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Status Delivered
Workspace AIX
Created by Guest
Created on Jun 9, 2015

First TCP/IP Retransmission time too long(1.5 seconds or so)

[ Request ]
Customer want to shorten the initial TCP/IP retransmission timeout (currently 1500 msec) of AIX since response performance is important their financial trading system.

In PMR 76617,695,760, we have confirmed that current initial TCP/IP retransmission timeout(1500 msec) is design of AIX. We need to change the design to meet the customer requirement for their system.

If AIX can not meet the customer requirement, their financial trading system will be replaced frm AIX to x86/Linux.
We cannot choose Linux on Power becase customer's standard operational software is not supported on Linux on Power.

[ Current TCP/IP retransmission behaviour of AIX and Linux ]

AIX with "Timer wheel algorithm for fine granularity retransmission" (timer_wheel_tick=1 / tcp_low_rto=20):
retransmission interval of 1st packet : 1500, 36, 64, 150, 286 msec .....
retransmission interval of 2nd packet : 106, 210, 450, 836 msec ....

Linux (redhat 7.1 / x86):
retransmission interval of 1st packet : 203, 204, 408, 819, 1603 msec .....
retransmission interval of 2nd packet : 203, 204, 409, 818 msec ....

[ Environment]
Power 780(9179-MHB)
VIOS V2.2.2.3
AIX V6.1 TL06

Idea priority Urgent
  • Guest
    Nov 7, 2016

    .delivered in AIX7.2 TL1 and AIX7.1 TL4 SP3

  • Guest
    May 3, 2016

    ifix delivered. to appear in 2016 releases

  • Guest
    Jun 11, 2015

    Creating a new RFE based on Community RFE #72542 in product IBM AIX.