PK57469: RESET PACKET NOT SENT AFTER COMPLETION OF 10 KEEPALIVE PACKETS

APAR status

• Closed as fixed if next.

Error description

• When there is no response to a keepalive packet another
  keepalive is sent after 75 seconds.   TCPIP will continue to
  send keepalive packets every 75 seconds if there is no
  response until 10 keepalive packets have been sent.   At that
  point the connection is aborted and TCPIP cleans up the
  connection and reports the aborted connection the the local
  application but no RESET packet is sent to the remote side.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of the IBM Communications Server   *
  *                 for z/OS Version 1 Release(s) 8 and 9 IP     *
  ****************************************************************
  * PROBLEM DESCRIPTION: RST packet not sent to the remote when  *
  *                      a TCP connection keepalive timeout      *
  *                      occurs.                                 *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  TCP connection with keepalive enabled becomes a keepalive probe
  being sent.  If an ACK in response to the keepalive probe is not
  received further keepalive probes will be sent until a timeout
  is recognized.  The local socket end point will have an
  ETIMEDOUT error presented and the local connection is set to the
  KLOSED state.  The keepalive timeout failure does not cause a
  RST packet to be sent to the peer.
  The lack of an ACK response may be due to an error in the return
  network path or a firewall may be blocking the keepalive probes.
  There is a possibility of the RST packet successfully reaching
  the peer, thus the keepalive timeout failure should send a RST.
  +-------------------------------------------------------------+
  + Please check our Communications Server for OS/390 homepages +
  + for common networking tips and fixes.  The URL for these    +
  + homepages can be found in Informational APAR II11334.       +
  +-------------------------------------------------------------+
  

Problem conclusion

• This APAR is fixed in HIP6180, HIP6190 and HIP61A0 by APAR
  PK77591
  

Temporary fix

Comments

• This APAR is being closed FIN (Fixed If Next) with concurrence
  from the submitting customer. This means that a fix to this
  APAR is expected to be delivered from IBM in a release (if any)
  to be available within the next 24 months.
  
  This problem will be tracked as Feature F143207
  by Communications Server for z/OS Development.
  
  The solution for this APAR is included in CS for z/OS Version 1
  Release 11.
  

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

Applicable component levels

• R180 PSN

     UP

• R190 PSN

     UP