A feedback control system for congestion prevention in a cell (packet) switching communication network is described. Congestion control is accomplished by controlling the transmission rate of bursty traffic in the presence of high priority, voice, low speed statistical, high speed deterministic and multicast data. Because bursty traffic is relatively insensitive to delay, adequate buffercapacity can be provided at the network nodes in order to minimize bursty data cell loss. By monitoring the buffer queue lengths at the nodes, a control signal can be generated at each intermediate node indicating the state of congestion. Excess queue length indicates incipient congestion while short queue lengths indicate excess capacity. Queue status is forwarded to the destination node where it is interpreted and sent back to the source node as a feedback rate control signal using a 2-bit code. The source node regulates the rate of bursty data transmission over the cell network in accordance with the feedback control signal thus minimizing congestion and concomitant data loss while efficiently utilizing available network bandwidth.

Congestion control for cell networks

According to the present invention, a method and system provides the ability to assign requests for data objects made by clients among multiple network servers. The invention provides a distributed computing system and methods to assign user requests to replicated servers contained by the distributed computing system in a manner that attempts to meet the goals of a particular routing policy. Policies may include minimizing the amount of time for the request to be completed.

Method and apparatus for balancing the process load on network servers according to network and server based policies

A telecommunications switching system employing multi-protocol routing optimization which utilizes predetermined and measured parameters in accordance with a set of user priorities in determining the selection of a telecommunications path to be utilized for transmitting a data file to a remote destination. The switching system has a first memory for storing the data file to be transferred, a second memory for storing predetermined parameters such as cost data associated with each of the telecommunications paths, a third memory for storing a set of user priorities regarding the transmission of data files, and means for measuring the value of variable parameters such as file transfer speed associated with each of the telecommunications paths. Processor means are operatively associated with the second and third memories and the variable parameter measuring means for determining which of the plurality of telecommunications paths should be utilized for transferring the data file in accordance with the set of user priorities, the predetermined telecommunications path parameters, and the measured variable parameters. The switching system further comprises input means for allowing a user to change the user priorities in the third memory prior to transmitting a file.

Multi-protocol telecommunications routing optimization

A system for selecting options for modifying a network architecture in accordance with user preferences using a knowledge base and a database. The knowledge base includes rules to select modification categories and the database includes information on a plurality of equipment and a plurality of tariffs. To select the options, the system generates a base-line simulation from the network architecture, which base-line simulation includes performance data on the network architecture under a predetermined scenario. Modification categories based on the user preferences are selected using rules in the knowledge base, and equipment information and tariff information corresponding to the network modification categories are selected from the database to create modification options for the network modification categories. The modification options are evaluated using rules in the knowledge base. The system then generates a plurality of new simulations of the network architecture as modified by the modification options, and compares the performance data of the base-line simulation with performance data of the new simulations to specify differences in performance data between the base-line simulation and each new simulation. Finally, the modification options (each corresponding to one of the new simulations) are ranked using the specified differences in performance data between the base-line simulation and each new simulation, user preferences, and rules of the knowledge base.

Automated network simulation and optimization system

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, ie, 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 A modified Bellman-Ford breadth-first search algorithm is used to identify the principal links and, using these principal link identifications, determining the optimum path

Method and apparatus for optimum path selection in packet transmission networks

In a communication network, in which a plurality of switching nodes are connected with each other through a plurality of relay lines and one of the switching nodes acts as a center node for network routing, the center node estimates the state of delay of data for every relay line on the basis of information previously inputted, indicating the communication network configuration, and the state of delay of data reported by each of the switching nodes, and informs each of the switching nodes of said estimated state of delay of data. Each of the switching nodes determines and selects the relay line giving the shortest delay of data for every destination, to which it outputs data, on the basis of the state of delay at the relevant switching node itself and that received from the center node.

Routing control method in a packet switching network

PURPOSE:To improve the stability for routing change by by-passing respective destination exchanges stepwise in accordance with states of queue length abnormality of lines with destination exchanges as units CONSTITUTION:Queue lengths of lines l1 and l2 are counted; and if they are different from each other, destination packet exchange which divides traffic into two or more directions with respect to the same destination are ob tained and only lines whose queue lengths are shorter are defined as transmission directions If exchanges are already by-passed to the line l1, having the longer queue length in case that lines l1 and l2 are different in queue length, one exchange is selected from them and by-pass of this exchange is immediately stopped Thus, if an abnormality of queue length occurs, the number of releating hops to all destination exchanged in the pertinent direction is increased by one and the transmission direction is changed in accordance with this number of repeating hops

Routing control system for packet switching network

PURPOSE:To reduce the processing value of table distribution by extracting the changed parts of a routing table compared with the previously distributed one and informing these changed parts only to the switching stations and switching modules requiring the routing tables when these tables are distributed CONSTITUTION:A packet switching network consists of a network control station 1, packet switching stations 2-5, and a trunk circuit which securs mutual connections among these stations the station 1 has a function to produce the routing tables based on the state reports of stations 2-5 and to distribute them to each switching station in addition to a normal exchange function When the routing tables are distributed to the stations 2-5 from the station 1, the changed parts of the table are extracted in comparison with the previously distributed one These changed parts are information only to the switching stations that require the routing tables, thus Thus it is possible to reduce the routing table value when these tables are distributed to the stations 2-5 from the station 1

Control system for routing information of packet switching network

PURPOSE:To rapidly recover a switching node to a network due to the generation and recovery of a fault even when management for a sequence number is performed by controlling the sequence number managed by the switching node so as to be synchronized with the sequence number of a received packet. CONSTITUTION:In case of performing re-transmission by a retry operation without receiving a response for flooding by terminals 31-33 which transmit flooding packets, an instruction to synchronize the sequence number managed by the switching nodes 1-6 is issued compulsorily. Also, each of the switching nodes 1-6, in case of receiving the packet of compulsory instruction for the sequence number, controls the sequence number being managed by its own station so as to be synchronized with that of the packet. Therefore, when the switching node is not isolated, it is synchronized with ordinary sequence control, and only when it is isolated due to the fault and recovered again, the sequence control functions compulsorily. In such a way, it is possible to prevent malfunction from being generated, and to perform a packet switching processing rapidly.

Packet switching network control system

PURPOSE:To evade discrepancy between a network state recognized by a centralized control station and an actual network state from being generated, by setting a normal state when a required condition is satisfied after receiving the recovery of a line from a faulty state to the normal state by the centralized control station. CONSTITUTION:For example, the fault of the line l1 is reported from a packet switching machine 5 to the centralized control station 4. In this case, a report from a packet switching machine 6 passes through a packet switching machine 9, and the generation of the fault of the line l3 on which the fault has been generated already is not received by the station 4. And after the recovery of the line l1 is reported, the station 4 sets a timer start normal state 3, and sets the normal state of the line l1 after the lapse of a timer time. Therefore, it is possible to evade the discrepancy between the network state recognized by the centralized control station and the actual network state due to the invert of an arrival order from being generated even when the line l3 is recovered to the normal state during that time.

Kano Takashi

Papers

Routing control method in a packet switching network

Routing control system for packet switching network

Control system for routing information of packet switching network

Packet switching network control system

System for managing network state of packet switching network