Abstract: A method for transferring thermal energy from an electronic card in a card shelf includes providing a divider configured for high absorption of thermal energy adjacent to an electronic card in the card shelf. Thermal energy generated by the electronic card is absorbed in the divider and transferred away from the electronic card via the divider. The divider may include a roughened surface texture, surface coating, or other dull surface exhibiting high thermal energy absorption properties. The divider may convectively transfer the thermal energy away from the electronic card. The divider may also be thermally coupled to a heatsink to conductively transfer the thermal energy away from the electronic card.

Abstract: An advanced SONET add/drop multiplexer capable of supporting packet over SONET and multiprotocol label switching. The add/drop multiplexer is capable of adding and/or dropping both STM and packet traffic, such as Internet Protocol traffic. This SONET add/drop multiplexer allows Internet Protocol streams which are added or dropped at different nodes to be carried over the same SONET path in a network, thereby greatly saving bandwidth.

Abstract: A method for protecting virtual channel connection (VCC) traffic in a telecommunications system includes receiving a virtual path connection (VPC) at a destination node. The virtual path connection (VPC) is received on each of a working transmission link and a protection transmission link. The virtual path connection (VPC) includes a plurality of virtual channel connections (VCCs) A protection switching status is received for the working and protection transmission links. The virtual channel connections (VCCs) are selected from the working and protection transmission links for processing by selecting the virtual path connection (VPC) from one of the working and protection links based on the protection switching status for at least one of the working and protection transmission links.

Abstract: A communications device and method for effectively managing bandwidth within a telecommunications network carrying both time division multiplexed signals as well as data signals. The communications device having dialable TDM/cell and/or packet-based bandwidth management capability so that a network operator can select to manage bandwidth for any particular signal on in STS, VT, or cell or packet basis.

Abstract: A card shelf includes a backplane and a plurality of slots each configured to receive an electronic card. An electronic card disposed in one of the slots has a back including a connector adapted to engage the backplane and a front including an angled receptor adapted to engage a cable with a reduced projection from the electronic card. A cable holder is aligned with the slot containing the electronic card. The cable holder is operable to receive the cable from the angled receptor. A cable trough is operable to receive the cable from the cable holder and route the cable away from the card shelf. The cable holder may include a plurality of cable receivers aligned with each slot for an electronic card in the card shelf. Each cable receiver may include a portion for receiving one or more cables from each electronic card and a portion for retaining the cables within the cable receiver.

Abstract: In accordance with the present invention a method and apparatus are disclosed in which each data stream of a plurality of data streams is assigned to a queue and each queue is allocated a predetermined maximum numbers of buffers. Once the queue has exhausted its supply of buffers, the data from the corresponding data stream is discarded until buffers are refreshed thereby allowing the remaining data streams to operate in a normal fashion. Accordingly, excessive buffer usage by an individual data stream is prevented, as well as excessive demand of other related system resources such as CPU time. The data stream which has had its data discarded will begin having its incoming data processed upon the next refresh operation providing the queue associated with that data stream has had additional buffers allocated. The discarded data is lost and is not recovered. The refresh operation is performed in a manner that provides prioritization of the queues and a high degree of fairness within each priority level.

Abstract: A SONET interface line unit which includes an interface to a SONET ring, an STM switch fabric, and STM synchronization function within a single module. The line unit includes an optical interface for communicating SONET traffic with a SONET ring, an ATM interface for communicating ATM traffic with an ATM switch fabric unit, and two or more service unit interfaces for communicating with service units having service interfaces to a service side of a network element. The service unit interfaces operate using the STM protocol. The line unit further includes forwarding logic for extracting ATM traffic and STM traffic from the composite traffic received from the SONET ring. The line unit further provides synchronization signals to other units within the network element, derived from a selected timing reference signal. An extended synchronization module is used to interface to a larger number of timing references within the device.

Abstract: A hybrid protection circuit (10) operatively couples a plurality of communication paths in ingress cables (12) to a plurality of communication paths in egress cables (13). A line selector (31) effects protection switching of communication paths in one cable relative to communication paths in another cable, producing an output which is supplied to each of two switching sections (36, 37). The switching sections respectively effect switching according to a synchronous transport mode (STM) protocol, and an asynchronous transport mode (ATM) protocol. A multiplexer (57) selectively combines signals from the two switching sections, and supplies the result to a bridge circuit (61), which performs protection switching of these signals relative to communication paths in the respective egress cables (13).

Abstract: A system for downloading a software image to a SONET network element which eliminates the need for a separate overhead channel for this purpose. The system conveys the software image using the File Transfer Protocol (FTP) over the Transmission Control Protocol (TCP), over the Internet Protocol (IP), using ATM. The disclosed system enables ATM cells carrying the software image to be received over a SONET ring connected to the device. The disclosed system uses permanent virtual circuits (PVCs) between network elements over which the software image may be transported. In a first embodiment, the PVCs form a star of logical connections with remote network elements to which software image files may be downloaded from a “gateway” network element. The gateway network element is a network element communicative with a central management station, which provides data to be downloaded to the remote network elements.

