D-Link DFL-260E User Manual for DFL-260E - Page 178
Reachability Required, IP Address, Port Number, Interval, Sample, Maximum Failed Poll Attempts
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4.2.4. Host Monitoring for Route Failover Chapter 4. Routing 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. • 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 accessibility of a host with this option set is mandatory. Where multiple hosts are specified for host monitoring, more than one of them could have Reachability Required enabled. If NetDefendOS determines that any host with this option enabled is not reachable, Route Failover is initiated. HTTP Parameters If the HTTP polling method is selected then two further parameters can be entered: • Request URL The URL which is to be requested. 178