Cisco Technology, Inc.

James D Muchow

Mark Alan Bakke

Craig A Johnson

David P Thompson

Timothy J Kuik

Stephen P De Groote

Clayton Stuart Haapala

Donald W Teske

A node (, FIG.), within a networked computer system (), is capable of supporting communications with other nodes relating to operating multiple application instances in a master-slave configuration. Each node periodically generates and sends (, FIG.) a Heartbeat message (FIG.) that indicates the operational status for one or more application instances being managed by the node. When a node receives a Heartbeat message from a remote node, it evaluates (FIG.) the Heartbeat information for each application instance reported in the message, and takes any appropriate actions. The node also determines (, FIG.) whether new configuration information should be obtained for each of the application instances the node is managing, and requests (, FIG.) that new configuration information, when necessary.

Method and apparatus for exchanging heartbeat messages and configuration information between nodes operating in a master-slave configuration

A node (, FIG.), within a networked computer system (), is capable of supporting communications with other nodes relating to operating multiple application instances in a master-slave configuration. A node can be designated as a permanent master for an application instance, meaning that the node will enter the master state (, FIG.) for the application instance whether or not another master exists on the network. A node also can be designated as a preferred slave. A preferred slave initializes (, FIG.) its election timer that is below the election timers selected by other slaves, which causes the preferred slave to call an election before any other slave, and increases the likelihood that the preferred slave will become master if a failover occurs. In addition, a master can specifically resign (, FIG.) to a preferred slave.

Method and apparatus for configuring nodes as masters or slaves

A system and method for accessing Storage Area Networks over an IP network. A SCSI request is generated and encapsulated in one or more IP packets. The encapsulated SCSI request is routed over an IP network and received by a storage router. The storage router extracts the SCSI request from the one or more IP packets and routes the extracted SCSI request through a virtual SCSI router to the storage area network.

SCSI-based storage area network having a SCSI router that routes traffic between SCSI and IP networks

A node (, FIG.), within a networked computer system (), is capable of supporting communications with other nodes relating to operating multiple application instances in a master-slave configuration. The node initiates (, FIG.) and maintains (FIGS.) a state diagram (FIG.) for each application instance currently running in the master-slave configuration on the node or the other nodes. In addition, the node listens for new application instances that are discovered on the node or on the other nodes. The nodes can be interconnected using multiple networks (, FIG.), and redundant messages received by the node can be ignored (FIG.), if those redundant messages would adversely affect maintenance of the state diagram for an application instance. When a node determines that it should no longer operate as a master for an application instance, the node can initiate a resignation process (FIG.), during which another node will attempt to become the master for the application instance.

Method and apparatus for supporting communications between nodes operating in a master-slave configuration

A node, within a networked computer system, is capable of supporting communications with other nodes relating to operating multiple application instances in a master-slave configuration. Each node periodically generates and sends a Heartbeat message that indicates the operational status and configuration information for one or more application instances being managed by the node. When a node receives a Heartbeat message from a remote node, it determines whether new configuration information should be obtained for each of the application instances the node is managing, and establishes a connection with a remote node that can access the new configuration information. The connection is an HTTP connection, in one embodiment. The node then requests and receives that new configuration information from the remote node. In one embodiment, the new configuration information is received in an XML format.

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Zimmerman, MN, United States of America

James D Muchow