Management of capacity and control in broadband ISDN

The trend towards integration of services onto a single network and the addition of accompanying control features has led to an increase in the complexity of functional signalling protocols. A continuing dramatic reduction in the cost of traffic-carrying capacity has meant that call control costs are becoming an increasingly significant component of the total network cost. In BISDN, the support of many diverse services may result in an excessive control cost. To avoid this potential problem, virtual paths may be used. Capacity may be reserved on virtual paths to simplify the set-up procedure for individual calls. One benefit of this approach is that the cost of establishing a virtual path is shared among all individual connections which subsequently use it. However, this reduced control cost comes at the expense of installing additional traffic carrying capacity. This paper describes techniques for the management of traffic carrying capacity and control mechanisms in BISDN and presents a cost-benefit analysis to determine policies for reserving capacity on virtual paths. Significant savings in the total BISDN cost can result from the use of virtual paths.     

Expanse software for distributed call and connection control

The experimental ATM network services environment (EXPANSE) prototype provides an experimental testbed for multimedia multiparty telecommunications services over heterogeneous communications networks. The EXPANSE software architecture supports the functional separation of call and connection control. At the call control layer an object-oriented, transaction-based call model provides for the co-ordination of the negotiations among users for the establishment, modification and disconnection of telecommunications services. The connection control layer provides an object-oriented protocol for the dynamic establishment, modification and release of network connections which include the control and allocation of network resources required for multimedia multiparty services. The EXPANSE software includes an application programming interface (API) to the signalling protocol at the call control level. The API provides a uniform and powerful interface to the call model and allows different applications to co-ordinate the control of local resources and session state.     

Omissions and ambiguities in CCITT Recommendation Q.921

The data link layer protocol for the integrated services digital network (ISDN) user/network interface, known as link access protocol-D (LAPD), is a protocol that operates at layer 2 of the open systems interconnection (OSI) architecture. Its purpose is to safely convey information between layer 3 entities using the D-channel. The information types that LAPD is intended to transport include call control signaling, packet mode communications, and management information. Observations are made in this article about what are, in the authors' opinion, the most confusing points of CCITT Recommendation Q.921 with comments related to data link layer address field, broadcast connections, terminal endpoint identifier (TEI) management procedures, layer 2 frames exchange, and connection management entity response to MDL-error indication primitives. This article intends solely to clarify the recommendations so that their concepts and procedures become easier to understand and implement, which can lead to significant saving of time for those who must eventually use LAPD procedures or develop the software for handling them     

TOPS: an architecture for telephony over packet networks

Packet telephony is of increasing interest in both the telecommunications and Internet communities. The emergence of packet telephony will create new services, and presents an opportunity to rethink how conventional telephony services are implemented. In this paper, we present an architecture for telephony over packet networks (TOPS). TOPS allows users to move between terminals or to use mobile terminals while being reachable by the same name. TOPS users can have multiple terminals and control how calls are routed to them. TOPS allows for terminals with a range of capabilities such as support for video, whiteboard, and other media with a variety of coding formats. TOPS retains the necessary information on terminal capabilities to determine the appropriate type of communication to be established with the remote terminal. The architecture assumes that the underlying network supports the establishment of end-to-end connectivity between terminals, with an appropriate quality of service. The components of TOPS are a directory service, an application layer signaling protocol, and a logical channel abstraction for communication between end-systems. The directory service maps a user's name to a set of terminals where the user may be reached. A user can control the translation operation by specifying profiles that customize how his name is mapped to a set of terminals where he can be reached. Terminal capabilities are also stored in the directory service. The application layer signaling protocol establishes and maintains call state between communicating terminals. The logical channel abstraction provides a shared end-to-end context for a call's constituent media and control streams, while isolating the applications from the details of the network transport mechanisms. In addition to supporting simple point-to-point calls, the architecture supports both centralized and decentralized conferencing. We also introduce a simple encapsulation format for voice     

