User guide

User Guide InfraStruxure 150kVA Power Distribution Unit 4
Watchdog Features
Overview
To detect internal problems and recover from unanticipated inputs, the NMC uses internal, system-wide
watchdog mechanisms. When it restarts to recover from an internal problem, a System: Warmstart
event is recorded in the event log.
Network interface watchdog mechanism
The NMC implements internal watchdog mechanisms to protect itself from becoming inaccessible over
the network. For example, if the NMC does not receive any network traffic for 9.5 minutes (either direct
traffic, such as SNMP, or broadcast traffic, such as an Address Resolution Protocol [ARP] request), it
assumes that there is a problem with its network interface and restarts.
Resetting the network timer
To ensure that the NMC does not restart if the network is quiet for 9.5 minutes, the NMC attempts to
contact the default gateway every 4.5 minutes. If the gateway is present, it responds to the NMC, and that
response restarts the 9.5-minute timer. If your application does not require or have a gateway, specify the
IP address of a computer that is running on the network most of the time and is on the same subnet. The
network traffic of that computer will restart the 9.5-minute timer frequently enough to prevent the NMC
from restarting.