Troubleshooting
Problem
Idle DDM connections may be ended by network appliance if the CHGTCPA keepalive value is too high.
Symptom
Message CPD3E34:
DDM TCP/IP communications error occurred on recv() - MSG_PEEK.
...will be present in the client-side job log.Also, a WRKPRB entry may be generated with the following symptom string:
5770 F/QCNXDUMP MSGCPF9158 PRCS/40
Cause
Too high a value for TCP keep alive / TCPKEEPALV in CHGTCPA on client system and too low of an idle connection setting on a network appliance.
Diagnosing The Problem
Client job log may contain messages:
CPE3424 Diagnostic 10 04/26/16 11:50:08.864855 QRWXDLL QSYS *STMT QRWXDLL QSYS *STMT
From module . . . . . . . . : QRWXDLL
From procedure . . . . . . : SndErrnoMsg__FPc
Statement . . . . . . . . . : 13
To module . . . . . . . . . : QRWXDLL
To procedure . . . . . . . : SndErrnoMsg__FPc
Statement . . . . . . . . . : 13
Message . . . . : Connection ended abnormally.
CPD3E34 Diagnostic 40 04/26/16 11:50:08.869961 QRWXDLL QSYS *STMT QRWXDLL QSYS *STMT
From module . . . . . . . . : QRWXDLL
From procedure . . . . . . : SndCPD3E3x__FiT1
Statement . . . . . . . . . : 23
To module . . . . . . . . . : QRWXDLL
To procedure . . . . . . . : SndCPD3E3x__FiT1
Statement . . . . . . . . . : 23
Message . . . . : DDM TCP/IP communications error occurred on recv() -
MSG_PEEK.
Cause . . . . . : Error code (errno) 3424 was received while processing the
recv() - MSG_PEEK function for DRDA/DDM TCP/IP communications.
CPF9158 Diagnostic 40 04/26/16 11:50:08.901025 QCNSMCTL QSYS *STMT
From module . . . . . . . . : QCNSMCTL
From procedure . . . . . . : QCNSMCTL
Statement . . . . . . . . . : 3036
To module . . . . . . . . . : XXXXXXX
To procedure . . . . . . . : XXXXXXX
Statement . . . . . . . . . : 2100000001
Message . . . . : DDM communications request failed.
Resolving The Problem
Lower the IBM i TCPKEEPALV value from the default of 120 minutes to something lower than what will trigger the network appliance to end the idle connection. For example:
CHGTCPA TCPKEEPALV(45)
Alternatively, raise the idle connection timer in the network appliance.
Communications traces (TRCCNN) may be taken concurrently on both the client and server to verify the behavior. Recommended trace output format is .pcap so that network administrators can review using Wireshark.
Related Information
[{"Product":{"code":"SWG60","label":"IBM i"},"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Component":"Communications-TCP","Platform":[{"code":"PF012","label":"IBM i"}],"Version":"Version Independent","Edition":"","Line of Business":{"code":"LOB57","label":"Power"}}]
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Document Information
Modified date:
15 March 2022
UID
nas8N1021307