PI93670: OUT OF ORDER PACKETS WITH LARGE SENDS OR SEGMENTATION OFFLOAD.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• SYSTCPDA packet trace shows packets leaving in order however
  OSAENTA trace shows some packets being sent out of order. VTAM
  trace showed the packets being sent out of order on the session
  were segmentation offload packets and the Q Priority for these
  packets were dropping to a 3 while the small packets had a Q
  Priority of 4. With all packets having the same TOS value and
  NOWLMPRIORITYQ being set then all packets should have the same Q
  Priority.
  

Local fix

• Disable ZIIP IQDIOMULTIWRITE until the apar is applied.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All users of the IBM Communications Server for z/OS Version  *
  * 2 Releases 1, 2, and 3: OSA-Express QDIO when ZIIP           *
  * IQDIOMULTIWRITE is in effect                                 *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * Out-of-order packets over OSA-Express QDIO                   *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Apply PTF                                                    *
  ****************************************************************
  The stack was incorrectly transmitting large socket sends on the
  wrong outbound priority queue for OSA-Express QDIO when ZIIP
  IQDIOMULTIWRITE is in effect which was causing out-of-order
  transmission between large and small sends for the same TCP
  connection
  

Problem conclusion

• Correct stack logic to properly set the outbound priority queue
  for sends over OSA-Express QDIO
  

Temporary fix

Comments

APAR Information

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

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

  UI53953 UI53970 UI53971

Modules/Macros

• EZBIFOUT
  

Fix information

• Fixed component name

  TCP/IP MVS

• Fixed component ID

  5655HAL00

Applicable component levels

• R230 PSY UI53953

     UP18/03/13 P F803

• R220 PSY UI53971

     UP18/03/13 P F803

• R210 PSY UI53970

     UP18/03/13 P F803

Fix is available

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