User`s guide

7UPS Network Management Card 2 User’s Guide
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: Network Interface
restarted 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 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.