Most of the third party sflow applications display incorrect interface statistics based on sflow information received. This is because interface index reported by a FortiGate in sflow packets is different to the ifIndex value of the port numbers.

The application assumes that the sflow source index reported should match the SNMP ifIndex value, will poll the FortiGate, if configured, for additional SNMP information such as ifDescription, ifSpeed, ifInOctets, ifOutOctets, and will then associate these flows with a wrong interface.

Therefore, the mapping should be configured on the sflow analyzer.