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MF50394 - LIC-COMM-TCPIP-UNPRED RETRANSMISSION TIMER HIGH

PTF Cover Letter


PTF ( Program Temporary Fixes ) Cover letter


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Abstract

LIC-COMM-TCPIP-UNPRED RETRANSMISSION TIMER HIGH


Pre/Co-Requisite PTF / Fix List

REQ  LICENSED      PTF/FIX  LEVEL

TYPE PROGRAM  REL  NUMBER   MIN/MAX  OPTION
---- -------- ---  -------  -------  ------
CO   5770999  710  MF49821   00/00    0000



NOTICE:
-------
Application of this PTF may disable or render ineffective programs that
use system memory addresses not generated by the IBM translator,
including programs that circumvent control technology designed to limit
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foregoing.

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REGARDING THE PTF.





APAR Error Description / Circumvention

-----------------------------------------------
System i socket application makes a connection to a remote
system. The SYN packet is sent. There is no response. Then a
retransmitted SYN is sent. A SYN ACK is received after 7 seconds
for the first SYN packet. Due to this delay of the SYN ACK
coming back, the retransmission timer is set very high. Later,
in the connection a user data packet is sent, but there is no
ACK. The sockets application closes the socket after 30 seconds,
before the retransmission occurs. The retransmission should be
sent much sooner.

CORRECTION FOR APAR MA38923 :
-----------------------------
The retransmission of the very first packet sent takes us down a
rarely-traveled code path. There has not been a packet received
yet for the connection, so the calculations are done differently
for this case. There is a bug in this section of code for
calculating the retransmit timer.  This will be corrected.

CIRCUMVENTION FOR APAR MA38923 :
--------------------------------
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
--------------  ------------------------------------------------------------
   MF49877      LIC-COMM-TCPIP TCP Buffer Copy Prevention

Summary Information

System..............................i
Models..............................
Release.............................V7R1M0
Licensed Program...............5770999
APAR Fixed..........................View details for APAR MA38923
Superseded by:......................View fix details for PTF MF99011
Recompile...........................N
Library.............................QSYS
MRI Feature ........................NONE
Cum Level...........................C1116710


System i Support

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Document Information

Modified date:
07 June 2010