The Question is:
TCP/IP V 4.0
How to adjust TCP-Segment (MMS) size? Our system tries to break down TCP
segments into IP packets with a maximum of 512 bytes of data. 'ucx> set proto
tcp /mtu ' has no effect (MTU-Size is 1500!).
The Answer is :
Please move to TCP/IP Services V4.2, or (better) please move to
OpenVMS VAX V7.2 or later with TCP/IP Services V5.1 and later,
and with appropriate ECO kits applied.
On releases as old as V4.2, you will want to use the logical name
UCX$FTP_WNDSIZ to control the FTP window size, if that is the
protocol of interest.
With V4.x series releases and YOU MUST HAVE THE CURRENT ECO KITS
INSTALLED, use the commands:
SET CONF COMM/TYPE=DEFAULT
SET CONF COMM/TYPE=FDDI
SET CONF COMM/TYPE=ETHER
SET PROTOCOL TCP /MTU_SEGMENT_SIZE
IPv6 eliminates much of the "fun" involved here.