Question:

Why does TCPware hang after installing VMS eco?

Answer:

A change included in the VMS LAN ecos (LAN eco 0700 for VMS 7.3-2,
the corresponding UPDATE ecos, and likely others for VMS 8.x) can
cause all versions of TCPware to hang. This problem is fixed in
drivers eco DRIVERS_V5092P020 for TCPware 5.9-2.

This problem appears as TCPware being unable to receive any network
packets after having received 5000 packets. Problems can also
appear after receiving 5000 ARP or RARP packets.

This problem is easily worked around by setting bit 16 (0x10000 hex)
in the system parameter LAN_FLAGS using SYSGEN or SYSMAN as
appropriate. Fortunately, this parameter is dynamic and therefore
a system reboot is not required.