摘要:
In a link-level flow controlled system, a method and apparatus providing the ability to partition a buffer resource among multiple prioritized buffer subsets through definition of at least one threshold, the buffer resource being shared by a plurality of connections. Different category of service levels, in terms of delay bounds, are thus enabled. The presently disclosed link-level flow controlled system provides for zero cell loss. The shared buffer resource is divided among N priority pools, defined by N-1 threshold levels, each priority pool attributable to a respective category of service. Link-level counters and registers, disposed in a transmit element, as well as an indication of priority level associated with each connection, are employed in realizing the shared buffer resource.
摘要:
A communication system comprising a hub slot adapted to receive any one of a plurality of hub cards for receiving and transmitting data cells; a plurality of universal card slots; a plurality of interface cards insertable in any one of the plurality of universal card slots for receiving incoming ones of the data cells containing data and transmitting outgoing ones of the data cells containing data; an add bus having respective data links connected between individual ones of the universal card slots and the hub slot for receiving the outgoing ones of the data cells from the plurality of interface cards and transmitting the outgoing ones of the data cells to the hub slot; a drop bus having a single data link connected between all of the universal card slots and the hub slot for transmitting the incoming ones of the data cells from the hub slot to the plurality of interface cards; and an arrangement within each of the interface cards for filtering the incoming ones of the data cells from the drop bus and thereby routing the data cells to an appropriate one or more of the plurality of interface cards.
摘要:
Methods and apparatus for scheduling cell transmission over a network link by a switch. The switch includes a plurality of queues associated with each link. Lists of queues are maintained for each link. In one embodiment, each link is associated with more than one type of list (with the list type corresponding to a scheduling category) and more than one prioritized list of each type (with the priority of the list corresponding to a quality of service). The scheduling lists are accessed to permit cell transmission from a queue contained therein in a predetermined sequence as a function of scheduling category, priority within a particular scheduling category and whether the bandwidth requirement for the particular scheduling category has been met. With this arrangement, maximum permissible delay requirements for each scheduling category are met.
摘要:
A communication device (10) includes a number of input/output modules (12) coupled to a switch control module (14) using an interconnect (40) and to a redundant switch control module (16) using a redundant interconnect (42). Each interconnect (40) and redundant interconnect (42) includes a control interconnect (44) and a data interconnect (46). The control interconnect (44) establishes control information for transferring a cell in the communication device (10) and the data interconnect (46) performs the cell transfer.
摘要:
A system is disclosed for eliminating cell loss through the use of flow control of both allocated and dynamic bandwidth. When output buffers in the switch become filled to a predetermined threshold level a feedback message is provided to input buffers to prevent transmission of cells from the input buffers to the output buffers. In order to provide connection and traffic type isolation the buffers are grouped into queues and flow control may be implemented on a per queue basis. The feedback message is a digital signal including an ACCEPT/REJECT message and a NO-OP/XOFF message. An XOFF message can be received while transmitting via allocated bandwidth or dynamic bandwidth. In particular, an XOFF (allocated) message may be received with regard to allocated bandwidth and an XOFF (dynamic) message may be received with regard to dynamic bandwidth. When ACCEPT is received by the requesting input queue the cell is transferred to the output queue. When REJECT is received by the requesting queue the cell is not transferred. When XOFF (dynamic) is received by the requesting input queue further requests to transfer to that output queue by the requesting input queue using dynamic bandwidth are halted until receipt of an XON message from that output queue. When XOFF (allocated) is received by the requesting input queue further requests to transfer to that output queue by the requesting input queue using allocated bandwidth are halted until receipt of an XON message from that output queue.
摘要:
An asynchronous transfer mode (ATM) based service consolidation switch (10) includes an input/output module (22) having a to-switch port (TSPP) processor (90) and a from-switch port processor (FSPP) (92). The TSPP (90) and the FSPP (92) communicate with a bandwidth arbiter (114), multipoint topology controllers (116), and a data crossbar (117) on a switch control module (32). The TSPP (90) receives traffic over links for conversion into an internal cell format. Internal cells are buffered until allowed to transfer to an appropriate FSPP (92). Multipoint topology controllers (116) performs translations for internal switch flow control through interactions between the TSPPs (90), FSPPs (92), and the bandwidth arbiter (114). The bandwidth arbiter (114) performs appropriate bandwidth arbitration to allow internal cells to flow from TSPPs (90) to FSPPs (92) over the data crossbar (117).
摘要:
An ATM cell switch has a cell multiplexer connected by a shared bus to a cell demultiplexer. In a first aspect of the invention, writing of cell data in the cell multiplexer is staggered to even out current consumption. In a second aspect, the cell multiplexer has input processors enabling it to receive cell data from input ports with different data rates, and the cell demultiplexer has output processors enabling it to send cell data to output ports with different data rates. In a third aspect, the multiplexing sequence on the shared bus is periodically altered to avoid favoring any one input port. In a fourth aspect, test pattern data are placed on the shared bus to monitor bus integrity. In a fifth aspect, the cell demultiplexer is divided into master and slave demultiplexer modules, which are coupled to different, parts of the shared bus.
摘要:
To provide a monolithic ATM transport the synchronous to asynchronous converter (SAC) of the invention converts the synchronous narrowband signals to composite cell ATM format. These cells can be combined with ATM video and data signals and can be delivered as an ensemble of ATM cells over either a standard SONET transport format or analog network to the customer premise. To convert the synchronous signals, the SAC provides format conversion needed to provide voice and other narrowband signals over ATM. The SAC also functions to agilely move between cell sizes such that the 48 bytes of the cell payload can be mapped to carry anywhere between the single and 48 connections. Thus, the SAC adjusts the cell configuration to balance performance and bandwidth use in a real-time manner.
摘要:
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.
摘要:
An ATM network switch and method of utilization for adaptively providing integrated services therein is disclosed. In providing such integrated services, if the allocated bandwidth for one connection has been consumed, or if the connection is not entitled to allocated bandwidth, the connection can optionally use dynamic bandwidth arbitration, or a combination of both allocated and dynamic. The switch includes an input port processor, a bandwidth arbiter, and an output port processor. Cells are transmitted from the input to the output, under the control of respective port processors and the bandwidth arbiter. Flow control is implemented on a per-connection basis. Individual queues are then assigned to traffic type groups in order to provide traffic type flow control. Based upon prioritization information associated with the cell at the input, cells are prioritized and transmitted from the output, with each cell maintained in the same order, relative to other cells on a connection, in which it was received.