With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
csqModuleCosChangedPackets
Cisco Switch QOS Module Cos Changed Packets
1.3.6.1.4.1.9.9.580.1.5.3.1.45
The number of packets (IP and non-IP) that have the CoS value changed due to policing.
Back to CISCO-SWITCH-QOS-MIB MIB page.
IPHost Network monitor allows you to monitor csqModuleCosChangedPackets 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.
