Resource allocation for broadband networks

The major benefit of a broadband integrated ATM (asynchronous transfer mode) network is flexible and efficient allocation of communications bandwidth for communications services. However, methods are needed for evaluating congestion for integrated traffic. The author suggests evaluating congestion at different levels, namely the packet level, the burst level, and the call level. Congestion is measured by the probabilities of packet blocking, burst blocking, and call blocking. He outlines the methodologies for comparing these blocking probabilities. The author uses the congestion measures for a multilayer bandwidth-allocation algorithm, emulating some function of virtual circuit setup, fast circuit switching, and fast packet switching at these levels. The analysis also sheds insight on traffic engineering issues such as appropriate link load, traffic integration, trunk group and switch sizing, and bandwidth reservation criteria for two bursty services     

ATM-based transport architecture for multiservices wirelesspersonal communication networks

This paper presents an ATM-based transport architecture for next-generation multiservices personal communication networks (PCN). Such “multimedia capable” integrated services wireless networks are motivated by an anticipated demand for wireless extensions to future broadband networks. An ATM compatible wireless network concept capable of supporting a mix of broadband ISDN services including constant bit-rate (CBR), variable bit-rate (VBR), and packet data transport is explored from an architectural viewpoint. The proposed system uses a hierarchical ATM switching network for interconnection of PCN microcells, each of which is serviced by high-speed, shared-access radio links based on ATM-compatible cell, relay principles. Design issues related to the physical (modulation), media access control (MAC), and data-link layers of the ATM-based radio link are discussed, and preliminary technical approaches are identified in each case. An example multiservice dynamic reservation (MDR) TDMA media access protocol is then considered in further detail, and simulation results are presented for an example voice/data scenario with a proportion of time-critical (i.e., multimedia) packet data. Time-of-expiry (TOE) based queue service disciplines are also investigated as a mechanism for improving the quality-of-service (QoS) in this scenario     

Multirate scheduling of VBR video traffic in ATM networks

One of the major attractions of asynchronous transfer mode (ATM) networks for transporting bursty video traffic is its ability to exploit the multiplexing gains of packet switching while providing quality of service guarantees. Unfortunately, most of the multiplexing mechanisms proposed in the literature fail to exploit the multiplexing gains of ATM. We propose a multirate service mechanism that allows a session to be served at different rates at different times. Applications generating bursty data, such as variable bit-rate (VBR) video, can take advantage of multirate service by requesting a high rate of service for brief periods of bursty arrivals and a much lower rate of service for all other times. Consequently, the applications can improve their delay performance without reserving a high bandwidth for the entire duration of the sessions. Furthermore, the scheduler can multiplex the peaks and the lulls in service rates of different sessions and improve the utilization of the system. Using MPEG video traces from a number of applications, we show that multirate servers outperform single-rate PGPS (packet-by-packet generalized processor sharing) servers and CBR (constant bit-rate) servers in terms of number of connections admitted, while providing the same level of service guarantees. We also investigate the performance of multirate service when service quality need not be guaranteed. We refer to this as predictive service. We propose a measurement-based admission control procedure for predictive service, and show that it helps increase the size of the admissible region even further     

AAL2分组话音复接器的研究与实现

该文研究在ATM虚通路带宽利用率一定的条件下,AAL2分组话音复接器性能随ATM虚通路输出速率的增加而变化的情况。得出结论:当ATM虚通路带宽利用率一定时,ATM虚通路输出速率越高,AAL2分组话音复接器的分组丢弃概率和平均分组排队时延越小。并提出了一种AAL2分组话音复接器的实现方案。该方案可以随着ATM虚通路输出速率的增加,方便地复接多个E1话音电路上的话音数据。     

Providing Multiple-Channel Communication Using the Experimental Digital Switch

This report describes the functional characteristics of a circuit-switched network which is capable of providing data communication paths as well as voice channels. In the system described, the circuit switch may be shared in order to provide multiple independently switched paths through the network. Unlike a conventional circuit switch, this sharing permits only a fraction of the switching capacity to be consumed which is proportional to the allocated bandwidth of the path. Additional economy is gained by providing multiple communication paths over the single communication resource between the subscriber and the switching machine. The fraction of the communication resource which is used by the subscriber is proportional to the total bandwidth of the channels which have been allocated. This allocation is performed dynamically, in response to subscriber requests. Algorithms are presented which perform this allocation efficiently. The resulting network provides a communication vehicle which provides both data and voice services in an integrated fashion.     

