happening every 20 seconds :smiley: )