摘要:
A management system for local area networks ensures selected levels of quality of service to all transmission requests submitted to the management system. This management system is attached to the network and receives requests from all other stations on the network to reserve facilities for a particular quality of service data stream. An allocator in the management system determines if the requested facilities are available and, if so, reserves these facilities for the requesting station. If the facilities are not available, the request is denied. A hierarchical data base containing all of the current parameters of all of the network resources and all of the currently supported data streams is used to support the allocation process.
摘要:
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.
摘要:
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.
摘要:
A method is disclosed for determining whether to use a preempt/resume protocol or an alternate protocol in transmitting data packets from a local system to a remote system. Each system informs the other whether it supports preempt/resume and provides the sizes of the largest low priority data packets it can send and receive. The local system always elects the alternate protocol unless both support preempt/resume. The local system then selects the lesser of (a) the largest low-priority data packet it can send and (b) the largest low-priority data packet the remote system can receive. Use of prompt/resume is initiated by the local system only where a packet of the selected size would be delayed in reaching the remote system by more than a predetermined interval.
摘要:
Each node in a multinode communication system is provided with programming to act as a Set Manager for a given set of nodes and users. Functions of the Set Manager include operation processes for creating distribution trees for efficient multicast and bandwidth reservation tasks. Because set membership is not necessarily fixed or accurate at the time the distribution tree is created, the Tree Leader task that creates and maintains the trees needs accurate and updated information showing the number of users at the nodes it serves which are participating in the distribution tree. The count of active users at nodes served by the Tree Leader is provided in response to an indicia established at the time the Tree Leader sets up the tree. Each Set Manager at a given node monitors for changes in set membership and link failure and notifies the requesting Tree Leaders for each tree in which it participates whenever changes in the number of users either by joining or leaving the set or link failures occur by direct communication between the Set Managers and the Tree Leaders without requiring intervention of other elements in the system.
摘要:
A method of reconfiguring a multipoint communications channel to reconnect selected nodes after failures occur in the network disclosed. The method for this invention requires that a selected node (leader) participating in the multipoint communication channel act as the coordinator of the re-establishment protocol. The coordinator (leader) monitors the state of network topology to determine failures, recomputes an alternative feasible communication channel path in the case of failure, and generates messages to join new network elements in the multipoint communication channel. By using a novel tree recomputation method that rejoins the disconnected subtrees created by the network failure to the tree containing the coordinator, along with network topology information, the coordinator is able to minimize messaging and preserve the original channel to the maximum possible extent. The invention can be practiced in a network which provides quality-of-service characteristics to multipoint connections, by ensuring that the recomputation of the multipoint communication channel preserves the quality-of-service of the original connection.