3Com Corporation

Meir Morgenstern

David Margulis

Haim Rochberger

Sarit Shani

David Margolis

A method of detecting a signaling congestion situation in a transmitter within a communications switch and for handling and recovering from the congestion. The method functions to (1) monitor the level of the transmit queue for each output port and (2) to monitor the level of the signaling message buffer memory pool for all ports. When the levels of either pass predetermined thresholds, the signaling congestion state is declared. Once the signaling congestion state is declared, the call control or equivalent entity in the communications device stops routing new calls from/towards all ports that are in the signaling congestion state. The call control continues to handle existing calls from/towards ports that are in the signaling congestion state.

Method of detecting and recovering from signaling congestion in an asynchronous transfer mode network

VC multicast implementation scheme utilizing VP tunneling over public ATM VP switched networks utilizing P P and P M connections to provide VC multicast capability to the attached private ATM networks. The border ATM VC switch in each private ATM network is connected to the ATM VP switch in the public ATM network via a physical interface adapted to carry one or more P P VP tunnels. A P P VP tunnel is established from each VC switch to all other VC switches connected to the public ATM network. A dedicated P M VP tunnel is established between the source VC switch to each of the destination VC switches connected to the public ATM network. For each multicast connection to be established, a VPI/VCI value pair is allocated over the dedicated P M VP tunnel used to transmit data associated with all P M calls for all the P P VP tunnels carried by the physical interface.

Virtual channel multicast utilizing virtual path tunneling in asynchronous mode transfer networks

A system comprising a single sender SMS for forwarding multicast traffic is collocated in the same device as the LEC thus creating an optimal distribution path for multicast traffic. This reduces the latency of transmission of multicast traffic from sender to receivers by eliminating the need to transmit cells from the LEC to the SMS via the network and reassemble cells into frames and segment frames into cells. The SMS functions as a private SMS for exclusive use by the LEC alone. The SMS of the present invention enables a LEC to distribute multicast traffic in a very efficient manner. The LEC communicates with the SMS directly via the operating system internal messaging subsystem or equivalent. The multicast traffic is sent on a P M connection from the sending LEC via the SMS to all the receiving LECs interested in listening to a given MMAC. In a first embodiment, the LEC internally has knowledge of the existence of the private SMS and is inhibited from issuing a LE_ARP_REQ to find the SMS. The LES is prevented from assigning an LEC to that SMS. In a second embodiment, address and LEC information is predefined for the SMS and propagated to all the SMSs. The LES is directed to permit only a single LEC to be assigned to a SMS preventing the LES from assigning a LEC other than the registered LEC to that SMS.

Single sender private multicast server for use with LAN emulation in asynchronous transfer mode networks

A method of calculating a complex node representation for logical nodes in a hierarchical peer group in a PNNI based ATM network. The summary information for default spokes, exceptions and bypasses is determined in a way that closely represents the underlying metrics associated with the peer group. A list of all border nodes in the peer group is generated and maintained and a matrix of tables is generated, one table for each metric per each class of service. The table is populated by the best value associated with the corresponding metric for a particular pair of border nodes within a particular class of service. Once the table is populated, each element is placed in a group or bin. The bins are generated by dividing the full range of the metric into a plurality of smaller subgroups or bins. The bin having a count greater than a threshold count is selected and 80% of the worst value for that group is used as the default spoke. If no bin exists having at least a threshold count, the number of bins is reduced by one and a new set of subranges is calculated. The elements of the table are placed in the newly divided bins and a scan is performed once again.

Complex node representation in an asynchronous transfer mode PNNI network

A method of determining an efficient route to a well known address that is particularly applicable to networks that do not have the capability of source routing for calculating routes to specific addresses such as ATM networks based on the IISP protocol. The well known address may represent any entity in the network that provides distributed services (e.g., network server applications) that are to be shared among many nodes and applications on the network, such as LECSs. The method of functions to automatically and dynamically register 'well known' addresses on the ports of each node that implements the invention. This permits applications on the network to route to the destination in the shortest possible path thus utilizing network resources in an efficient manner. If there is more than one location with the well known address, e.g., a redundant LECSs in the network, or more than one route to the location then the optimum location will be the one routed to. An optimum location can be determined using any suitable criteria to determine the optimum route to a LECS such as distance, hop count, cost function, link sum, link capacity, etc.

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Or Yehuda, Israel

Meir Morgenstern