I have several 6500 Sup720s running IOS 12.2(18)FX7.
'MLS QOS' is configed globally and 'mls qos trust dscp' is on all the interfaces. Other than that everything else is default as far as MLS qos is concerned. I've enabled MLS QOS so the switches will trust the dscp markings on voice packets and to also set up the appropriate priority queue for the voice packets traveling through the switches.
Now I'm trying to learn what all the counters mean and have a question about one of them. Here is the output of 'show mls qos':
ROC-6504-DW-A#sh mls qos
QoS is enabled globally
Policy marking depends on port_trust
QoS ip packet dscp rewrite enabled globally
Input mode for GRE Tunnel is Pipe mode
Input mode for MPLS is Pipe mode
QoS Trust state is DSCP on the following interface
Gi2/1 Gi2/2 Gi2/3 Gi2/4 Gi2/5 Gi2/6 Gi2/7 Gi2/8 Gi2/9 Gi2/10
Gi2/11 Gi2/12 Gi2/13 Gi2/14 Gi2/15 Gi2/16 Gi2/17 Gi2/18 Gi2/19 Gi2/20
Gi2/21 Gi2/22 Gi2/23 Gi2/24 Gi4/1 Gi4/2 Gi4/3 Gi4/4 Gi4/5 Gi4/6
Gi4/7 Gi4/8 Gi4/9 Gi4/10 Gi4/11 Gi4/12 Gi4/13 Gi4/14 Gi4/15 Gi4/16
Gi4/17 Gi4/18 Gi4/19 Gi4/20 Gi4/21 Gi4/22 Gi4/23 Gi4/24 Gi4/25 Gi4/26
Gi4/27 Gi4/28 Gi4/29 Gi4/30 Gi4/31 Gi4/32 Gi4/33 Gi4/34 Gi4/35 Gi4/36
Gi4/37 Gi4/38 Gi4/39 Gi4/40 Gi4/41 Gi4/42 Gi4/43 Gi4/44 Gi4/45 Gi4/46
Gi4/47 Gi4/48
Vlan or Portchannel(Multi-Earl) policies supported: Yes
Egress policies supported: Yes
----- Module [1] -----
QoS global counters:
Total packets: 406108
IP shortcut packets: 0
Packets dropped by policing: 0
IP packets with TOS changed by policing: 0
IP packets with COS changed by policing: 23055
Non-IP packets with COS changed by policing: 0
MPLS packets with EXP changed by policing: 0
What does the line:
'IP packets with COS changed by policing: 23055'
...mean?
Is there some default policing going on and how do I find out what packets' COS values are being changed?
I want this switch to trust the dscp markings that go through it and need to make sure that this counter isn't telling me that some voice or call control packets markings are being changed.
