IZ92922: TCP KEEPALIVE TIMER DOESN'T WORK WITH LARGE TCP_KEEPIDLE APPLIES TO AIX 5300-12

APAR status

• Closed as program error.

Error description

• If the large tcp_keepidle value is used (more than 31417
  if
  the default tcp_keepcnt and tcp_keepintvl valeus are
  used),
  then TCP connections will never be dropped even though
  the
  socket has valid SO_KEEPALIVE socket option and 8 probing
  packets are not acknowledged.
  

Local fix

• When the tcp_keepidle value needs to be changed, then use
  the following formula to calculate the maximum value of
  the
  tcp_keepidle value.
  .
  The maximum of the tcp_keepidle value = 32767 - ((
  tcp_keepcnt+1)*tcp_keepintvl)
  

Problem summary

• If the large tcp_keepidle value is used (more than 31417
  with the default tcp_keepcnt and tcp_keepintvl valeus),
  then TCP connections will never be dropped even though
  the socket has valid SO_KEEPALIVE socket option and 8 probing
  packets are not acknowledged.
  

Problem conclusion

• When user sets value for tcp_keepidle, the maximum value it
  can hold is restrictred with the following formula.
  
  The maximum of the tcp_keepidle value
  = 32767 - ((tcp_keepcnt+1)*tcp_keepintvl)
  
  This makes sure that connection gets dropped all the time.
  

Temporary fix

Comments

• 5300-12 - use AIX APAR IZ92922
  6100-06 - use AIX APAR IV29391
  6100-07 - use AIX APAR IV22417
  6100-08 - use AIX APAR IV17453
  7100-02 - use AIX APAR IV29844
  

APAR Information

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

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

  IV17453

Fix information

• Fixed component name

  AIX 5.3

• Fixed component ID

  5765G0300

Applicable component levels

• R530 PSY

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