USRobotics NETServer/8 - Manual (Page 162)

10-12 Command Reference
ICMP Logging
This command determines whether the NETServer sends ICMP
errors such as Host Unreachable to the Syslog server. The
default is off, which means that the NETServer does not pass
such messages to Syslog.
set icmplogging < on | off>
Note that the NETServer must be configured to use Syslog
network accounting (see Syslog Accounting).