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Network Management Card User’s Guide 5
Introduction
Watchdog Features
Overview
The Management Card is designed to recover from unanticipated
inputs. Through the use of internal, system-wide watchdog
mechanisms, the Management Card can detect most internal problems.
When it does, it reboots itself to recover from the internal problem. This
results in a System: Warmstart event being recorded in the event log.
Network
interface
watchdog
mechanism
The Management Card implements numerous internal watchdog
mechanisms to protect itself from becoming inaccessible over the
network. One of these mechanisms ensures that the Management Card
can receive network traffic: If within a 9.5-minute period the
Management Card does not receive any network traffic (either direct,
like SNMP, or broadcast, like an Address Resolution Protocol [ARP]
request) then it will assume that there is a problem with its network
interface and reboot itself.
The role of the
Default Gateway
in resetting
the network
timer
Most networks will have some level of broadcast traffic which will be
received by the Management Card and reset the 9.5-minute timer back
to zero. But it is possible (for example, late at night in an accounting
department) that the Management Card will not see any traffic for 9.5
minutes. Since it is not desirable for the Management Card to reboot
just because the network is quiet, the Management Card will attempt to
contact the Default Gateway once every 4.5 minutes. If the gateway is
present, it will respond to the Management Card and the 9.5-minute
timer will be reset to zero.
If your application does not require a gateway or does not have one,
specify the IP address of a computer on the same subnet which is up
and running on the network most of the time. This will have the same
effect as configuring a gateway.