Architecture design for ATM statistical multiplexers

Both high-speed packet switches and statistical multiplexers are critical elements in the ATM (asynchronous transfer mode) network. Many switch architectures have been proposed and some of them have been built, but relatively fewer statistical multiplexer architectures have been investigated to date. It has been considered that multiplexers are a special kind of switches which can be implemented with similar approaches. The main function of a statistical multiplexer, however, is to concentrate traffic from a number of input ports to a comparatively smaller number of output ports; ‘switching’ in the sense that a cell must be delivered to a specific output port is often not required. This implies that the channel grouping design principle, in which more than one path is available for each virtual circuit connection, can be applied in the multiplexer. We show that this technique reduces the required buffer memory and increases the system performance significantly. The performances of three general approaches for implementing an ATM statistical multiplexer are studied through simulations with various bursty traffic assumptions. Based on the best performing approach (sharing output channels and buffers), we propose two architecture designs to implement a scalable statistical multiplexer that is modularly decomposed into many smaller multiplexers by using a novel grouping network.     

MPEG—2在ATM网络的传输

随着ATM技术和编码技术的成熟,ATM上可以传送增强型媒体,这使得视听业务的广泛应用成为可能,主要讨论在ATM网络上恒定比特率（CBR）或可变比特率（VBR）的MPEG-2的传输,这涉及到适配层的选择,MPEG-2帧的封装,ATM业务类型的选择等问题。     

Unified approaches to integrated-service networks–burst and fast packet switching

The increasing demand for communication services, coupled with recent technological advances in communication media and switching techniques, has resulted in a proliferation of new and expanded services. Currently, networks are needed which can transmit voice, data and video services in an application-independent fashion. Unified approaches employ a single switching technique across the entire network bandwidth, thus allowing services to be switched in an application-independent manner. This paper presents a taxonomy of integrated-service networks, including a look at NISDN, while focusing on unified approaches to integrated-service networks. The two most promising unified approaches are burst and fast packet switching. Burst switching is a circuit switching-based approach which allocates channel bandwidth to a connection only during the transmission of ‘bursts’ of information. Fast packet switching is a packet switching-based approach which can be characterized by very high transmission rates on network links and simple, hard-wired protocols which match the rapid channel speed of the network. Both approaches are being proposed as possible implementations for integrated-service networks. We survey these two approaches, and also examine the key performance issues found in fast packet switching. We then present the results of a simulation study of a fast packet switching network.     

The evolution of packet switching

Over the past decade data communications has been revolutionized by a radically new technology called packet switching. In 1968 virtually all interactive data communication networks were circuit switched, the same as the telephone network. Circuit switching networks preallocate transmission bandwidth for an entire call or session. However, since interactive data traffic occurs in short bursts 90 percent or more of this bandwidth is wasted. Thus, as digital electronics became inexpensive enough, it became dramatically more cost-effective to completely redesign communications networks, introducing the concept of packet switching where the transmission bandwidth is dynamically allocated, permitting many users to share the same transmission line previously required for one user. Packet switching has been so successful, not only in improving the economics of data communications but in enhancing reliability and functional flexibility as well, that in 1978 virtually all new data networks being built throughout the world are based on packet switching. An open question at this time is how long will it take for voice communications to be revolutionized as well by packet switching technology. In order to better understand both the past and future evolution of this fast moving technology, this paper examines in detail the history and trends of packet switching.     

The fast packet ring switch: a high-performance efficientarchitecture with multicast capability

An architecture is presented for the packet switching of integrated traffic. It is based on the asynchronous routing of packets of varying size through regularly recurring dedicated time slots provided by a simple slotted-ring system. The architecture implements the distributed buffering and processing of packets, is data driven, and is designed to exploit fully the limited bandwidth of the ring system. Thus, switch modules of reasonable size and throughput are made feasible. The switch modules can be easily interconnected to achieve sufficient throughput for networking of services such as voice, data, image, and videoconferencing. The architecture provides a simple modular switching structure which does not suffer from the topological complexities and bottlenecks of those that use the staged Banyan-type networks for the switching of packets. Quasicircuit-switching can easily be achieved through selected ports with a peak bit-rate bandwidth allocation strategy in the switch control. Multicasting in particular is made simple and efficient in the current architecture. Moreover, it provides for the selective queueing of packets in the transmit ports     

Commercial, legal, and international aspects of packet communications

Packet switching technology emerged rapidly in the 1970's as another viable mode of communications switching, along with circuit and message switching. Since packet switching offers economical and versatile data communication capabilities in a multiuser environment, it is particularly well suited for furnishing public data communication network services. Public packet networks are now established or being developed in most industrialized countries, and the introduction of these networks has raised policy issues relating to the structure and regulation of the national networks, and the interconnection of national networks into an international packet switching system. This paper reviews these issues and concludes that public packet switching network services will continue to be regulated in all cases; that competitive packet networks will coexist in the U.S. and in Canada, but that only one national packet network will exist in each of most other countries; that packet networks will aggravate the problem of distinguishing nonregulated data processing services from regulated data communication services; that international interconnection of public packet networks based upon CCITT standanh will occur rapidly over the next several years; and that a unified international packet switching system will eventually emerge similar to today's international telephone and telex systems.     

