Turn off TCP Window Scaling

Answer

At IBM i 7.1 you can now turn off "TCP WINDOW SCALING with PTF MF57230(TL3298) and
MF56924(TL3298).


APAR MA42179 notes the following defined in RFC1323 / RFC 1323:
Provides the ability to disable TCP timestamp responses and window scaling.

Options were added to the IPCONFIG Advanced Analysis command
available through System Service
Tools (STRSST).

To change the settings with the STRSST command, use the following steps:
On the command line: Open a character-based interface/5250 emulation session:

1) STRSST.
2) Type your service tools user name and password.
3) Select option 1 (Start a service tool).
4) Select option 4 (Display/Alter/Dump).
5) Select option 1 (Display/Alter storage).
6) Select option 2 (Licensed Internal Code (LIC) data).
7) Select option 14 (Advanced Analysis).
8) Select option 1 (IPCONFIG).
9) Specify option '-h' to display configuration options.

The two new IPCONFIG options for RFC1323 are:

1) -rfc1323TcpTimestamps:<on,off>

2) -rfc1323TcpWindowScaling:<on,off>

Note: When TCP RCVBUF is higher than 64K and window scaling is off, 64K will be used. TCP takes the
minimum of RCVBUF and calculated window size using window size scaling factor.