Fujitsu Network Communications, Inc.

Fujitsu Corporation

Other

Telica, Inc.

Thomas A Manning

Stephen A Caldara

Stephen A Hauser

Raymond L Strouble

Robert B McClure

David N Peck

Matthias L Colsman

Richard G Bubenik

Douglas H Hunt

Alan D Sherman

Stephen R Veit

Michael E Gaddis

Sean Garcen

Robert H Constantin

David E Hammond

James M Meredith

Emily Manning

Andrew Michal

Peter Hutzli

Edward N Kittlitz

Salma Abu-Ayyash

Pair of socks for double amputees

Mirror cover with logo

A system for indicating and determining a master unit from a plurality of logic units is described. The system includes a first logic unit configured to output a first obey signal and receive a first input signal, and a second logic unit configured to output a second obey signal and receive a second input signal. At least one of the first obey signal and the second obey signal is clocked, and a phase relationship of the second obey signal relative to the first obey signal is controllable by the first and second input signals. The system also includes a mastership determination logic unit configured to monitor the first and second obey signals. The mastership determination logic unit is configured to indicate that the first logic unit is the master unit when only the first obey signal is being clocked and to indicate that the second logic unit is the master unit when only the second obey signal is being clocked. The mastership determination logic unit is also configured to indicate that the first logic unit is the master unit when the first and second signals are being clocked in-phase and to indicate that the second logic unit is the master unit when the first and second signals are being clocked out-of-phase. A method of similar features is also describe.

Fault tolerant mastership system and method

A system for allocating bandwidth in a network element. The system determines whether a bandwidth allocation request is associated with a delay sensitive connection type. If so, the system selects a bandwidth allocation algorithm from a first set of bandwidth allocation algorithms. Otherwise, the system selects a bandwidth allocation algorithm from a second set of bandwidth allocation algorithms. The size of the bandwidth allocation request may be examined when selecting which bandwidth allocation algorithm to use. The system may round up the size of the bandwidth allocation request to a predetermined value. The selected bandwidth allocation algorithm may reserve slots in a bandwidth allocation table. Reserved slots that are equally spaced in the bandwidth allocation table avoid undue delays in servicing an associated connection. A binary tree representation of the table is described, wherein leaves of the binary tree correspond to individual table slots. Specific bandwidth allocation algorithms are described which are advantageously applicable when allocating bandwidth to delay sensitive or relatively delay insensitive connection types.

Crosspoint switch bandwidth allocation management

A system and method for monitoring and maintaining a plurality of modules are described. Each module of the plurality of modules includes at least one link slave device, and a link controller is connected to link slave devices via a plurality of individual serial, bidirectional connections. The link slave devices and the link controller include protocol logic for communication according to a bidirectional protocol. At predefined time segments and predefined periodicity, the link slave devices drive the corresponding bidirectional link to the controller to provider maintenance information to the controller. At other predefined time segments, the controller drives the bidirectional link to issue commands to the link slave devices. The link slave devices and the link controller include protocol logic for communicating according to a protocol in which all slave devices communicate to the link controller at substantially the same period of time so that the latency for collecting information from the slave devices is independent of the number of such devices.

Maintenance link system and method

An Asynchronous Transfer Mode switch and method which facilitate priority arbitration of point-to-point and point-to-multipoint transmission are disclosed. To execute point-to-multipoint operation a bandwidth arbiter maintains a first list of connections and bit vectors indicating designated destination ports. The list maintained by the bandwidth arbiter is then compared to an unassigned output port bit vector to determine matches therebetween at which point-to-multipoint transmission may be made by utilizing instantaneously unused bandwidth within the switch. To execute point-to-point operation each input port maintains a list of connections associated with each output port, and those lists are used in conjunction with output port request information per input port in the bandwidth arbiter to match requests to the unassigned output port bit vector. The bandwidth arbiter may also assign priority to connections in the list.

Priority arbitration for point-to-point and multipoint transmission

Each switch along a call setup path in a network decides whether the call request should be upgraded from a non-flow-controlled service type to a flow-controlled service type. Each switch bases the decision on whether a boolean variable for the calling subscriber that appears in a management information base (MIB) is set to a value indicating that the subscriber is entitled to the upgrade. In addition, the upgrade is performed only if an interface on the route to the called party on which the call setup request is to be forwarded supports flow-controlled connections. When the call is to be upgraded, the switch replaces the service type indicator in the setup message with a value indicating a flow-controlled service type, and forwards the setup message toward the called subscriber. If the MIB variable is set to a value indicating that the upgrade is not to be performed, it is still possible for a subscriber to request flow-controlled service directly, by indicating this service type in the original call setup message. Each switch also makes a call downgrade decision. When a call setup message is received requesting flow-controlled service but destined for an interface that does not support flow-controlled operation, the switch replaces the service type indicator in the outgoing setup message with a value indicating a non-flow-controlled service type.

Distributed control of service category request mapping

Network interface logic includes first logic executing a credit-based flow-control protocol (e.g., Quantum Flow Control or QFC) and second logic executing a rate-based flow control protocol (e.g. Explicit Rate or ER). The second logic transfers data cells between a network link and the first logic and inserts and extracts forward (FRM) and backward (BRM) flow-control/resource management (RM) cells. The second logic further (i) obtains cell buffer utilization information from the first logic, (ii) supplies transmission credits to the first logic based on rate information in BRM cells, (iii) induces the first logic to emit &ldquo;dummy&rdquo; RM cells when an RM cell is to be transmitted, and (iv) converts the dummy cells to either FRM or DRM cells for forwarding on the link. Rate information in the transmitted RM cells is calculated from the buffer utilization information and rate information in extracted BRM cells.

