Motorola 68P02958C00-B - Manual (Page 238)

HealthCheck Mechanism
6-3
IP Gateway through the same link the Ping arrived. Unless being pinged, the RTU
HealthCheck mechanism will not initiate any communication.
Disabled HealthCheck
When HealthCheck is disabled in the IP Gateway, the IP Gateway will assume that all sites
registered in the site table are reachable. However – since SNMP proxy operation relies on
HealthCheck, disabling this mechanism will disable any SNMP proxy operation (MCPS).
When HealthCheck is disabled in the RTU, the RTU MDLC stack will not allow the incoming
of any HealthCheck messages. Instead, an automatic response indicating that HealthCheck
application is blocked will be communicated back to the originator of an incoming ping frame.
The IP Gateway HealthCheck, though, is capable of handling such cases by assuming the link
is OK if such a response is received. However, the indications received from the HealthCheck
mechanism may not be accurate, as the path the response traveled through cannot be
determined.
HealthCheck Setup
Setting up the Site Table
The IP Gateway site-table should contain all the sites upon which the HealthCheck is
requested to operate. Each site is associated with two links, one primary and one secondary.
Additionally, each link is given a time parameter – Link validity interval. For each link, the
HealthCheck mechanism uses the Link validity interval for calculating the time basis for the
Ping-Pong mechanism to operate. Further – this parameter also determines the maximum time
to wait for a Pong to arrive back at the IP Gateway before declaring a link to be in a failure
condition. . .
When defining primary and secondary links, one should pay attention to the following:
•
Primary and secondary links may be identical. In this case, the HealthCheck mechanism
will assume the site possesses only one link and thus will not ping the same site twice.
•
Primary and secondary links may not be identical. However in this case – the two paths to
the site (one through each link) should not overlap any part of the route. If two different
paths to the same RTU do indeed overlap part of the route, the indications received from
the HealthCheck mechanism may not be accurate.
For more information, see the description of the IP Gateway Toolbox Site Table utility above.
Site Configuration
The IP Gateway HealthCheck mechanism is activated through IP Gateway Toolbox Site
Configuration utility. In order to activate it,
1. Run the Site Configuration utility from the IP Gateway Toolbox.
2. Click on the Advanced tab in the workspace bar.
3. Open the Message Oriented Service advanced parameters screen.