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MF67895 - OSP-UNPRED TCP/IP WINDOW GETTING SHUT DOWN

PTF Cover Letter


PTF ( Program Temporary Fixes ) Cover letter


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Abstract

OSP-UNPRED TCP/IP WINDOW GETTING SHUT DOWN


Pre/Co-Requisite PTF / Fix List

REQ  LICENSED           PTF/FIX  LEVEL

TYPE PROGRAM  RELEASE   NUMBER   MIN/MAX  OPTION
---- -------- --------- -------  -------  ------
NONE



NOTICE:
-------
Application of this PTF may disable or render ineffective programs that
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APAR Error Description / Circumvention

-----------------------------------------------
Customer pages up and down quickly on HMC console and it
freezes, then comes back. Looks like a disconnect followed by
reconnect. DSP01 device error is logged.

CORRECTION FOR APAR MA48659 :
-----------------------------
The TCP/IP service stack tracks how much received data has been
passed up to the server (console in this case) to manage flow
control for a TCP session. If this indicates a large amount of
data has been sent to the server but not processed, TCP flow
control eventually results in advertising a zero window which
does not allow any more data to be sent on the connection. When
that state persisted, the console froze and then established a
new TCP session.

The tracking of outstanding data sent to the server used a
length field that was being altered by the server as it
processed that data and this caused the outstanding data count
to be incorrect. The service stack has been changed to manage
the outstanding data count with only internal service stack
information rather than a field that's shared with the server.
This will prevent TCP from incorrectly entering flow control.

CIRCUMVENTION FOR APAR MA48659 :
--------------------------------
None.


Activation Instructions


None.




Special Instructions


None.


Default Instructions

THIS PTF CAN BE APPLIED IMMEDIATE OR DELAYED.



Supersedes

PTF/FIX NO(S).  APAR TITLE LINE
--------------  ------------------------------------------------------------
     NONE

Summary Information

System..............................i
Models..............................
Release.............................V7R3M0
Licensed Program...............5770999
APAR Fixed..........................View details for APAR MA48659
Superseded by:......................
Recompile...........................N
Library.............................QSYS
MRI Feature ........................NONE
Cum Level...........................C1098730


IBM i Support

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Document Information

Modified date:
17 April 2021