I have previously read that the 'show policy-map interface x/x' when used on Catalyst 3550 & 3750 switches does not actually show any counters - it shows the policy that is attached but all counters are zero. If you want to see counters for QoS service-policies you need to use the command 'show mls qos interface statistics'. The reason for this is there is no NetFlow hardware (?) in the switches to record these statistics. You need at least a Catalyst 4500 SupIV with the NFFC module.

That was my understanding. Anyway today I was looking at some Catalyst 3550's running IP Services that were using routed (non-SVI) interfaces. I created some service policies that were for 'policy adherance' - i.e. the classification was being performed at an access layer switch that then connected to the 3550 via a Layer-3 link. On the ingress interface of the 3550 we applied a policy to trust various DSCP values and mark them down if they exceeded the agreed rates (policy adherance?):

mls qos map policed-dscp 0 18 24 34 46 to 8

!

policy-map Ingress-Check-Policy-100Mbps

class Trusted-EF

police 30000000 8000 exceed-action policed-dscp-transmit

trust dscp

class Trusted-CS3

police 2000000 8000 exceed-action policed-dscp-transmit

trust dscp

class Trusted-AF41

police 10000000 8000 exceed-action policed-dscp-transmit

trust dscp

class Trusted-AF21

police 33000000 8000 exceed-action policed-dscp-transmit

trust dscp

class Best-Effort

police 25000000 8000 exceed-action policed-dscp-transmit

set ip dscp default

!

interface FastEthernet0/1

no switchport

ip address 10.1.1.1 255.255.255.252

service-policy input Ingress-Check-Policy

!

When I issue the 'show policy-map interface FastEthernet0/1' I actually get counters and they are consistent with the 'show mls qos interface statistics' command. I played around with this a bit more and if I change the exceed action to 'drop' and drops are happening they are not reported by the 'show policy-map interface' command, however they are with the 'show mls qos...' command.

I attempted the same configuration on a 3750 but no counters were displayed for the 'show policy-map interface' command at all.

Does this sound correct? Is this a 'quirk' with the 3550? The 3560/3750 is looking more and more like a backward step when comparing it to the 3550 :o(

Andy