Interface Utilization missing from performance tab for VPN.

Products

• Network Observability
• Spectrum

Issue/Introduction

Fortigate firewalls have VPNs configured under the loopback interface but none show Interface Utilization in the performance tab.  The VPNs were configured on the device.

Cause

IfSpeed and IfHighSpeed are both showing as zero in the devices mibs for these interfaces so we are unable to make the bandwidth utilization calculation.  We can only show the information the mib gives us and if this is incorrect, then we will show the same in Spectrum.

We pulled this info from the ifTable in mib tools. 

Resolution

Please discuss with the firewall vendor to understand why this is not populated correctly.

Additional Information

To calculate the performance graph of the interface, Spectrum uses the following components, which are polled from the device's MIB:

Octet Counters: The system polls the change in octet (byte) counters over a specific time interval. It will use 64-bit high-capacity counters if the device supports them. 

ifOutOctets   "The total number of octets transmitted out of the interface, including framing characters."    ::= { ifEntry 16 } --1.3.6.1.2.1.2.2.1.16
 
ifInOctets "The total number of octets received on the interface, including framing characters."    ::= { ifEntry 10 }-- 1.3.6.1.2.1.2.2.1.10
Interface Speed (Bandwidth): The calculation also requires the interface's maximum speed or bandwidth. This value is read from one of two MIB OIDs:

ifSpeed: 1.3.6.1.2.1.2.2.1.5 (for lower-speed interfaces)
ifHighSpeed: 1.3.6.1.2.1.31.1.1.1.15 (for higher-speed interfaces, measured in units of 1,000,000 bits per second)
If they exist on the device in the mibs we can show them in the console.

This problem may be a known issue e.g. 

https://docs.fortinet.com/document/fortigate/7.4.7/fortios-release-notes/236526/known-issues

1145907  Bandwidth widget does not report the traffic correctly for backup VLAN interfaces.