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IV18483: TCP RETRANSMIT PROCESSING IS VERY SLOW APPLIES TO AIX 6100-06

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APAR status

  • Closed as program error.

Error description

  • The first retransmit packet may be sent after 64 seconds,
so the application will suffer from the slow TCP data
transfer. At that time, the routing entry will show very
high rtt/rttvar value:
.
# route get <ip>
......
recvpipe  sendpipe  ssthresh  rtt,msec    rttvar ...
0         0         0     61847   1058704  ...

Local fix

  • N/A

Problem summary

  • ****************************************************************
* USERS AFFECTED:
* Users of TCP/IP on systems running the 6100-06 Technology
* Level.
****************************************************************
* PROBLEM DESCRIPTION:
* TCP/IP communication can be very slow due to retransmit
* processing.  The first retransmit packet may be sent after
* 64 seconds.  During this time the routing entry will show
* very high rtt/rttvar values.
*
* Possible workaround is:
* Turn off the rfc1323 using the chdev command or the
*    ifconfig command. Example of chdev command is
*
*   chdev -l enX -a rfc1323=0
*
* This problem only occurs when the timestamp is used
* for RTT calculation. Note that you can use the ifconfig
* command to temporarily disable rfc1323 for testing purposes.
* The chdev command alters the ODM so customer values
* return after a system reboot.
****************************************************************
* RECOMMENDATION:
* Install APAR IV18483.
*
* Prior to APAR availability, and interim fix is available from:
* ftp://public.dhe.ibm.com/aix/ifixes/iv18483/
****************************************************************
.

Problem conclusion

  • When customer disables tcp timestamp randomization feature,
Randomized timestamp value is not used for setting
the retransmission timer. This fixes the above mentioned
issue.

Temporary fix

  • *********
* HIPER *
*********

Comments

  • 6100-06 - use AIX APAR IV18483
7100-00 - use AIX APAR IV20595

APAR Information

  • APAR number

    IV18483

  • Reported component name

    AIX 610 STD EDI

  • Reported component ID

    5765G6200

  • Reported release

    610

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Submitted date

    2012-03-29

  • Closed date

    2012-03-29

  • Last modified date

    2013-03-26

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

    IV13121

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

Fix information

  • Fixed component name

    AIX 610 STD EDI

  • Fixed component ID

    5765G6200

Applicable component levels

  • R610 PSY U849886

       UP12/06/12 I 1000

PTF to Fileset Mapping

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Document Information

Modified date:
26 March 2013

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