Message: "No response to SNMP"

Document ID : KB000023642
Last Modified Date : 14/02/2018
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Issue: 

Polling error: No response
Receiving no response to SNMP message during polling
Polling error generated: Error: "No response to SNMP"

Environment:  

eHealth

Cause: 

The most common cause of "No response to SNMP" errors during a polling cycle is due to an eHealth timeout waiting for the polled device to respond to the SNMP request.

Resolution:

Increasing the value of the NH_SNMP_TIMEOUT environment variable will allow eHealth to wait longer for device responses.

The default value for the NH_SNMP_TIMEOUT variable is equal to 4000000 microseconds (4 seconds). 

Alternately the value of the NH_SNMP_RETRIES environment variable could be increased. This variable controls how many times Network Health will send an SNMP request to a device.

The default value for the NH_SNMP_RETRIES variable is 3. 

NOTE: Each time eHealth resends an SNMP request to a device the timeout period is, by default, doubled. 

Example: 
        NH_SNMP_TIMEOUT set to 4000000
        NH_SNMP_RETRIES set to 5 

In the above example, an SNMP request is sent to a network device that does not respond. The first time the device is queried eHealth will wait 2 seconds before sending another query. On the second query eHealth will wait 4 seconds. The third query will wait 8 seconds. The fourth 16 seconds, and the fifth will wait 32 seconds. 

This means if this device fails to respond the total time elapsed form the first attempt through all of the retries would be 2+4+8+16+32 = 62 seconds. 

Increasing this variable can have a dramatic effect on the overall poll cycle time and should only be modified incrementally to limit this affect.

Additional Information:

Refer to How to Set or Change eHealth Environment Variables-Unix or How to Set or Change eHealth Environment Variables-NT for more information.

Also verify network connectivity and check any firewall and access control list issues on the device itself.