移动栅格网中跨层资源管理方法研究

移动栅格网是一种全移动多跳无线栅格网络,采用了面向服务的全IP技术体制和全新的分层协议模型。针对这种新型网络结构和协议模型,提出了一种跨层资源管理方法,通过将呼叫接纳控制、路由选择、资源预留、排队机制以及信道接入机制等进行跨层设计,增加层间协作机制和方法以达到资源利用的优化和业务服务质量的提高。对跨层资源管理的总体框架和思路进行了详细描述,对具体实现途径进行了探讨。     

An object-oriented analysis of a BISDN control system with a focus on the UNI protocol object

The control system of a BISDN network will undoubtedly be very complex to design, implement and maintain. Its complexity has led researchers to look for ways of breaking down the problem into smaller and manageable parts. This has motivated the use of an object-oriented approach to analyse and comprehend the BISDN control system. This paper thus presents an object-oriented analysis (OOA) of a BISDN control system. This analysis is based on a method introduced by Coad and Yourdon and comprises five steps. All five steps, namely identifying subjects, identifying objects, identifying structures, defining attributes, and defining operations, will be worked out in detail with an emphasis on the user network interface (UNI) signalling protocol object. Four subjects, nine objects, and three structures are identified in the problem space at hand. This structuring offers a framework to analyse in detail the three aspects, data, structure and dynamic behaviour, of the UNI signalling protocol. A parallel between this approach and the well known approach used by the International Telecommunication Union (ITU) for specifying signalling protocols and contained in Recommendation I.130 is drawn. The Coad and Yourdon OOA approach applied to a BISDN control system can be used for the analysis of different aspects of such systems. This paper focuses on the UNI signalling protocol object which leads to a complete specification. Any protocol resulting from such analysis can be claimed to be object-oriented protocol. This approach offers modularity and thus offers a way of structuring the problem space into identifiable objects and data. Full benefits of object orientation can be gained only in the consistent use of object orientation throughout all steps in the development process. The proposed approach allows one to create libraries of generic procedures which can be reused in specific implementations.     

A promising application for broadband ISDN: Hypermedia teleconference

The optimum BISDN teleconference service for business, called hypermedia teleconference, is designed based on research into typical business activities and ATM, the most promising BISDN architecture. Service characteristics are determined by analysing the daily work practices of a large set of businessmen. It is shown that communication tasks occupy 44 per cent of the working day. The analysis further shows that some 60 per cent of all communication tasks could be performed through an advanced digital teleconference service. Hypermedia teleconference is designed to satisfy the needs of business through personal communication terminals and ATM public networks. The terminals effectively allocate the BISDN's high-speed transmission capability between a number of subchannels that realize distributed multipoint connection links and multimedia paths. The terminals use a new variable-bit-rate ATM codec created to realize high quality video. Users can easily create full featured teleconferences without a centralized connection facility. Terminals allow the synergistic combination of video, voice, telewriting, telepointing and document transmission services.     

Optical broadband access using ATM on a passive optical network

Within the framework of the ‘FITL (fibre in the loop) evolution’, Siemens is developing a prototype based on a passive optical network (PON) for the economic provision of BISDN services in the subscriber access area. It provides 32 subscribers with BISDN access up to a maximum user data rate of 45 Mbit/s per subscriber. The information is transferred via ATM cells and PON-specific overhead in both directions on the PON at a data rate of 155.52 Mbit/s. For transmission to the subscribers, the time division multiplex procedure (TDM) is used. For transmission in the opposite direction, a highly flexible time division multiple access procedure (TDMA) controls the access to PON for the subscriber-side line terminations. In order to keep the transmission system inexpensive emphasis is placed on a digital calibration of the fibre loop delay, a burst transmitter at the subscriber side without amplitude recovery and a burst receiver at the exchange side with purely digital bit synchronization. However, to achieve these features a small part of data rate must be used as a PON specific overhead.     

