Troubleshooting
Problem
When using the NJE over TCP/IP function of JES2 (new in z/OS 1.8, enabled in 1.7 with APAR OA12364) or JES3 (new in z/OS 1.8), the connection occasionally fails with the Socket Not Connected messages. These messages will likely occur on both JES nodes involved in the connection at almost the same time.
Symptom
For JES2, the following messages may be issued:
IAZ0545I njetcp line Error encountered in function getpeername() - EDC8124I Socket not connected.
IAZ0543I njetcp line TCP/IP connection with IP Addr: rmt_ipaddr Port rmt_port ended due to TCP/IP error, rc: 1124
IAZ0544I njetcp line NJE connection with IP Addr: rmt_ipaddr Port: rmt_port ended due to TCP/IP error
$HASP203 nodename DISCONNECTED FROM line
Cause
The most likely explanation is some form of packet loss between the two systems. This could include temporary communication failures along the network path or a firewall closing the connection for inactivity.
Diagnosing The Problem
Do not spend time trying to analyze the errno (ENOTCONN) reported for the getpeername() call. It is merely the first call issued after the real failure.
Collect a packet trace (SYSTCPDA CTRACE) on both systems involved in the connection (see Technote 1292013 for step by step directions to collect this using an external writer). You may also want to have your local network support group collect network analyzer (for example, sniffer) traces at the same time. Review the traces as a TCP connectivity problem. Also, use the TRACERTE command from both systems while this failure is occurring to identify where along the network path packets are being lost.
Resolving The Problem
- Correct any network communication problems.
- If a firewall is shutting down the connection for inactivity, decrease the keep alive time (INTERVAL value on the TCPCONFIG statement in the TCPIP PROFILE) used by either system to be shorter than the firewall's time-out value.
- Add automation on the IAZ0544I message to automatically restart the NJE line.
Related Information
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Document Information
Modified date:
03 September 2021
UID
swg21283994