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Cisco Bug: CSCvu72792 - Only 123 and 124 bytes IPv4 frames hit tail drops in wire rate testing in NCS5500 36x100GE LC(7.0.2)

Last Modified

Aug 12, 2020

Products (1)

  • Cisco Network Convergence System 5500 Series

Known Affected Releases

7.0.2

Description (partial)

Symptom:
In specific test cases for NCS5500 with 36x100GE wire rate traffic for QoS (CBWFQ). in 7.0.2

123byte and 124 byte (with IPv4 Tos0 - 7) traffic flow with 12.5% each in bi-directional wire rate, only Tos=0 traffic drops.

Also, 122byte and 123 byte Label (with EXP=0 - 7) traffic flow with 12.5% each in bi-directional wire rate, only EXP=0 traffic drops.

In other cases, there is no traffic loss.(say, Only Tos=0 100% traffic, no loss found)

Conditions:
Brief diagram: Bi-directional wire rate traffic flow;

                     +------------+
HundredGigE0/0/0/27  |            |   HundredGigE0/0/0/19
IXIA <---------------+     UUT    +------------> IXIA
                     |            | 
                     +------------+

123byte and 124 byte (with IPv4 Tos0 - 7) traffic flow with 12.5% each in bi-directional wire rate, only Tos=0 traffic drops.

Also, 122byte and 123 byte Label (with EXP=0 - 7) traffic flow with 12.5% each in bi-directional wire rate, only EXP=0 traffic drops.

In other cases, there is no traffic loss.(say, Only Tos=0 100% traffic, no loss found)
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