Abstract: The present invention is directed toward data packet transmission scheduling. Scheduling values, such as priority or other scheduling criteria assigned to data packets, are placed in a scheduling heap data structure. Packets percolate up through the heap by comparing their assigned values in pairs. Operations in the heap may be pipelined so as to provide for high-speed sorting. Thus, a few relatively simple operations can be performed repeatedly to quickly percolate packets up through the heap. Another aspect of the invention provides for fast traversal of the scheduling heap data structure. The hierarchical heap may include a highest level having a single position and each succeeding lower level having twice the number of positions as the preceding level. A binary number may represent each position in the heap. To traverse the heap, the relative movements necessary to move from one position to another may be determined from the binary number. This is useful to quickly and efficiently traverse the heap.

Abstract: A technique for forwarding multi-cast data packets in a communication network. Multi-cast packets are broadcast to every output port of the switch. The packet is thus buffered in each port. Then, all of the output ports, save those that are appropriate output ports for the packet, drop the packet. Accordingly, the output ports that did not drop the packet forward the packet to the network. A control packet that follows the packet may then instruct the ports regarding which ports are to drop the packet and which ports are to forward the packet. This technique has an advantage of efficiently handling multi-cast packets.

Abstract: The present invention is directed toward methods and apparatus for data packet transmission scheduling using a partitioned scheduling heap data structure. The scheduling heap data structure has a plurality of levels for storing scheduling values for data packets according to their relative priorities. A highest level in the heap has a single position and each succeeding lower level has twice the number of positions as the preceding level. The data structure may be adapted to store a plurality of logical heaps within the heap data structure by assigning a highest level of each logical heap to a level in the heap data structure that is lower than the highest level. Thus, a single physical memory may be adapted to store plural logical heaps. This is useful because a single physical memory can be adapted to prioritize packets of various different transmission protocols and speeds.

Abstract: A system and method for providing multiple levels of fault protection in a data communication network. Fault protection criteria for each of a plurality of resources in the network is stored in each of a plurality of nodes of the network. The fault protection criteria includes indicia of a type of fault protection available to the resource. Desired fault protection criteria is determined for a label-switched path between a node of the network that is a source for data and a node of the network that is a destination for the data. A candidate resource in the network for is selected for a communication path between the source and the destination. Whether the candidate resource provides at least the desired level of fault protection is determined from the fault protection criteria. When the candidate resource provides at least the desired level of fault protection, the candidate resource is selected for the communication path.

Abstract: The present invention is directed toward methods and apparatus for packet transmission scheduling in a data communication network. In one aspect, received data packets are assigned to an appropriate one of a plurality of scheduling heap data structures. Each scheduling heap data structure is percolated to identify a most eligible data packet in each heap data structure. A highest-priority one of the most-eligible data packets is identifying by prioritizing among the most-eligible data packets. This is useful because the scheduling tasks may be distributed among the hierarchy of schedulers to efficiently handle data packet scheduling. Another aspect provides a technique for combining priority schemes, such as strict priority and weighted fair queuing. This is useful because packets may have equal priorities or no priorities, such as in the case of certain legacy equipment.

Abstract: The present invention is directed toward data packet transmission scheduling. Scheduling values, such as priority or other scheduling criteria assigned to data packets, are placed in a scheduling heap data structure. Packets percolate up through the heap by comparing their assigned values in pairs. Operations in the heap may be pipelined so as to provide for high-speed sorting. Thus, a few relatively simple operations can be performed repeatedly to quickly percolate packets up through the heap. Another aspect of the invention provides for fast traversal of the scheduling heap data structure. The hierarchical heap may include a highest level having a single position and each succeeding lower level having twice the number of positions as the preceding level. A binary number may represent each position in the heap. To traverse the heap, the relative movements necessary to move from one position to another may be determined from the binary number. This is useful to quickly and efficiently traverse the heap.

Abstract: The present invention is directed toward methods and apparatus for scheduling packet transmission based on anticipated arrival times of the data packets. Arrival times for data packets may be determined relative to a system clock value. Because the system clock is expressed by a finite number of bits, the clock rolls over to all zeros after it reaches its maximum value. Thus, some of the arrival times may be anticipated to occur after the system clock recycles and a comparison of the magnitude of arrival times would not always indicate which is earlier in time. Since packets are limited in length, however, the range of arrival times is bounded. By determining whether the difference between arrival times exceeds the maximum range of arrival times, it can be determined that the result of a comparison of magnitudes yields a wrong result. By knowing that the result is wrong, it can then be reversed to correctly indicate which arrival time occurs first.

Abstract: The present invention is directed toward methods and apparatus for data packet transmission scheduling using a partitioned scheduling heap data structure. The scheduling heap data structure has a plurality of levels for storing scheduling values for data packets according to their relative priorities. A highest level in the heap has a single position and each succeeding lower level has twice the number of positions as the preceding level. The data structure may be adapted to store a plurality of logical heaps within the heap data structure by assigning a highest level of each logical heap to a level in the heap data structure that is lower than the highest level. Thus, a single physical memory may be adapted to store plural logical heaps. This is useful because a single physical memory can be adapted to prioritize packets of various different transmission protocols and speeds.

