IV17806: KEEPALIVE PACKETS HAVE ZERO WINDOW SIZE WHEN RFC1323 IS OFF. APPLIES TO AIX 5300-12

APAR status

• Closed as program error.

Error description

• If rfc1323 window scaling is NOT in effect AIX keepalive
  packets may have a small or zero window size even when
  the
  AIX recv-q is empty. This requires the remote side to
  send
  and process a window probe exchange before resuming
  transmission.
  

Local fix

• Disable keepalive socket option in application or enable
  rfc1323 on both ends of connection.
  

Problem summary

• Environment with lowered  keepalive intervals will have
  performance impact when rfc1323 scalling is disabled.
  
  If rfc1323 window scaling is NOT in effect AIX keepalive
  packets may have a small or zero window size even when
  the AIX recv-q is empty. This requires the remote side to
  send and process a window probe exchange before resuming
  transmission.
  

Problem conclusion

• The window size is correctly advertized in all cases
  with keep alive packet. This avoids the performance issue
  created due to small window advertizement.
  

Temporary fix

Comments

• 5300-12 - use AIX APAR IV17806
  6100-05 - use AIX APAR IV13929
  6100-06 - use AIX APAR IV14145
  6100-07 - use AIX APAR IV01302
  7100-02 - use AIX APAR IV29845
  

APAR Information

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

  IV01302

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

Fix information

• Fixed component name

  AIX 5.3

• Fixed component ID

  5765G0300

Applicable component levels

• R530 PSY

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