With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
csiNportInBytesRate
csi Nport In Bytes Rate
1.3.6.1.4.1.9.9.378.1.1.4.1.5
Number of incoming bytes per second on this virtual N-port.
Back to CISCO-SVC-INTERFACE-MIB MIB page.
IPHost Network monitor allows you to monitor csiNportInBytesRate on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco firewalls right now.