snmpwalk timeouts

RouterOS General
1

I’ve noticed The Dude having trouble getting cpu and interface usage figures for my primary router from time to time. I ran some test snmpwalk commands and found they all time out at various points in the walk. If I rerun the snmpwalk immediately after the timeout, it too times out with no data returned. A packet trace run on the router shows the snmp requests and answers flowing up until the timeout. At this point the snmpwalk sends a request every second for 5 second but no reply packets are generated by the router.

Watching the snmp tab for the router in the dude, I see the interface and other entries disappear from time to time and then pop back in.

My router is a Dell server runninf RouterOS 4.5. I am running BGP and peered with many other ISPs so my routing table currently has 17363 entries. This may well be causing the snmpwalk to return quite a lot of data.

Nothing shows up in the router log when I turn on debug logging and there isn’t a log option for SNMP.

The router CPU utilization (as seen from the Winbox system – resources panel) is sitting at around 5% so the router isn’t exaclty stressed.

I can’t see any SNMP fixes in the change logs for later releases.

Any suggestions?

SNMP issues with BGP router
2

There could be issues running SNMPwalk on BGP router, it is not recommend to run SNMP queries on BGP router.
When there are too many routes, you can experience timeout and there could be situation that SNMP will not be able to get all routers, when new routes will be already present.

3

When you say that it isn’t recommended to run SNMP queries on a BGP router, do you mean that I shouldn’t try to get any SNMP information from the router at all or just not run something large like the snmpwalk?

I can try to tailor my monitoring to just use a few choice OIDs I suppose. At present the monitor is The Dude and it looks like The Dude scans the router in it’s entirety when SNMP is enabled for teh device definition.

4

Yes, it would be much better not to monitor entire route table, but just specific OID that you need from the router.

5

Is there a way to stop RouterOS responding to SNMP requests for the routing table? In The Dude fourm gsandul supplied the link http://www.cisco.com/en/US/tech/tk648/tk362/technologies_tech_note09186a00800948e6.shtml to show how to turn off routing responses for Cisco. Is there anything similar for RouterOS?