多业务宽带交换

网络交换经历着一系列发展演变;从电路交换到分组交换;从软件交换到硬件交换;从单一网络业务交换到多种业务交换。多业务宽带交换需要协议机制的支持,如业务类型划分,网络资源预约和用户业务最监控等。目前主要的宽带交换网技术有千兆比以太网,千兆比路由器网和ＡＴＭ网三种。文章最后论述了多业务宽带分组交换网的原理和结构。     

Request rate control for QA services in DQDB/SMDS–ATM gateways

By the advancement of B-ISDN, ATM has been accepted as the future technology to integrate a variety of services as it is a fine comprise between circuit switching technology and packet switching technology. A cost-effective and simple way to realize the global network is to implement a backbone such as DQDB to interconnect the existing LANs and MANs to ATM. The major advantages of DQDB are the complete compatibility of different layers, the capability of handling real-time and non-real-time traffic and little degradation in delay performance with increase in network span and density. However, a major issue of concern in the design of a DQDB/SMDS–ATM gateway is the transparent transfer of non-real-time traffic, as ATM is basically connection-oriented in nature. In the absence of flow control schemes in high-speed networking, some sort of congestion control mechanism becomes an absolute necessity to reduce the cell loss ratio to the minimum and thus wastage in the network resources. In this paper we discuss the transfer of connectionless traffic in a DQDB–ATM interconnection. One of the two congestion control mechanisms for DQDB networks that we have proposed is discussed in detail. In the request rate control mechanism the bandwidth utilization in DQDB is restricted by controlling the request rate from the gateway. DQDB networks interconnected by gateways are modelled and simulated. The request rate congestion control mechanism is evaluated. Simplicity in implementation and effectiveness in performance are the highlights. © 1998 John Wiley & Sons, Ltd.     

ATM shared-memory switching architectures

ATM will provide flexibility in bandwidth allocation and will allow a network to carry heterogeneous services ranging from narrowband to wideband services. The challenge is to build fast packet switches able to match the high speeds of the input links and the high performance requirements imposed. The CCITT has standardized the asynchronous transfer mode (ATM) as the multiplexing and switching principle for the broadband integrated services digital network (B-ISDN). ATM is a packet and connection-oriented transfer mode based on statistical time division multiplexing techniques. The information flow is organized in fixed-size packets called cells, consisting of a user information field (48 octets) and a header (5 octets). The primary use of the header tag is to identify cells belonging to the same virtual channel and to make routing possible. Cell sequence on a virtual channel is preserved, a very low cell loss probability must be guaranteed (< 10^-12), and intensive error and flow control protocols are provided at the edges of the network     

An ATM switch architecture for provision of integrated broadbandservices

The author gives some qualitative performance targets to be fulfilled for the service classes proposed by CCITT for the future broadband-ISDN (B-ISDN) and proposes a nonblocking, self-routing asynchronous transfer mode (ATM) switching architecture that is able to fulfil the different performance figures of each class. To exploit the service integration accomplished by ATM switches, the switching bandwidth is allocated at call level and cell level. This allocation gives the flexibility of letting lower-priority services use the reserved bandwidth left temporarily unused by higher-priority services. The architecture adopts mixed input-output queuing. Input queuing is particularly suited to the definition of internal frame structures, making it possible to guarantee the absence of cell loss due to congestion for specific services (such as circuit emulation). Output queuing makes it possible to implement in hardware a switching speedup that practically removes the performance degradation due to the head-of-line blocking phenomenon typical of input queuing     

Video aggregation: adapting video traffic for transport overbroadband networks by integrating data compression and statisticalmultiplexing

Future broadband integrated services networks based on the asynchronous transfer mode (ATM) technology are expected to carry information from a large variety of different services and applications. This paper investigates video aggregation, a concept that integrates compression and statistical multiplexing of video information for transport over a communication network. We focus on the transmission of a group of video sessions as a bundle, the practical examples of which include entertainment-video broadcast and video-on-demand (VoD). In this situation, the advantage of constant bit-rate (CBR) transport (which facilitates simple network management and operation) and the advantage of variable bit-rate (VBR) video compression (which yields smoother image quality) can be achieved simultaneously. We show that it is better to integrate compression and statistical multiplexing before the bundle of video traffic enters the network than performing them as independent processes. We present experimental results which indicate the advantages of video aggregation in terms of superior image quality and efficient bandwidth usage     

