APC Network Management Card AP9617 - Manual (Page 9)

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USER’S GUIDE
network management card
7
Watchdog Features
Overview
To detect internal problems and recover from unanticipated inputs, the
Management Card uses internal, system-wide watchdog mechanisms.
When it reboots itself to recover from an internal problem, a
System:
Warmstart event is recorded in the Event Log.
Network interface watchdog mechanism
The Management Card implements internal watchdog mechanisms to
protect itself from becoming inaccessible over the network. For example, if
the Management Card 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 reboots itself.
Resetting the network timer
To ensure that the Management Card does not reboot if the network is quiet
for 9.5 minutes, the Management Card attempts to contact the Default
Gateway every 4.5 minutes. If the gateway is present, it responds to the
Management Card, 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 Management Card from rebooting.