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Cisco Bug: CSCvi70692 - QOS marking not working due to action string character limit

Last Modified

Jul 30, 2018

Products (1)

  • Cisco ASR 1000 Series Aggregation Services Routers

Known Affected Releases

15.4(3)S5.1

Description (partial)

Symptom:
QOS marking not working as expected, we see the packets correctly matched under the class but the the set operation is not working. 


Conditions:
Issue is seen when we have long and identical names for the policy map and class-map. The issue here happens due to duplicate set-ids being sent to qos-pd. The set-id for an action is generated by hashing the string for the policy-name, class-name & action-string combination to an integer value (referred as config-index). The max-length of the action-string (policy-name+class-name+action) for the hash-function to compute a config-index for an action is 80 characters

Sample Policy : 

policy-map TenGigabitEthernet0/0/0.1000-QOS_TEST-EXP
 class TenGigabitEthernet0/0/0.1000-QOS_ACL1-CLASS-A
   set mpls experimental imposition 3
    service-policy QOS_TEST-GRE
 class TenGigabitEthernet0/0/0.1000-QOS_ACL1-CLASS-B
   set mpls experimental imposition 2
    service-policy QOS_TEST-GRE
 class TenGigabitEthernet0/0/0.1000-QOS_ACL1-CLASS-C
   set mpls experimental imposition 1
    service-policy QOS_TEST-GRE
 class TenGigabitEthernet0/0/0.1000-QOS_ACL1-CLASS-D
   set mpls experimental imposition 0
    service-policy QOS_TEST-GRE
 class class-default
   set mpls experimental imposition 2
    service-policy QOS_TEST-GRE


The action-string being used to generate config-indexes becomes effectively the same for all user-defined classes of the policy : TenGigabitEthernet0/0/0.1000-QOS_TEST-EXP TenGigabitEthernet0/0/0.1000-QOS_ACL1

Verification :

sh platform hardware qfp active feature qos psqd input interface TenGigabitEthernet0/0/0.1000 : 

            Class index: 0, Class object id: 2031425, Match index: 0
            Class name: TenGigabitEthernet0/0/0.1000-QOS_ACL1-CLASS-A, Policy name: TenGigabitEthernet0/0/0.1000-QOS_TEST-EXP
psqd[0-3]: 0x00000000 0x00000000 0x00000000 0x00000000
 

The above value should be : 
      psqd[0-3]: 0x00000300 0x00000020 0x00000000 0x00000000  --> 03 is for exp 3, 0x20 is "set mpls exp'
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