Abstract: A system and method for fault notification in a data communication network. In accordance with the invention, notification of each fault occurring in the network is quickly and efficiently propagated throughout the network. In response, appropriate action can be taken to recover from the fault. Possible points of failure are identified in the network. Indicia of each identified possible point of failure is formed. The indicia of the identified possible points of failure are propagated within the network. The indicia of the identified possible points of failure are stored in network nodes. Whether a fault has occurred in the network is determined. When a fault has occurred, a fault notification is propagated by at least one of the network nodes that detects the fault to its neighboring network nodes. Propagation of the fault notification may include sending the fault notification by a label switched packet.

Abstract: A system and method for the fast re-routing of data in a data communication network. A protection label path is formed between a base node and an end node wherein the protection path avoids an intermediate node between the base node and the end node. Availability of protection provided by the protection path is advertised within the network. A protected path is formed for communicating data, the protected path passing through the intermediate node. When a fault is detected in the network, the fault is avoided by using the protection path for communicating data. Thus, alternate paths are defined for bypassing entire network nodes. As such, the protection paths allow data to be re-routed so as to avoid failed network nodes as well as failed network links.

Abstract: A quality of service technique for a data communication network. Using a combination of Time Division Multiplexing (TDM) and packet switching, the system is configured to guarantee a predefined bandwidth for a client, which, in turn, helps manage delay and jitter in the data transmission. An ingress processor operates as a bandwidth filter, transmitting packet bursts to distribution channels for queuing in a queuing engine. The queuing engine holds the data packets for subsequent scheduled transmission over the network, which is governed by predetermined priorities. These priorities may be established by several factors including pre-allocated bandwidth, system conditions and other factors. A scheduler then transmits the data received by the queuing engine by a self-clocked fair queuing method.

Abstract: An address learning technique in a data communication network. A packet may be received by the network system when the ingress equipment does not yet have information to lookup the appropriate path for the packet based upon its destination media access control (MAC) address. The packet may then be broadcast or multicast to all possible or probable destinations for the packet. Each such destination adds an entry to its lookup table using the source MAC address and an identification of the path by which it received the packet. Then, when one of those destinations (acting as ingress equipment) receive a packet intended for that MAC address, it will have the necessary information in its lookup table to send the packet along the appropriate path. Thus, table entries are formed and stored in the remote destinations rather than in the ingress equipment.

Abstract: A technique for forwarding multi-cast data packets in a communication network. Multi-cast packets are broadcast to every output port of the switch. The packet is thus buffered in each port. Then, all of the output ports, save those that are appropriate output ports for the packet, drop the packet. Accordingly, the output ports that did not drop the packet forward the packet to the network. A control packet that follows the packet may then instruct the ports regarding which ports are to drop the packet and which ports are to forward the packet. This technique has an advantage of efficiently handling multi-cast packets.

Abstract: A non-blocking virtual switch architecture for a data communication network. The switch includes a plurality of input ports and output ports. Each input port may be connected to each output port by a directly connected network or by a mesh network. Thus, data packets may traverse the switch simultaneously with other packets. At each output port, buffer space is dedicated for queuing packets received from each of the input ports. An arbitration scheme is utilized to forward data from the buffers to the network. Accordingly, the use of a crossbar array, and associated traffic bottlenecks, are avoided. Rather, the system advantageously provides separate buffer space at each output port for every input port.

Abstract: A metro switch and method for transporting data configured according to multiple different formats. In one aspect, a network system and method that provides for point-to-point communication of data of various different formats such as ATM, frame relay, PPP, Ethernet, etc. Accordingly, the invention may interface disparate network devices, such as private networks and other entities that operate according to various different protocols and that use various different media. At ingress points to the system, the data is received from data sources and configured according to a universal format. This allows data from origins that use different data formats and/or transmission media to be mixed and transported onto the same media. The data is then transported to one or more destinations using this format. At egress points of the system, the data is reconverted to its original format for use at its destination.

Abstract: A technique for time division multiplex (TDM) forwarding of data streams. The system uses a common switch fabric resource for TDM and packet switching. In operation, large packets or data streams are divided into smaller portions upon entering a switch. Each portion is assigned a high priority for transmission and a tracking header for tracking it through the switch. Prior to exiting the switch, the portions are reassembled into the data stream. Thus, the smaller portions are passed using a “store-and-forward” technique. Because the portions are each assigned a high priority, the data stream is effectively “cut-through” the switch. That is, the switch may still be receiving later portions of the stream while the switch is forwarding earlier portions of the stream. This technique of providing “cut-through” using a store-and-forward switch mechanism reduces transmission delay and buffer over-runs that otherwise would occur in transmitting large packets or data streams.