C•CURE 800/8000 Hardware Configuration Guide - Tyco Security ...

Cluster Communications OverviewExample:The master and host send these messages to each other to confirm that theconnection between them is open. If the host does not receive aconnection verification message from the master in a specified amount oftime, the host closes the communications link with the master and waitsfor a connection attempt from the cluster. When the master does notreceive a connection verification message from the host in the specifiedamount of time, it also declares a communications failure for the primarycommunications path and then notifies its cluster members of thecommunications failure. At this time, cluster communications revert tothe secondary communications path.Use the Cluster dialog box in the C•CURE System AdministrationApplication to configure connection verification messages for the master,host, and cluster members. See “Configuring Clusters” on page 2-34 for moreinformation.Establishing a Secondary Communications PathIf a communications failure occurs on the primary communications path,communications can be re-established via the cluster’s secondarycommunications path. The secondary communications path can be one of thefollowing connections:• A second network connection between the master and the host.• A network connection between another controller in the cluster - thealternate master - and the host.The configuration of the secondary communications path (alternate master ora secondary connection from the master) determines how controllers reestablishcluster communications when the primary path fails. See“Maintaining Cluster Communications” on page 2-32 for more information.While communicating via the secondary path, the cluster attempts to reestablishcommunications with the host on the primary communications path.When a connection is re-established on the primary path, communicationsrevert to the primary path and the communications link on the secondarypath is closed.2–30 C•CURE 800/8000 Hardware Configuration Guide