SNMP issue...

[lambert]

Hello..
Im graphing with mrtg some routers and some CPE, a couple of days ago, snmp stopped working on 3 routers, so i tought it was a routing issue since i was changing some stuff, but both devices, the mrtg server and the router are able to ssh, ping, etc.. just snmp does not work, even if i try connected directly to the router and i nmap udp port 161, it says, open/filtered.

Is the path from the server to the router the same as the path from the router to the server?

There is a long standing issue with SNMP on RouterOS not replying from the IP to which the request was addressed when the reply packet leaves the router via a different interface with a different IP address.

http://forum.mikrotik.com/t/snmp-doesnt-work-with-asymmetric-routes/58545/1

In 6.40 and later, we now have the ability to specify the src-address for SNMP traffic. That should help with this issue.