Nortel Networks Corporation

Ciena Corporation

Northern Telecom Limited

Jeffrey T Gullicksen

Greg M Bernstein

William S Kish

Theodore Ernest Tedijanto

Neeraj Gulati

Richard W Conklin

Daniel E Klausmeier

Premal Desai

Gurpreet S Chhabra

Alan S Chapman

Neena Aluri

Philip K Edholm

Gregory M Bernstein

Anurag Kumar

Daniel E Klausmeler

Santosh P Abraham

Kenneth Gullicksen

A method, system and egress switching node for maintaining a network connection in an optical network reduces the number of spans needed for reestablishing a network connection. The invention learns which channels are used by the network connection and propagates such channel assignment data to the switching nodes for storage therein. When a span failure occurs, a notification is sent to the switching nodes identifying which span has failed. The switch nodes use the notification and channel assignment data to perform protection switching such that the rerouted network connection selects the channel that was used by the network connection on the failed span. Likewise, the egress switching node uses the selected channel to drop the network connection from the protecting fibers. This enables a network connection to travel a shorter distance after a protection switch.

Switching algorithm for optical fiber networks

A method of modeling or constructing a switch element uses an ingress stage with input sorters and input routers; an egress stage with output routers and output sorters; and a center stage interconnecting the ingress and egress stages. Routers are partitioned such that each partition is assigned to only one data line. A switch controller and method may use such modeling to advantage. For example, during initial configuration of the switch element, a subset of connections are excluded from a control algorithm that initially configures the switch with the subset being subjected to post processing. Furthermore, a fast rearrangement of the switch rearranges only part of the existing connections and then adds/deletes cross connects as necessary to complete the connections.

Switching control mechanism for supporting reconfiguaration without invoking a rearrangement algorithm

Systems and methods consistent with this invention allow for each node within one or more rings to obtain connection and topology information from other nodes within these rings. In such a system, each node is able to maintain connection table and topology tables for each node and each ring within a ring network. In particular, such information can be kept current because this scheme allows for dynamic updating of connection and topology information in real time. With such current information, a node is able to utilize this information to execute such operations as squelching connections on a protect line and timeslot interchange. In addition, by supporting timeslot interchange, the ring can be managed as more than a single logical entity as well as can have better bandwidth management utilization.

Virtual line switched ring (VLSR) connection state distribution scheme

A switch element is configured to extend communications between data lines. The switch element includes a set of ingress devices, a set of center stage devices, and a set of egress devices. Each center stage device is connectable to each ingress device and to each egress device. Each ingress device connects to a corresponding egress device across one of the center stage devices. The center stage switch can be selectively actuated to accommodate a new ingress or egress device across the center stage switch.

Switching control mechanism based upon the logical partitioning of a switch element

A switch is provided that includes three stages. The first stages has a plurality of switch circuits. The second stage has a plurality of switch circuits equal to N, where N is any integer other than a power of 2 and where the switch circuits can be logically configured into a logical configuration of a power of 2. The third stages includes a plurality of switch circuits.

Rearrangeable switch having a non-power of two number of physical center stages

A call made with a communication device is processed using multiple call processors (CPs) operatively connected to a network. CPs use processing load information from other CPs to select which CP will handle call set up when the call is requested. A similar selection process is used for selecting one of CPs to perform other call processing functions and to terminate the call upon receiving a request to terminate the call. The CP selected to set up a call, tear-down a call or perform other call processing depends on the load associated with the processor and the load associated with setting up, tearing down performing other call processing for the call.

Method and apparatus for processing calls on a multiprocessor communication system

A method and apparatus for efficiently transporting DS-X traffic in packet form over an ATM or other packet network. Specifically, virtual connection or slot provisioning and/or cell concentration techniques are used to compact the amount of DS-X traffic broadcast between communications system devices such as the access mux and the communications switch and spare bandwidth. In provisioning, a configured DS-X loading of an end node supporting DS-X traffic is ascertained. In turn, a minimum number of virtual connections for bearing packetized DS-X traffic are established, either at communications system configuration or as needed. In concentration processing, a dynamic association between the virtual connections and the DS-X traffic is established, typically on a per frame basis. Only those digital channels entering the node within a given time frame which actually bear DS-X traffic will be assigned a slot within packet. Concentration may be augmented by provisioning to further reduce bandwidth requirements. In other disclosed aspects, permanent virtual channels or PNNI soft permanent virtual connections may be used for the virtual connections where ATM is chosen as the transport protocol.

Method and apparatus for transporting DS-X signals through a packet network

Fairness is provided among network sessions contending for available bit rate (ABR) service in an asynchronous transfer mode network by determining congestion information on a per port basis. ABR cells are monitored to determine which rate information per outgoing port based on ABR cells leaving a switch. Using the ABR per port rate, the available capacity, and the input rate to output queues, a link congestion parameter (LCP) is determined. Resource Management (RM) cells traveling through the switch are monitored to determine whether the new LCP is lower than the explicit rate (ER) field in RM cell. If the new LCP is lower, the new LCP is stuffed into the RM cell. When the sender receives the LCP value, the sender output rate is adjusted based on the LCP. Because LCP is determined based on per port traffic flow, fairness is provided among session competing for available ABR capacity.

Apparatus and method for optimizing max-min fair rate control in ABR sessions

The benefits of Transport Control Protocol (TCP) over Available Bit Rate (ABR) Service of an Asynchronous Transfer Mode (ATM) network is extended to the entire TCP connection by intercepting and modifying TCP congestion control information in accordance with resource information associated with the TCP connection. An algorithm calculates a new advertised window size based on various network resource parameters, such as ABR. The advertised window is adjusted if the newly calculated window size is smaller than the advertised window size. By adjusting the TCP window, the normal extreme fluctuations of the TCP window are avoided.

Apparatus and method for optimizing congestion control information in a multi-protocol network

Methods and apparatus for accelerating a router in a communications network are described. In one embodiment, a router accelerator includes a forwarding table for associatively storing a destination address and a next hop address. If a destination address of a packet matches a destination address in the forwarding table, then logic forwards the packet to a next hop. A router may be coupled to at least one network port through the router accelerator. In another approach, the network includes at least one host and at least one router. The host has at least one routing table for associatively storing a second-level destination address, a second-level next hop address and a first-level next hop address. A router accelerator includes redirect logic for storing the second-level destination address in a second-level next hop address entry in the at least one host routing table. This causes the host to request a first-level next hop address corresponding to the second-level destination address. An accelerator table responds to the host's request with the bound first-level next hop address. In another approach employing host routing tables, a router accelerator includes request logic for requesting from the router a second-level next hop address in response to the first-level next hop address. Redirect logic stores the second-level next hop address in a second-level next hop address entry in the at least one host routing table. This causes the host to request a first-level next hop address corresponding to the second-level next hop address.

Method and apparatus for accelerating OSI layer 3 routers

A plurality of voice-over-ATM modules operate in parallel and each processes at least one type of AAL. Interface circuitry and contention circuitry allow the parallel modules to interact. The result is an interworking between ATM streams and different types of equipment.

Growing community of inventors

Santa Clara, CA, United States of America

Jeffrey T Gullicksen