Using SNMP to monitor LTM traffic

Hello ,everyone! im Jepson, i want to use SNMP to monitor BIGIP LTM. there are two LTM 1600 in my company , and i have done a HA between them. now i want to monitor the ISP traffic , so i think i need to monitor the ifInOctets and ifOutOctets of export ports on the twoLTMs,when i snmpwalked them ,it worked ,and i could get their results,but when i used zabbixto monitor these parameters, the graphs showed the traffic was just 100+ bps, and i also tested other kind of devices, it produced normal traffic graphs with mbps traffic

so,can anyone tell me why the export ports of LTM return just 100+ bps traffic, did i monitor the wrong port ,or i need to monitor the LTM export vlan ?