International Business Machines Corporation

Prabandham M Gopal

Marcia Lambert Peters

Marc Adam Kaplan

Michael James Ward

Joshua S Auerbach

John E Drake, Jr

Elizabeth A Hervatic

Shay Kutten

Chee-Seng Chow

Ray W Boyles

Michael F Gierlach

Gary M Vacek

Robert Sultan

A multinode, multicast communications network has a distributed control for the creation, administration and operational mode selection operative in each of the nodes of the network. Each node is provided with a Set Manager for controlling either creation of, administration or access to a set of users to whom a multicast is to be directed. The Set Manager maintains a record of the local membership of all users associated with the node in which the Set Manager resides. A given Set Manager for each designated set of users is assigned the task of being the Set Leader to maintain membership information about the entire set of users in the multicast group. One of the Set Managers in the communications network is designated to be the Registrar which maintains a list of all the Set Leaders in the network. The Registrar insures that there is one and only one Set Leader for each set of users, answers inquiries about the membership of the sets and directs inquiries to appropriate Set Leaders if necessary. All of the set creation, administration and control functions can therefore be carried out by any node of the system and provision is made to assume the function at a new node when failure or partition in the network occurs.

Distributed management communications network

A computer network in which resources are dynamically located through the use of LOCATE requests includes multiple cache server nodes, network nodes which have an additional obligation to build and maintain large caches of directory entries. Cache server nodes play a key role in the LOCATE process and can prevent redundant network-wide broadcasts of LOCATE requests. Where an origin cache server node receives a request from a served node, the cache server node searches its local directories first, then forwards the request to alternate cache server nodes if necessary. If the necessary information isn't found locally or in alternate cache server nodes, the LOCATE request is then broadcast to all network nodes in the network. If the broadcast results are negative, the request is forwarded to selected gateway nodes to permit the search to continue in adjacent networks.

Locating resources in computer networks having cache server nodes

In a multicast network communication system, administration of the communication path making up the multicast tree itself has been separated from control and administration of the network. Creation of a multicast distribution tree and control over the membership thereof, is separately controlled independently from the creation and use of the tree transmission path used to communicate among the members of a multicast set. Transmission distribution trees are set up when a transmission request is received and the properties of the transmission path that is required are known. Transmission paths are created and controlled by all nodes in the communications system, each node having necessary control code and processors for responding to requests from set members to transmit a message to groups of users by creating and activating the necessary tree communication path distribution linkages. A distribution tree is created by the Tree Leader by generating a tree address using a random number generator. A tree address correlator is generated utilizing network and node identifiers unique for the network, and a list of subnodes or users connected for each member of the multicast tree set is generated. Using this information, a tree distribution path is computed to cover all of the subnodes required and a tree set up request message is sent by the Tree Leader along a computed path to each involved subnode. Each subnode returns a message indicating whether the tree address is already in use or is available for use. Successfully negotiated tree addresses are marked at the path link initiation and termination points at each node through the network.

Multicast communication tree creation and control method and apparatus

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Wayne, NJ, United States of America

Prabandham M Gopal