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Policy-map counters not increasing for QOS

rick505d3
Beginner
Beginner

Hi,

I am doing a lab test to verify QOS on a Cisco 2960s 49P switch. The service policy applied to the interface Gi1/0/1 seems to be working as Wireshark capture (on the uplink trunk ports) indicate all traffic is correctly marked ("ef" for testint purposes). However, none of the counters in "show policy-map int gi1/0/1" seems to be increasing.

Standard IP access list acl-01

    10 permit any

Class Map match-all cm-01 (id 4)

   Match access-group name acl-01

 

  Policy Map pm-01

    Class cm-01

      set dscp ef

 

interface GigabitEthernet1/0/1

switchport access vlan 240

switchport mode access

switchport voice vlan 234

spanning-tree portfast

service-policy input pm-01

 

#show policy-map  interface gi1/0/1

GigabitEthernet1/0/1

  Service-policy input: pm-01

    Class-map: cm-01 (match-all)

      0 packets, 0 bytes

      5 minute offered rate 0 bps, drop rate 0 bps

      Match: access-group name acl-01

    Class-map: class-default (match-any)

      0 packets, 0 bytes

      5 minute offered rate 0 bps, drop rate 0 bps

      Match: any

        0 packets, 0 bytes

        5 minute rate 0 bps

#show mls qos

QoS is enabled

QoS ip packet dscp rewrite is enabled

#show mls qos  interface gi1/0/1

GigabitEthernet1/0/1

Attached policy-map for Ingress: pm-01

trust state: not trusted

trust mode: not trusted

trust enabled flag: ena

COS override: dis

default COS: 0

DSCP Mutation Map: Default DSCP Mutation Map

Trust device: none

qos mode: port-based

#show ver

Switch Ports Model              SW Version            SW Image

------ ----- -----              ----------            ----------

*    1 52    WS-C2960S-48LPS-L  15.0(2)SE2            C2960S-UNIVERSALK9-M

Has anyone else observed this ? A bug ?

Regards,

Rick.

1 Accepted Solution

Accepted Solutions

Peter Paluch
Hall of Fame Cisco Employee Hall of Fame Cisco Employee
Hall of Fame Cisco Employee

Hi Rick,

I believe this is normal behavior. On switches, many operations including QoS marking manipulation is performed in hardware while the show policy-map command shows you the software counters associated with the policy-map. As the hardware does not report back the number of packets handled by the policy-map (which could be quite intensive as these operations are performed at wire rate), the counters in the policy-map are not incremented. The same goes, for example, for ACLs - the counters displayed by individual ACL entries do not increase, either.

If you check out the command reference for this command at:

http://www.cisco.com/en/US/docs/switches/lan/catalyst2960/software/release/15.0_2_se/command/reference/cli2.html#wp1948343

the documentation says: Though visible in the command-line help string, the control-plane and interface keywords are not supported, and the statistics shown in the display should be ignored.

Best regards,

Peter

View solution in original post

2 Replies 2

Peter Paluch
Hall of Fame Cisco Employee Hall of Fame Cisco Employee
Hall of Fame Cisco Employee

Hi Rick,

I believe this is normal behavior. On switches, many operations including QoS marking manipulation is performed in hardware while the show policy-map command shows you the software counters associated with the policy-map. As the hardware does not report back the number of packets handled by the policy-map (which could be quite intensive as these operations are performed at wire rate), the counters in the policy-map are not incremented. The same goes, for example, for ACLs - the counters displayed by individual ACL entries do not increase, either.

If you check out the command reference for this command at:

http://www.cisco.com/en/US/docs/switches/lan/catalyst2960/software/release/15.0_2_se/command/reference/cli2.html#wp1948343

the documentation says: Though visible in the command-line help string, the control-plane and interface keywords are not supported, and the statistics shown in the display should be ignored.

Best regards,

Peter

Thanks Peter. That explains the behaviour.

Regards,

Rick.

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