difference between Cisco "cbQosClassMapStats" and "cbQosPoliceStats" SNMP objects

Question

I have a Cisco ASR-9001 router running IOS-XR version 4.2.3 and its interface Gi0/0/0/5.1 has following service-policy applied in ingress direction:

!
policy-map bw-cir-50Mbps
 class class-default
  police rate 50 mbps burst 937500 bytes 
   exceed-action drop
  !
 !
 end-policy-map
!

Now if I execute the sh policy-map interface Gi0/0/0/5.1 input command I can see that that the policer has dropped 26472 packets and 37176528 bytes:

RP/0/RSP0/CPU0:r1#sh policy-map interface Gi0/0/0/5.1 input | i dropped
    Policed and dropped :               26472/37176528           
RP/0/RSP0/CPU0:r1#

Now if I search through the whole SNMP OID tree of SNMP agent in r1 router, I receive following results:

$ snmpwalk -v 2c -c public r1 iso | grep -E "26472|37176528"
CISCO-SMI::ciscoMgmt.166.1.15.1.1.13.1846028775.1748208914 = Counter32: 26472
CISCO-SMI::ciscoMgmt.166.1.15.1.1.14.1846028775.1748208914 = Counter64: 26472
CISCO-SMI::ciscoMgmt.166.1.15.1.1.16.1846028775.1748208914 = Counter32: 37176528
CISCO-SMI::ciscoMgmt.166.1.15.1.1.17.1846028775.1748208914 = Counter64: 37176528
CISCO-SMI::ciscoMgmt.166.1.17.1.1.9.1846028775.1163943827 = Counter32: 26472
CISCO-SMI::ciscoMgmt.166.1.17.1.1.10.1846028775.1163943827 = Counter64: 26472
CISCO-SMI::ciscoMgmt.166.1.17.1.1.12.1846028775.1163943827 = Counter32: 37176528
CISCO-SMI::ciscoMgmt.166.1.17.1.1.13.1846028775.1163943827 = Counter64: 37176528
$

As seen above, there are two "sections", i.e. CISCO-SMI::ciscoMgmt.166.1.15(cbQosClassMapStats) and CISCO-SMI::ciscoMgmt.166.1.17(cbQosPoliceStats). What is the difference between the two? Under which circumstances cbQosClassMapStats differs from cbQosPoliceStats?

Answer 1

Class-maps can be used for much more than just policing traffic.

The more general "cbQOSClassMapStats" would show a different count if you were also taking other actions than just "police".

For example, if in the same class map you were also queueing, you'd need to look at the "cbQOSQueueingStats" OID.

I'd recommend reading through Cisco's MIB object navigator for CISCO-CLASS-BASED-QOS-MIB for more information.