Link Monitoring And Ha - D-Link DFL-1660 User Manual

11.6. Link Monitoring and HA

11.6. Link Monitoring and HA
Redundant Network Paths
When using an HA configuration, it can be important to use redundant paths to vital resources such
as the Internet. The paths through the network from the master device in an HA configuration may
fail in which case it may be desirable to have this failure trigger a failover to the slave unit which
has a different path to the resource.
Monitoring Paths
Monitoring the availability of specific network paths can be done with the NetDefendOS Link
Monitor. The Link Monitor allows the administrator to specify particular hosts whose reachability is
monitored using ICMP "Ping" requests and therefore link status. If these hosts become unreachable
then the link is considered failed and a failover to a slave can be initiated. Provided that the slave is
using a different network link and also monitoring the reachability of different hosts, traffic can
continue to flow.
Using the Shared IP Address
When using the Link Monitor in a High Availability cluster the option Send from Shared IP
Address will be visible during Link Monitor setup. This option can be used if individual public
IPv4 addresses are not available for each unit in an HA cluster.
Further Link Monitor Reading
Link monitoring as a NetDefendOS feature separate from HA is described further in Section 2.4.1,
"The Link Monitor".
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Chapter 11. High Availability