Broadband Island interconnection via satellite—performance analysis for the race II—catalyst project

The use of communication satellites as a possible way of offering broadband island interconnectivity appears to be a very attractive option, as it will enable the provision of an all-digital, transparent service to a number of ATM islands spanning a wide area, accommodating efficiently a variety of traffic demands. The CATALYST Project (RACE II/R2074) is an attempt to demonstrate the applicability and compatibility of satellite technology with the terrestrial BISDN. In this paper we present an overview of the project and focus on an initial study of the expected user performance through the CATALYST network. Our analysis is based upon mathematical and simulation models and describes the end-system to end-system transfer delay for given message lengths. The protocol profiles assume a mix of Novell NetWare and Network File System client/server architectures, which are supported by either the IEEE 802.3/Ethernet or fibre distributed data interface LANs, which are themselves linked via LAN/ATM/satellite interface units. Areas of further investigation, and the implication of our analysis on the actual network architecture, are discussed.     

Broadband ISDN — service visions and technological realities

Two forces, service needs and technological advances, are driving the extension of the Integrated Services Digital Network (ISDN) into the broadband area. First, this paper identifies several business and residential services which provide a market pull for broadband ISDN (BISDN). Secondly, it reviews recent advances in optical transmission and broadband switching which provide a technological push. Finally, it describes an experimental broadband prototype constructed to help us better understand the transmission, switching, signaling protocol, software, and service capabilities required for BISDN.     

Object-oriented analysis of signalling and control in broadband networks

This paper analyses the problem of providing call, connection, channel, and service control in broadband and intelligent networks to support a wide variety of services. A formal methodology called object-oriented analysis (OOA) is used to analyse this problem. Three types of OOA models are constructed: the information model, state models and the object communication model. From these models, a distributed call processing architecture that proposes separate servers for call control, connection control, channel control and service control, is derived. Based on the events used for inter-object communication in the object communication model, service-specific and control-function specific application service elements are defined as client-server based protocols.     

Hybrid Control and Reservation Architecture for Multidomain Burst Switched Network

Optical burst switching realizes all-optical communication by dividing data transmission system into control plane and data plane. In order to implement control plane two controlling mechanisms such as distributed and centralized control and reservation models have been presented in literature. Both of the architectures have pros and cons associated such as distributed model lacks efficient resource utilization while centralized model is nonscalable. In order to overcome these, a new hybrid control and reservation mechanism has been presented by the authors. The proposed model is based on clustering technique where each cluster consists of cluster head and member nodes. Cluster head performs major functionalities in the network such as path establishment, routing and resource management, fault management, etc., while member nodes perform data switching functionality. In order to implement the architecture, a signaling protocol is also presented. In this paper, we discuss different scenarios required for the implementation of the proposed hybrid model. These scenarios detail the message dialogs exchange between different network nodes and between different software modules during lightpath establishment, data transmission, and connection teardown operations. The goal of efficient resource utilization is achieved through centralized control of network resources while scalability is achieved through dividing the network into multiple domains. Finally, the simulation section shows the mechanism of designing the multidomain architecture, network bandwidth utilization comparison and reduction in end-to-end data transmission latency.      

物联网云平台终端远程更新技术研究与应用

物联网终端远程更新是支持其迭代式优化、规模化部署和低成本维护的基础。分析了物联网终端远程更新现状与统一管理控制需求间的矛盾,基于LWM2M协议提出了物联网终端远程升级技术解决方案,探讨物联网云平台对异构式操作系统、多形态终端远程更新的统一管理和控制,降低了终端规模升级对网络冲击,提高远程更新的通用性、可靠性和稳定性。     

一种基于CORBA和TMN结构的ATM网络管理模型

本文给出了一种基于CORBA和TMN结构的ATM网络管理模型。首先介绍模型的OS结构,并将ATM与其传输网SDH进行集成管理;其次定义了该模型在不同域之间交换信息的接口,即所谓的Xcoop。结果表明该模型能够实现分布式网络管理、保证宽带连接业务的端到端QoS,并且有故障管理和配置管理功能。     

Standardization of a multi-configuration medium access protocol for broadband ISDN

This paper examines the current work within various standards bodies to define a multi-configuration medium access control (MAC) protocol for operation between broadband ISDN terminals. To begin, the configurations in which the MAC protocol is expected to operate are introduced. The relation between the MAC protocol and the broadband ISDN resource allocation schemes is then discussed. Several MAC protocol proposals currently being discussed in various standards bodies, each with unique assumptions regarding resource allocation in broadband ISDN, are then described and compared. Finally, areas for future work on this topic are identified.     

