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Cisco Bug: CSCum99180 - Latency in PQ gets high under a certain traffic condition

Last Modified

Apr 17, 2019

Products (1)

  • Cisco ASR 1000 Series Aggregation Services Routers

Known Affected Releases

15.3(3)S 15.4(1)S

Description (partial)

Symptom:
Latency in PQ gets high under a certain traffic condition

Conditions:
In the QoS scenario bellow, latency in PQ gets high in specific situation.

This issue happens when specifically shape rates <= 1Mbps

####Example for conditions####
The interface is shaped as to 1Mbps with  "account user-defined 24" in PARENT policy.
CHILD policy has 2 classes which is configured with  "priority percent", another is configured with "bandwidth remaining"

Here is configured priority percent and the rate of test traffic in each scenario.

Two streams with different rate and frame size( Both are classified into PQ)
The Maximum Latency is greater than 1100μs.

class-pq:89% (890 kbps).
DSCP       pps            byte         Maximum Latency(μs)
CS6         409             85                    1100
             12             64                    1133
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