SNMP discovery does not find any devices

Problem

You launched an SNMP discovery run but didn't find all of the expected devices.

Solution

The SNMP discovery process will run against every IP address in your list from the cidrs section in the discovery configuration. During the scan, there's a TCP port check to ensure the target IP address is responsive. If successful, ktranslate will then attempt to communicate with the IP address via SNMP.

Common failure points in the discovery process include:

• Timeouts due to either network latency or device response times to SNMP requests. Meraki Cloud Controllers recommend at least a 10s timeout value, for instance.
• Initial failures on the responsiveness check from devices that are generally under tighter security postures, like firewalls.
• Timeouts due to excessively large IP range presented in the cidrs section of the discovery configuration.

1,024 IPs / 4 threads = 256 IPs per thread 
256 IPs per thread * 3 seconds per IP = 768 seconds
768 seconds / 60 = 12.8 minutes

To work around these problems, try one or all of the following solutions:

1. Edit the snmp-base.yaml and increase the timeout value for the timeout_ms variable.
2. For devices that still seem unresponsive, set all the cidrs values to a length of /32, which forces the discovery process to skip the responsiveness check and only attempts the SNMP connection.
3. If you are receiving timeouts on the entire job, ensure that you're limiting the provided CIDR blocks to 1,024 or less total IPs. For example, a CIDR range between /22 and /32. You can provide multiple blocks of /22 in a single configuration file, but overall we recommend you to horizontally scale into multiple containers when you have large target environment versus trying to do all of the work in a single container.