Narrowband and broadband ISDN CPE directions

Noting that ISDN customer premises equipment (CPE) is critical to the successful deployment of ISDN whatever the bandwidth, the author examines the market for narrowband and wideband integrated services digital network (NISDN and BISDN) CPE. He establishes the basic requirements for NISDN terminals and discusses terminal adaptors, digital telephone sets, screen-based telephony, workstations, customer premises networks, and CPE maintenance and upgrades. He examines the BISDN market and discusses the features and architecture of the terminals     

World-wide standardization of broadband ISDN

A growing market demand for high-performance voice, data, image and video networks, coupled with advances in high-speed technologies has heightened interest in broadband ISDN (BISDN) throughout the world. Network providers, equipment manufacturers and standards bodies are working jointly to accelerate the definition of BISDN interfaces in anticipation of emerging market opportunities. BISDN is being designed as the foundation upon which to implement very flexible, high-bandwidth, high-performance networks. A multiplexing concept called asynchronous transfer mode (ATM), which can offer bandwidth on demand at rates exceeding 150 Mb/s, high-speed packet switching, and an efficient protocol which adapts existing information streams into the ATM format are key attributes of the emerging BISDN network standards. This paper reviews the motivations behind BISDN, explains its key attributes and challenges and discusses possible strategies for evolving today's network toward BISDN.     

A hybrid architecture for analog video broadcast and B-ISDNservices in customer premises networks

The use of SCM (subcarrier multiplexing) transmission to deliver broadcast analog video signals within a CPN (customer premises network) as an overlay to an all-digital B-ISDN (broadband integrated services digital network) is considered. The feasibility of a proposal where the analog and digital signals are carried on different wavelengths is shown. An architecture for an optical CPN, termed H-Bus and incorporating emerging broadband SONET and ATM (asynchronous transfer mode) standards, is taken as a baseline for the delivery of switched digital, two-way voice, data, and video services. An optical overlay for the distribution of analog, broadcast video services using subcarrier multiplexing is considered. Several key alternatives associated with the delivery of broadcast video services are assessed, including signal quality, number of simultaneous channels, number of user terminals to be served, and modulation format. These issues are considered in terms of their impact on the interface with the public local exchange network and on the complexity, topology, and cost of the CPN     

Generic signaling protocol: architecture, model, and services

The functional architecture, connection model, and services of the generic signaling protocol (GSP) are described. GSP is a simple, yet powerful, connection management protocol for ISDN. The semantics and structure of GSP support call suspension and resumption, symmetric and asymmetric bridging, third-party `proxy' call setup, and multiple-connection multimedia calling. GSP can function as a network access, interswitch, computer-to-switch, or network configuration protocol, and it has applications in circuit-switching and packet-switching networks. An example message flow demonstrating how GSP can be used to perform third-party call setup is provided     

Generic signaling protocol: switching, networking, and interworking

The authors show how to design communication networks that are based upon the generic signaling protocol (GSP see ibid., vol.40, no.5, p.957-66, 1992), a simple but powerful connection management protocol. They define the output of a switching system that has multiple GSP interfaces, both its switching output and its event notification output. The behavior of an entity that provides transparent GSP networking is specified and the messages exchanged during an example interswitch call are listed. Also discussed is a scheme that allows a network to evolve its interswitch signaling gradually toward GSP, and to continue to support older network access protocols (e.g. DTMF and Q.931). The advantageous capabilities of GSP are enumerated by comparing GSP to the initial set of ISDN call setup protocols and X.25