IJ03186: SMALL TCP PACKETS SENT VIA SEA MAY BE DROPPED APPLIES TO AIX 6100-09

APAR status

• Closed as program error.

Error description

• **************************************************************
  * USERS AFFECTED:
  * Systems running VIOS 2.2.x.x
  * with devices.ethernet.mlx.rte at the
  * 6.1.9.300 or 6.1.9.315 level.
    **************************************************************
  * ERROR DESCRIPTION:
  * Small TCP packets sent via SEA to certain adapters, with
  * checksum offload enabled, may not get the proper TCP
  * checksum and be dropped by the receiving side.
  *
  * We have seen this issue occur with real adapters in the
  * VIOS using the mlxentdd driver.
  * Find out if the VIOS has any adapters using an affected
  * driver with lsdev; for example:
  *
  * # lsdev -F "name ddins" | grep mlxentdd
  *
  * Note: on VIOS, this must be run as root using 'oem_setup_env'.
  *
  * We have seen the small TCP packets coming from various
  * sources including:
  * - IBMi client LPARs
  * - hosts on the network with TCP features like timestamps
  * disabled
    **************************************************************
  * RECOMMENDATION:
  * Install APAR IJ03186.
  * Prior to fix availability, an interim fix is available from
  * either
  * ftp://aix.software.ibm.com/aix/ifixes/ij03186/
  * https://aix.software.ibm.com/aix/ifixes/ij03186/
  * Installation of the ifix requires a reboot.
    **************************************************************
  

Local fix

Problem summary

• Small TCP packets sent via a SEA with checksum offload
  enabled will not have the proper TCP checksum on the
  receiving side.
  

Problem conclusion

• Fixed the code in network device driver to properly handle
  packets less than supported min packet size.
  

Temporary fix

•   *********
    * HIPER *
    *********
  

Comments

• 6100-09 - use AIX APAR IJ03186
  6100-09 - use AIX APAR IJ03186
  6100-09 - use AIX APAR IJ03186
  7100-05 - use AIX APAR IJ04407
  7100-05 - use AIX APAR IJ04407
  7200-02 - use AIX APAR IJ06064
  

APAR Information

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

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

  IJ04211 IJ04407 IJ05162 IJ06062 IJ06063 IJ06064

Fix information

• Fixed component name

  VIRTUAL I/O SER

• Fixed component ID

  5765G3400

Applicable component levels