Abstract: A system for temporarily storing and dequeuing received data units including searching a prioritized queue list for a highest priority queue having a head entry associated with a received data unit which is part of the guaranteed bandwidth of the connection on which it was received, and for which there are sufficient transmission credits available, based on a flow control mode associated with the data unit. If no such guaranteed bandwidth data unit is found, the system dequeues a highest priority queue having a head entry associated with an available bandwidth data unit, for which there are sufficient transmission credits available to begin transmission based on a flow control mode associated with the data unit. If no such available bandwidth data unit is found, then no data unit is dequeued during that traversal of the queue list.

Abstract: 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.

Abstract: Permission based flow control is implemented in a computer network having at least a downstream, intermediate and upstream network device by receiving credits at the intermediate network device from the downstream network device and granting credits from the intermediate network device to the upstream network device based at least in part upon the credits received at the intermediate network device from the downstream network device. Credit chaining as described above is employed to permit the granting of the right to transmit downstream to be predicated upon buffer availability downstream of the next downstream network device. Via the use of credit chaining, high utilization of network resources is achieved with minimal loss of data traffic.

Abstract: A system (10) is provided for identifying a processing port (12) and a link (22) at which a cell (24) is received. The system (10) includes a logical link table (14) having a plurality of logical link entries (30). Each logical link entry (30), which corresponds to a particular link (22) of a processing port (12) associated with the logical link table (14), specifies a numerical value. The processing port (12) may receive the cell (24) at one of a plurality of links (22). The processing port (12) can convert the cell (24) by replacing a numerical value of an identification field, such as a virtual channel identification field (28), of the cell (24) with the numerical value specified by the logical link entry (30) corresponding to the link (22) at which the cell (24) is received. A switch control module (18), which is connected to the processing port (12), may receive the converted cell (38).

Abstract: A system and method for performing event-based rate policing using varying window start times. Rate policing overhead, including counter and timer monitoring and resetting, is performed only as needed and in response to actual received traffic on each connection. As the last bit of a data unit is received from an external network, an “event time stamp” is generated and associated with the data unit, for example as part of an internal header or trailer attached to the data unit. To determine if a rate policing window was active when the frame was received, the event time stamp is compared with a sum of a window start time and a window period value stored in association with the connection on which the data unit was received. If the associated event time stamp indicates a time prior to the sum of the associated window start time and window period, then a rate policing window is determined to have been active when the frame was received.

Abstract: An optical fiber connection unit has a circuit board with a hole formed therein, oval shaped inner and outer channels separated by an oval shaped separating wall, extension supports and a standoff. The oval shaped inner channel has a radius at least as large as a minimum bend radius of a polymeric optical fiber. The oval shaped outer channel follows the inner channel, but has a larger radius than the inner channel. The oval shaped separating wall has a plurality of openings formed therein where passage between the inner and outer channels is possible. The extension supports extend between the opposing sides of the inner channel. The extension supports meet at an intersection thereof, and a connection hole is formed at the intersection where the extension supports meet. The standoff is removably secured to both the hole in the circuit board and the connection hole formed at the intersection of the extension supports.

Abstract: A constant phase crossbar switch system which avoids phase discontinuities at the outputs of the crossbar switch. The crossbar switch system includes input logic, a crossbar switch, output logic and a phase locked loop. The phase locked loop is used to generate a high speed internal clock from a system clock. High speed serial data streams transmitted at the internal clock frequency are received from corresponding transmitters and are coupled to the input logic. The input logic generates multiple versions of each serial data stream, one of the versions being undelayed and the other versions delayed by some fraction of a bit time. State machines are employed to selects the version of the serial data stream which results in the data stream data window being generally centered with respect to the high speed internal clock. The selected version of the data stream is employed as the active input to the crossbar switch.

Abstract: 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.

Abstract: Flow shaping is executed at each ATM device in a virtual circuit formed in an ATM network. More particularly, the flow of data units through the virtual circuit is controlled at each ATM switch such that the variable transmission delay remains substantially constant from hop to hop. Flow shaping at each device causes variable transmission delay to remain substantially constant throughout the virtual circuit, thereby allowing formation of an ATM virtual circuit having an arbitrarily large number of ATM switch “hops” without constraints imposed by required playout buffer size. Further, the invention minimizes end-to-end delay.

Abstract: An encoder/decoder is disclosed which is operative to convert an 8 bit value to a ten bit serial run length limited code for transmission over a serial data link. The encoding technique maintains DC balance within 2 bits over a single ten bit word and compensates for DC imbalance by inverting selected words in the transmission sequence to correct for a DC imbalance resulting from the transmission of a prior unbalanced word. One or more encoding lookup tables are employed at the encoder to map each byte into a ten bit run length limited code for serialization and transmission over the serial data link. A second decoding lookup table is employed at the decoder to map the received 10 bit run length limited code into the original 8 bit value.

Abstract: A system and method for providing QoS levels to received data units, such as ATM cells and/or Frame Relay Frames. A QoS level associated with a virtual connection is supported through allocation and management of resources used to process data units received over the connection. Resources used to support QoS levels are assigned to groups of connections referred to as “QoS groups”. Resources used to support one group of connections may be isolated from resources supporting other connections. When a connection is established, if a QoS group exists having the QoS level of the new connection, the connection may be added to that QoS group. Similarly, where the QoS levels for multiple connections must be modified, if those connections are within a single QoS group, then modification of the QoS level for that group would advantageously result in modification of the QoS for each virtual connection within the QoS group.