Why does Netreo sometimes show over 100 percent utilization on some interfaces?
- 09 Sep 2024
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Why does Netreo sometimes show over 100 percent utilization on some interfaces?
- Updated on 09 Sep 2024
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Netreo detects interface bandwidth speed using SNMP. Specifically, it reads the ifSpeed and ifHighSpeed MIBs.
First, Netreo checks the ifSpeed MIB. If it responds with a proper speed value, then that value is reported in the user interface. If it responds with 0 or 4294967295, then Netreo checks the ifHighSpeed MIB for a speed value. Netreo does not check the ifHighSpeed MIB unless the ifSpeed MIB reports one of those two values.
SNMP version and supported MIBs
Use of the ifHighSpeed MIB is only supported when using SNMPv2c or SNMPv3 to poll a managed device. If a device is set to use any other version for polling, only the ifSpeed MIB is used (regardless of whether or not ifHighSpeed OIDs respond). See Device Template and Device Administration for information on setting the polling method for managed devices.
Note that the ifHighSpeed MIB reports only in megabits (not fractions). Therefore, to avoid rounding off the bandwidth on low-speed ports, all interfaces with a reported speed below 1 Gbps (1,000,000,000 bits/second) use the ifSpeed MIB exclusively.
Cisco Bandwidth Errors
The bandwidth we detect on Cisco devices is determined by what you set with the Bandwidth command on that interface. If it is not set or set incorrectly, the numbers, percentages, and thresholds in Netreo may be incorrect.
Serial Interfaces
If Netreo detects that an interface is a serial interface, it allows for a certain amount of bursting over 100%. However, this doesn’t change the “maximum” used to calculate percentages – that is always strictly based on the bandwidth setting.
If the interface is more than 56 Kbps but less than 1.5 Mbps, it assumes it could burst as high as 1.5 Mbps.
If the interface is over 1.5 Mbps but less than 45 Mbps, it assumes it might be a fractional T3 and allows bursts up to 45 Mbps.
If the interface is more than 45 Mbps but less than 155 Mbps, it assumes it might be a fractional OC3 and allows bursts up to 155 Mbps.
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