I have a problem to use SNMP on some of my Dell M1000e CMCs. They should be all configured the same, but some don't respond to a simple snmpwalk attempt:
# snmpwalk -v 2c -c public mc-jux9
Timeout: No Response from mc-jux9
A colleague of mine suspected a connection with the latest CMC firmware update, but some machines running CMC 5.0 work fine while others don't.
Have you checked the settings of the CMCs? Make sure SNMP is enabled, community is public, and DNS name is working properly. Try with the IP address instead of mc-jux9.
yes, SNMP is properly enabled on the CMC, the community string is public and DNS is fine. I've also checked with the IP, same effect.
I'm just receiving not a single byte of answer from the CMC.
Are you able to ping the CMC IP address from the system you are testing SNMP from? Is there anything different about the CMCs that are not responding to SNMP such as location, connected to a different switch, on a different VLAN or subnet, etc? Is the system you are testing SNMP from on the same local network? Have you tried failing over the CMCs?
Ping to the CMC is fine. The blade chassis are all connected to the same switch, there are two subnets, but of those that work and that don't work are several in the same subnet. The system I'm testing from is on a different network (public instead of private), but the routing should work according to my network experts. I have tried failover, no avail.
You need to limit the factors involved. Test from a local system on the same switch instead of a computer over the internet. If you can't install an SNMP monitor or test on one of the other blades then test from something that is at least on the local network.
The most likely issue is going to be a network/firewall/security problem. I have checked and there are no issues we are aware of with the 5.0 firmware that would stop SNMP from functioning. The first step is to verify that it is configured correctly, you said that it is. The next step is to limit or bypass as much of your network infrastructure as possible to rule out a network or security issue.
I have downgraded the CMC firmware to 4.5 and the SNMP check works again. Another upgrade to 5.0 and SNMP doesn't work anymore. I've contacted the Dell Pro support, let's see if they will be able to help.
The Dell support found a workaround: I had the character '/' in the field 'Chassis Location', this made the SNMP server on the CMC fail. I have removed the character and SNMP started working.