Network switch supporting rate-based and credit-based flow control mechanisms on a link-by-link basis

An asynchronous transfer mode (ATM) based service consolidation switch ( ) includes an input/output module ( ) having a to-switch port (TSPP) processor ( ) and a from-switch port processor (FSPP) ( ). The TSPP ( ) and the FSPP ( ) communicate with a bandwidth arbiter ( ), multipoint topology controllers ( ), and a data crossbar ( ) on a switch control module ( ). The TSPP ( ) receives traffic over links for conversion into an internal cell format. Internal cells are buffered until allowed to transfer to an appropriate FSPP ( ). Multipoint topology controllers ( ) performs translations for internal switch flow control through interactions between the TSPPs ( ), FSPPs ( ), and the bandwidth arbiter ( ). The bandwidth arbiter ( ) performs appropriate bandwidth arbitration to allow internal cells to flow from TSPPs ( ) to FSPPs ( ) over the data crossbar ( ).

Asynchronous transfer mode based service consolidation switch

A method and apparatus for providing buffer state accounting at a link level, otherwise known as link flow control, in addition to flow control at the virtual connection level. Link flow control enables receiver cell buffer sharing while maintaining per-connection bandwidth with lossless cell transmission. High link level update frequency is enabled without a significant sacrifice in overall link forward bandwidth. A higher and thus more efficient utilization of receiver cell buffers is achieved.

Method and apparatus for providing buffer state flow control at the link level in addition to flow control on a per-connection basis

A system (,) is provided for identifying a processing port (,) and a link (,) at which a cell (,) is received. The system (,) includes a logical link table (,) having a plurality of logical link entries (,). Each logical link entry (,), which corresponds to a particular link (,) of a processing port (,) associated with the logical link table (,), specifies a numerical value. The processing port (,) may receive the cell (,) at one of a plurality of links (,). The processing port (,) can convert the cell (,) by replacing a numerical value of an identification field, such as a virtual channel identification field (,), of the cell (,) with the numerical value specified by the logical link entry (,) corresponding to the link (,) at which the cell (,) is received. A switch control module (,), which is connected to the processing port (,), may receive the converted cell (,). The switch control module (,) can identify the link (,) and the processing port (,) at which the cell (,) corresponding to the converted cell (,) was received by referencing a reverse mapping table (,) using the numerical value of the logical link entry (,) in the converted cell (,).

Port and link identification

A system for allocating resources at network elements along a path through a communications network. Resources are allocated at a network element along the path in response to a connection request message. The delay budget is the minimum of a calculated cell transfer delay and a calculated cell delay variation. The calculated cell transfer delay is determined by finding a difference between a target end to end cell delay and an accumulated cell delay, and then dividing that difference by a number of network elements remaining in the path between the network element and the end of the path. To determine the calculated cell delay variation, the network element first finds a difference between the Max CDV QoS parameter and the sum of the accumulated cell delay variation and the switching delay for the network element. The calculated cell delay variation is then equal to that difference divided by the number of network elements remaining in the path between the network element and the end of the path. The target end to end cell delay is for example determined by the first network element in the path as equal to the Max CTD QoS parameter minus the end to end link propagation delay for the path and the link propagation delay for the incoming link to the first network element over which the message was received. The first network element generates and forwards a modified connection request message including the determined target end to end cell delay value, as well as a designated transit list indicating each network element in the prospective path, and including a current network element pointer.

Network element delay allocation for efficient use of network resources

A mechanism enabling plural queues in a downstream telecommunications network element to be treated as a single, joint queue for purposes of connection-level flow control. A pointer in at least one queue descriptor points to a queue descriptor in which is maintained a set of shared, joint counters. Other flow control elements are maintained individually with respect to each queue descriptor. This mechanism enables flow control elements associated with a single transmitter queue to flow control plural connections terminating in plural queues associated with a single receiver processor.

Joint flow control mechanism in a telecommunications network

An Asynchronous Transfer Mode switch and method which facilitate point-to-multipoint transmission are disclosed. Each input port within the switch includes a switch allocation table ('SAT') which manages bandwidth allocation and delay. Each SAT includes a plurality of sequentially ordered cell time slots, a subqueue and a synchronized pointer which is directed to one of the slots such that at any given point in time each of the pointers is directed to the same slot location in the respective SAT with which the pointer is associated. To execute point-to-multipoint operation where output port conflicts are present the switch transmits copies of the cell to the output ports at different points in time. More particularly, the switch transmits copies of the cell to available output ports, and tracks such transmission for managing future transmission to unserviced output ports. To track transmission the switch includes a map and scoreboard. The subqueues are used to index into a table and may be associated with one or more output ports. The map indicates which subqueues, and hence which output ports, are initially eligible to receive a copy of the cell. The scoreboard indicates which subqueues, and hence which output ports, have received a copy of the cell. Tracking is realized by updating the scoreboard when copies of cells are transmitted. Copies of the cell are not sent to already serviced output ports. When each designated subqueue has been service, and hence each associated output port has been serviced, the cell is dequeued.

Growing community of inventors

Northboro, MA, United States of America

Thomas A Manning