This article applies as of PRTG 23
In PRTG, SNMP Traffic sensors for an Extreme Switch are not showing traffic above 610 Mbps, even though the actual traffic is not decreasing which persists in both PRTG versions 8 and 14 using SNMP version 2.
Querying 64-bit counters with SNMP Traffic sensors
Hello, thank you for your inquiry.
You are most likely using an SNMP Traffic sensor or SNMP Traffic v2 sensor that queries 32-bit counters for a Gigabit interface.
According to Cisco, 32-bit SNMP counters will stop working at around 650,000,000 bits/second. 'Stop working' means that the data is no longer reliable as the counter is constantly overflowing. This can lead to the situation that you are experiencing.
The most recent devices and SNMP implementations support 64-bit counters that can hold much larger values and will not display this behavior of overflowing. PRTG uses the 64-bit counters whenever possible, as long as the following requirements are met:
- The SNMP version must be v2c or v3. SNMP v1 does not support 64-bit counters.
- The device's SNMP Compatibility Settings must be configured to Use 64-bit counters if available (recommended). This is the default setting.
- The device must provide 64-bit counters. You can confirm their existence by doing a Walk of 1.3.6.1.2.1.31.1.1.1.6 with SNMP Tester.
When switching from 32-bit to 64-bit counters, you must recreate the SNMP Traffic and SNMP Traffic v2sensors, as PRTG only checks for available counters at sensor creation. You can identify the type of your sensor under Sensor Type on the sensor's Overview tab.
The screenshot below shows a 32-bit SNMP Traffic sensor:
Disclaimer:
The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.
