Abstract: In a packet communications network, the addition or deletion of a connection to the network by a user is governed by a link traffic metric which represents the effective capacity of each link in the network which participates in the packet connection route. The link metric is calculated in real-time and updated by simple vector addition or subtraction. Moreover, this link metric is also used to calculate leaky bucket parameters which govern the access of packets to the network once the connection is set up. A packet network using these link metrics and metric generation techniques provides maximum packet throughput while, at the same time, preserving grade of service guarantees.

Abstract: A packet communications network relies on a few simple parameters to characterize the wide variety of traffic offered to that network, such as peak bit rate, mean bit rate and average packet burst length. A better representation of many types of traffic relies on an equivalent burst length which produces the same loss probability distribution, but assumes that the distribution is uncorrelated and exponential. Access control and bandwidth management based on such an equivalent burst length produces improved decisions due to the more accurate representation of the actual traffic distribution.

Abstract: A packet communications system utilizes a route determining mechanism by identifying principal paths between the source and the destination in the system. Principal paths are minimum hop count paths with a transmission delay less than a specified threshold. Principal path links are accepted as legs of the optimum path, if feasible, i.e., if the resulting load on the link is less than a specified principal threshold. Secondary links are accepted only if the resulting load on the link is less than a specified secondary threshold, where the secondary threshold is less than the principal threshold. All paths must also have a transmission delay less than a specified threshold. Each request for a route includes the source node, the destination node, the load required, the maximum transmission delay and, if desired, the quality of service parameters which all of the legs of the route must satisfy.

Abstract: This invention describes a method of transmitting data through a passive central switching fabric, where data can be transmitted from any input port of the fabric to any output port of the fabric. The switching fabric has N multiplexors and N demultiplexors. The input ports of the demultiplexors are the input ports of the fabric, while the output ports of the multiplexors are the output ports of the fabric. The outputs of each demultiplexor lie in a horizontal plane, while the inputs of each multiplexor lie in a vertical plane. The outputs of the demultiplexors in the horizontal planes are butted against the inputs of the multiplexors so as to establish optical contact between the outputs of the demultiplexors and the inputs of the multiplexors. Modulated wavelengths are then demultiplexed and mutliplexed in such a fashion so as to allow data from any input port of the switching fabric to be transmitted to any output port of the switching fabric merely by modulating a corresponding one of N wavelengths.

Abstract: The present invention identifies boundaries of data packets within a serial data stream and transfers data belonging to these packets to an external device for processing or storage. Identification is accomplished at relatively high speed by parallel processing techniques using a state machine. Data may be transmitted through separate channels to a multiple channel link. This link selects one channel at a time for a predetermined period of time, and allows the data stream from the selected channel to be transmitted to the flag detector. Some of the bits in the digital data stream may be part of a flag. The flag detector generates a value corresponding to the number of bits which may correspond to a portion of a flag in the data that has entered the flag detector. Additional data from the digital data stream entering the flag detector may include the remaining bits of the flag. If so, then the detector indicates that a flag has been found.

Abstract: In a data communication network the routing of data items from a group of eight source processors to a group of eight destination processors is controlled by code values assigned to each of the data values. The data items to be routed are bit-serial binary signals. These are encoded by the source processor using a pair of code values, one for each value of a bit of the binary signal. The eight source processors each encode eight bit-serial signals using respectively different code tables. The code tables are generated as different permutations of a basic code set. Each code table has the property that any additive combination of encoded values for all of the data items in a group produces a unique sum. The eight encoded values produced by each processor are summed to produce a set of analog channel symbols that are transmitted over an analog channel to a central switch fabric. In the switch fabric, the channel symbols are partially decoded to recover the encoded data values.