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Cisco Bug: CSCvv98385 - Nexus 9000 "Fabric Port Class X Output Drop Packets" counter constantly incrementing

Last Modified

Oct 06, 2020

Products (1)

  • Cisco Nexus 9000 Series Switches

Known Affected Releases

7.0(3)I7(9) 9.3(5)

Description (partial)

Symptom:
A Nexus 9000 Series switch equpped with a Cloud Scale ASIC may have one or more large non-zero "Fabric Port Class X Output Drop Packets" counters in the output of `show hardware internal errors all`. An example of this output is shown below.

switch# show hardware internal errors all 
<snip>
ID    Name                                          Value             Ports
--    ----                                          -----             -----
6029314 Fabric Port Class 6 Output Drop Packets       0000000000000016  1,9,17 - 
6029316 Fabric Port Class 6 Output Drop Packets       0000000000000004  1,17 - 
6029327 Fabric Port Class 6 Output Drop Packets       0000000000229751  1,17,61 - 
6029328 Fabric Port Class 6 Output Drop Packets       0000000000307963  1,17 - 
6160386 Fabric Port Class 7 Output Drop Packets       0000000000000016  1,9,17 - 
6160388 Fabric Port Class 7 Output Drop Packets       0000000000000004  1,17 - 
6160399 Fabric Port Class 7 Output Drop Packets       0000000000228748  1,17,61 - 
6160400 Fabric Port Class 7 Output Drop Packets       0000000000307834  1,17 - 
6422530 Fabric Port Class 1 Output Drop Packets       0000000000000001  1,9,17 - 
6422532 Fabric Port Class 1 Output Drop Packets       0000000000000004  1,17 - 
6422543 Fabric Port Class 1 Output Drop Packets       0000000000000081  1,17,61 - 
6422544 Fabric Port Class 1 Output Drop Packets       0000000000000269  1,17 - 
6684672 Fabric Port Class 3 Output Drop Packets       0000000048748371  1,17 -

Conditions:
This counter increments even in extremely "quiet" environments with minimal data plane or control plane traffic. This counter is cosmetic in nature and is not indicative of any data plane or control plane packets being dropped.

These counters tend to increment mostly when an interface is being brought into an up/up status. As a result, a flapping interface may causes these counters to increment rapidly.
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