Integrated Services on High Altitude Platform: Receiver Driven Smart Selection of HAP-Geo Satellite Wireless Access Segment and Performance Evaluation

A renewed interest in the development of high-altitude platforms (HAPs), which are stratospheric aircraft or airship carrying payloads tailored for a wide range of applications in telecommunications and remote sensing, is becoming progressively widespread. HAPs offer a reduced propagation delay and they are especially suitable for interactive multimedia services. In this paper, the inter-working between HAP and satellite segments in an integrated QoS architecture has been addressed. A new way to manage integrated services over a new hybrid wireless platform has been proposed. A smart terminal device has been considered in order to perform an intelligent switching on the wireless access segment. The switching criteria applied in the HAP/satellite architecture is based on the available bandwidth and on the admissible data packet end-to-end delay. Performance evaluations of the integrated HAP–satellite platform have been evaluated in terms of bandwidth utilization and number of admitted calls. The simulations show an improvement of admitted calls, reduced data packet end-to-end delay and increased bandwidth utilization.     

未来光因特网中的光交换方式及其发展趋势

Internet的业务流量正以每六个月翻一番的速度快速增长,未来网络中,数据业务超过话音业务只是时间问题,因此,基于电路交换的电信网升级到支持基于分组交换的数据业务是不可避免的,但是对因特网来说,由于光逻辑与光存储等器件不成熟,发展全光分组交换,技术上异常困难。另一方面,近来新提出的光突发交换,技术上相对简单,性能特点优异,因而成为更理想的选择,本文介绍了全光分组交换和光突发交换的研究现状,比较了两者的优缺点,最后指出改进光突发交换性能的两种方式。     

Breakthrough technologies for the high-performance electrical ATMswitching system

A high-performance electrical asynchronous transfer mode (ATM) switching system is described with the goal of Tb/s ATM switching. The first step system was to use advanced Si-bipolar very large scale integrated (VLSI) technologies and the multichip technique. 1.0 μm bipolar SST technologies and Cu-polyimide multilayer MCM realized a 160 Gb/s throughput ATM system. The performance limitations of the 160 Gb/s system were power supply/cooling and module interconnection. The new ATM switching system, named OPTIMA-1, adopted optical interconnection/distribution to overcome the limitations and achieve 640 Gb/s. The system uses high-performance complementary metal-oxide-semiconductor (CMOS) devices and optical wavelength division multiplexing (WDM) interconnection. Combining OPTIMA-1 with optical cell-by-cell routing functions, i.e., photonic packet routing, can realize variable bandwidth links for 5 Tb/s ATM systems. This paper first reviews high-performance electrical ATM (packet) switching system architecture and hardware technologies. In addition, system limitations are described. Next, the important breakthrough technology of optical WDM interconnection is highlighted. These technologies are adopted to form OPTIMA-1, a prototype of which is demonstrated. The key technologies of the system are advanced 80 Gb/s CMOS/MCM, electrical technologies, and 10 Gb/s, 8 WDM, 8×8 optical interconnection. Details of implementation technologies are also described. Optical cell-by-cell (packet-by-packet) routing is now being studied. From the architectural viewpoint, dynamic link bandwidth sharing will be adopted. In addition, an AWG that performs cell-by-cell routing and a distributed large scale ATM system are realized. Optical routing achieves the 5 Tb/s needed in future B-ISDN ATM backbone systems     

Internetworking based on cell switch router-architecture andprotocol overview

This paper describes an internetworking architecture and related protocol overview based on routers that have asynchronous transfer mode (ATM) cell switching capability in addition to conventional Internet protocol (IP) packet forwarding. The proposed architecture can provide high-throughput and low-latency switched paths for individual application flows or a group of application flows while retaining current router-based internetworking architecture. The proposed router is able to establish the switched path based on the characteristics of flows, e.g., arrival of a data packet with specific upper layer protocols or arrival of more than a certain amount of data packets in a predetermined period, as well as by the reception of an IP-layer resource reservation request, such as resource reservation protocol (RSVP). One important feature that is provided by the proposed router is interoperability with the emerging ATM network platform specified by the ATM Forum and the telecommunications sector of the International Telecommunications Union (ITU-T). The proposed routers can be interconnected with each other over the point-to-point synchronous optical network link as well as over the ATM network platform, which provides permanent virtual channel, virtual path, or switched virtual channel (SVC) services. That enables network carriers to provide Internet/intranet services as well as others, such as telephony, ATM/time division multiplexing leased line, or native ATM SVC services