This article explains how to troubleshoot following cmerror seen on PTX devices :

Jul 24 20:52:31 2023  abc resiliencyd[11783]: Performing action log for error /fpc/3/evo-cda-zx/0/cm/0/zxchip/3/igp_intr_pkt_trapcode (0x420a84) in module: zxchip with scope: pfe category: functional level: minor

Below logs will be seen in the message logs on the device :

Jul 24 20:52:31 2023  abc resiliencyd[11783]: Performing action log for error /fpc/3/evo-cda-zx/0/cm/0/zxchip/3/igp_intr_pkt_trapcode (0x420a84) in module: zxchip with scope: pfe category: functional level: minor
Jul 24 20:52:31 2023  abc resiliencyd[11783]: Cmerror Op Clear: zxchip:  (URI: /fpc/3/evo-cda-zx/0/cm/0/zxchip/3/igp_intr_pkt_trapcode)
Aug  6 18:06:34 2023  abc resiliencyd[11783]: <FPC 2> ASIC Error detected errorno 0x00000a84
 

IGP errors will be incrementing in the "show pfe statistics error" output. If the cmerrors are no longer seen, IGP errors will have a non zero value but not incrementing. Sample output with high IGP errors (output only shows non zero values ) :

cli> show pfe statistics error

PFE Error Stats

ASIC Errors:

ASIC Instance   0

IGP errs received from IQM/DBM :   10

ASIC Instance   1

IGP errs received from IQM/DBM :   2

ASIC Instance   2

IGP errs received from IQM/DBM :   17

ASIC Instance   3

IGP errs received from IQM/DBM :   0

ASIC Instance   4

IGP errs received from IQM/DBM :   535

ASIC Instance   5

IGP errs received from IQM/DBM :   93513

ASIC Instance   6

IGP errs received from IQM/DBM :   729

ASIC Instance   7

IGP errs received from IQM/DBM :   1535

ASIC Instance   8

IGP errs received from IQM/DBM :   1

ASIC Instance   9

IGP errs received from IQM/DBM :   18256

ASIC Instance   10

IGP errs received from IQM/DBM :   2655

ASIC Instance   11

IGP errs received from IQM/DBM :   3183

ASIC Instance   12

IGP errs received from IQM/DBM :   9

ASIC Instance   13

IGP errs received from IQM/DBM :   2571

ASIC Instance   14

IGP errs received from IQM/DBM :   103097

ASIC Instance   15

IGP errs received from IQM/DBM :   367

ASIC Instance   16

IGP errs received from IQM/DBM :   11674

ASIC Instance   21

IGP errs received from IQM/DBM :   128
 

ASIC Instance   30

IGP errs received from IQM/DBM :   131

IQM ( Ingress Queue manager ) receives the packet from the WAN port and forwards the packet to the ingress packet processor blocks. Of these blocks, IGP ( Ingress Parser ) is the first block that receives the packet.

IGP block is responsible for the below actions :

• Parses the packet header (ie. header validation and L2-L4 key extraction).
• Control Packet Classification (ie. hostbound packets), resulting in a
• Sets trapcode for various ‘exception’ events (ie. IPv4 header checksum error )
• Detect packet header checksum error
• Generates load-sharing hash
• Passes key / notification data to the Source Lookup (SLU) sub-block

If the incoming packet has malformed IP header, the associated trapcode is set in the IGP block and the below logs are printed stating that cmerror is set for the FPC receiving the packet with malformed header.

Jul 25 00:11:00 2023  abc resiliencyd[11783]: Error: /fpc/3/evo-cda-zx/0/cm/0/zxchip/3/igp_intr_pkt_trapcode (0x420a84), scope: pfe, category: functional, severity: minor, module: zxchip, type: igp_intr_pkt_trapcode
Jul 25 00:11:00 2023  abc resiliencyd[11783]: Cmerror Op Set: zxchip:  (URI: /fpc/3/evo-cda-zx/0/cm/0/zxchip/3/igp_intr_pkt_trapcode)
Aug  6 18:06:34 2023  abc resiliencyd[11783]: <FPC 2> ASIC Error detected errorno 0x00000a84

You can login to the FPC shell and confirm which trapcode is getting set :

start shell pfe network fpc<fpc slot number for which the cmerror is reported>

show cda trapcode all    << this output will explain the meaning of all trapcodes

show cmerror statistics  << this output will show the count of all cmerror set

show cda trapstats       << collect multiple iterations of this output at an interval of 2 mins to narrow down the error code that is incrementing.
 

Once you have identified the reason behind the IGP trapstats, you will need to trace source of such packets and block them or else those packets will continue to be rightly dropped and cmerrors will be set and cleared for the FPC. To find the source of the packets parcel dumps can be used to dump the packets.

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