D-Link NetDefendOS User Manual page 300

Specifying Hosts
For each host specified for host monitoring, there are a number of property parameters that
should be set:
• Method
The method by which the host is to be polled. This can be one of:
• ICMP - ICMP "Ping" polling. An IP address must be specified for this.
• TCP - A TCP connection is established to and then disconnected from the host. An IP
address must be specified for this.
• HTTP - A normal HTTP server request using a URL. A URL must be specified for this as well
as a text string which is the beginning (or complete) text of a valid response. If no text is
specified, any response from the server will be valid.
• IP Address
The IP address of the host when using the ICMP or TCP option.
• Port Number
The port number for polling when using the TCP option.
• Source IP Selection
The source IP for the outgoing monitoring packets can be set to a specific value. By default,
the IP address of the sending interface is used (the Automatic option) but it can be set by
setting this property to Manual and specifying an IP address.
• Interval
The interval in milliseconds between polling attempts. The default setting is 10,000 and the
minimum value allowed is 100 ms.
• Sample
The number of polling attempts used as a sample size for calculating the Percentage Loss and
the Average Latency. This value cannot be less than 1.
• Maximum Failed Poll Attempts
The maximum permissible number of polling attempts that fail. If this number is exceeded
then the host is considered unreachable.
• Max Average Latency
The maximum number of milliseconds allowable between a poll request and the response. If
this threshold is exceeded then the host is considered unreachable. Average Latency is
calculated by averaging the response times from the host. If a polling attempt receives no
response then it is not included in the averaging calculation.
The Reachability Required Option
An important option that can be enabled for a host is the Reachability Required option. When
this is selected, the host must be determined as accessible in order for that route to be
considered to be functioning. Even if other hosts are accessible, this option says that the
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Chapter 4: Routing