Amer Networks E5Web GUI - Manual (Page 268)

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 cOS Core 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.
• Expected Response
The text that is expected back from querying the URL.
Testing for a specific response text provides the possibility of testing if an application is
offline. If, for example, a web page response from a server can indicate if a specific database is
operational with text such as "Database OK", then the absence of that response can indicate
that the server is operational but the application is offline.
A Known Issue When No External Route is Specified
With connections to an Internet ISP, an external network route should always be specified. This
external route specifies on which interface the network which exists between the Clavister
Security Gateway and the ISP can be found. If only an all-nets route is specified to the ISP's
gateway, route failover may, depending on the connected equipment, not function as expected.
This issue rarely occurs but the reason why it occurs is that ARP queries arriving on a disabled
route will be ignored.
4.2.5. Advanced Settings for Route Failover
The following cOS Core advanced settings are available for route failover:
Iface poll interval
The time in milliseconds between polling for interface failure.
Default: 500
Chapter 4: Routing
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