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Cisco Bug: CSCvt85115 - M3 traffic blackholed with vqi drops after SSO and SLF_VAM_FLN_AM_INT_ERR_COL_CNTR_OVERFLOW

Last Modified

May 07, 2020

Products (1)

  • Cisco Nexus 7000 Series Switches

Known Affected Releases

8.2(5)

Description (partial)

Symptom:
1. Input discards associated with one or more egress port (VQI) causing black-holing of traffic

show hardware internal error module <> | beg "Role:QUE"

show hardware internal error module 4
 
|------------------------------------------------------------------------|
| Device:SLF VQ                   Role:QUE                     Mod: 4    |
| Last cleared @ Sat Mar 28 01:13:56 2020
| Device Statistics Category :: CONGESTION
|------------------------------------------------------------------------|
Instance:0
Cntr   Name                                          Value            Ports
------ ----                                          -----            -----
35050  VIR src 11 vl 0 tail drop                     0000000000300968 24 -     
35058  VIR src 11 vl 1 tail drop                     0000000000075532 24 -     
43775  VIR vqi 947 cl 0 drop count                   0000000000000002 1-24 -   
43810  VIR vqi 951 cl 3 drop count                   0000000000000003 1-24 -   
43855  VIR vqi 957 cl 0 drop count                   0000000000007261 1-24 -   
43856  VIR vqi 957 cl 1 drop count                   0000000000000026 1-24 -   
43857  VIR vqi 957 cl 2 drop count                   0000000000000015 1-24 -   
43858  VIR vqi 957 cl 3 drop count                   0000000000001212 1-24 -   
44034  VIR vqi 979 cl 3 drop count                   0000000000003389 1-24 -   
44146  VIR vqi 993 cl 3 drop count                   0000000000115087 1-24 -    <<<< vqi 993 (0x3e1) maps to egress 4/36

convert vqi decimal value to hex ,  e.g. hex 993 = 0x3e1  and to find the corresponding egress interface  

show system internal ethpm info all  | in ^Ethernet|VQI | in 0x3e1 previous 1
Ethernet4/36 - if_index: 0x1A1A3000
    LTL(0x55), VQI(0x3e1), LDI(0x2f), IOD(0xc0)                              <<<<<  vqi 0x3e1 (=dec 993) maps to e4/36


2. Presence of Overflow interrupt errors reported by the module onboard exception-log minutes following Sup Switchover

show logging onboard module < > exception-log  | in ig overflow

Error Description : SLF_VAM_FLN_AM_INT_ERR_R_CNTR_OVERFLOW
Error Description : SLF_VAM_FLN_AM_INT_ERR_B_CNTR_OVERFLOW
Error Description : SLF_VAM_FLN_AM_INT_ERR_G_CNTR_OVERFLOW
Error Description : SLF_VAM_FLN_AM_INT_ERR_COL_CNTR_OVERFLOW

Conditions:
After supervisor switchover (or an upgrade/downgrade that causes SSO).
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