In a method of controlling overloads in a telecommunications network, a module (46) for detecting and monitoring overloads is provided at a node (40). The node (40) includes a module (44) for controlling access to terminal resources such as telephones and fax machines. The module (44) also detects failed calls. Upon detecting an initial failed call to a particular called party number, a counter in module (46) is initialised. The counter is incremented for each further failed call to the particular called party number and also decremented at a fixed rate. When the number of calls in the counter rises above a first threshold, the counter goes into an overload state. When the number of calls in the counter falls below a second threshold, the counter goes into a no overload state. The module (46) sends an indication of the state of the counter and the identity of the called number to a module (48) in a node (41) which sets and updates a restriction parameter. The node (41) is upstream from the node (40) in the direction of call set up and the overload status is transmitted in the backward call set up messages. The module (48) then sets the restriction parameter in accordance with the overload status of calls to the called number and supplies this parameter to a module (49) which restricts calls to the called number. Call restriction is maintained until the overload to the called number subsides completely. The invention may also be used to detect and control calls whose call identities belong to a common set of call identities.

A method of controlling overloads in a telecommunications network

This book describes, analyzes, and recommends traffic engineering (TE) and quality of service (QoS) optimization methods for integrated voice/data dynamic routing networks. These functions control a network's response to traffic demands and other stimuli, such as link failures or node failures. TE and QoS optimization is concerned with measurement, modeling, characterization, and control of network traffic, and the application of techniques to achieve specific performance objectives. The scope of the analysis and recommendations include dimensioning, call/flow and connection routing, QoS resource management, routing table management, dynamic transport routing, and operational requirements. Case studies are included which provide the reader with a concrete way into the technical details and highlight why and how to use the techniques described in the book.

* Includes Case Studies of MPLS & GMPLS Network Optimization
* Presents state-of-the-art traffic engineering and quality of service optimization methods and illustrates the tradeoffs between the various methods discussed
* Contains practical Case Studies based on large-scale service provider implementations and architecture plans 
* Written by a highly respected and well known active expert in traffic engineering and quality of service

Traffic Engineering and QoS Optimization of Integrated Voice & Data Networks

The paper presents a centralized virtual path bandwidth (VPB) control scheme for ATM networks which satisfies mainly three specifications: a) optimality during a medium-term control interval, b) fast time response so as to absorb the medium-term traffic fluctuations, and c) easy implementation. The paper mainly points at the impact of direct, on-line traffic measurements on bandwidth control. The control objective is to rearrange the installed bandwidth of the virtual paths according to the offered traffic so as to minimize the maximum call blocking probability of the whole network. Network simulation shows that a sophisticated VPB controller which relies on simple measurements of the offered traffic can substantially improve the performance of an ATM network. The necessary bandwidth rearrangement time is also examined by simulation. >

Medium-term centralized virtual-path bandwidth control based on traffic measurements

Major issues that should be examined in evaluating the performance of networks with dynamic routing are reviewed The characteristics of international 24-h traffic profiles are examined, and proposed dynamic routing schemes are described Gain allocation principles are discussed, and results on circuit savings and fault tolerance of international dynamic routing networks are outlined >

Dynamic routing schemes for international networks

In this paper, three related virtual channel routing problems on Broadband ISDN are investigated and shown to be NP-complete A distributed routing heuristic is proposed to reduce the call blocking rate while preserving a fast call setup time Various traffic patterns and network topologies are employed to evaluate the performance of the proposed heuristic by simulations Two existing famous routing schemes are also applied for comparison The simulation results show that the proposed heuristic performs better in most cases than the other two schemes

Some routing problems on broadband ISDN

The objectives of network management control are outlined, and two categories of control are defined: network traffic controls and network configuration controls. Network traffic controls are further classified into traffic volume controls and routing controls, and advanced techniques for achieving each of them are examined. Two classes of methods for specifying the amount of traffic to be controlled are described. In proportional control, a certain proportion of the traffic offered by each exchange is admitted; in threshold control, there is a maximum rate at which the traffic offered by each exchange is admitted. The TCS-V2 traffic-control system, an advanced automatic code-blocking system that uses area and subscriber congestion control, is considered, and the simulated performance of proportional control and threshold control is compared for this system. For routing control, an advanced state-dependent dynamic routing scheme is examined, and the results of a comparative evaluation of dynamic routing schemes are presented. >

H. Yamamoto

Papers

Advanced traffic control methods for network management