Troubleshooting
Problem
The distributed DB2 server is working properly most of the time, but there are several instances where connection failures are being logged for a variety of client IP addresses. There might not be any other reported problems being caused by these failures.
Symptom
DSNL511I DSNLIENO TCP/IP CONVERSATION FAILED
TO LOCATION xx.xx.xx.xx
IPADDR=xx.xx.xx.xx PORT=yyyyy
SOCKET=RECV RETURN CODE=1121 REASON CODE=00000000
Return Code 1127 may also be reported.
Cause
The reported return code is a sockets call errno. 1121 is ECONNRESET, which means that a TCP RESET packet was received that terminated the connection. There are many possible reasons why a client system would send a RESET packet, and you should determine whether it issued any messages about these sessions.
But if these messages are repeatedly being generated for a variety of IP addresses, an intermediate firewall is probably terminating sessions that have not had any activity for a predefined period. Confirm the cause by contacting the firewall administrator and having them check the firewall system's logs at the times of the DSNL511I messages.
Return Code 1127 is ETIMEDOUT. This will occur when there is no response to the KeepAlive packets sent on the connection. This can be caused by clients that are no longer responsive (or no longer connected to the network). But repeated instances are likely associated with a firewall that silently discards packets for sessions that it has timed out for inactivity.
Diagnosing The Problem
A packet trace collected to an external writer with the filter PORTNUM=Db2ListenPort specified will show the TCP layer traffic involved.
Resolving The Problem
Determine what timeout value has been configured on the firewall. Using the DDF Installation CLIST, go to DDF Panel 2 (DSNTIP5), set TCP/IP Keepalive (TCPKPALV) to a value shorter than the firewall's timeout. Alternatively, this can be set to the value ENABLE if the INTERVAL value on the TCPCONFIG statement in the TCPIP PROFILE is already shorter.
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Document Information
Modified date:
15 June 2018
UID
swg21396266