Delay-tolerant networking: an approach to interplanetary Internet

Increasingly, network applications must communicate with counterparts across disparate networking environments characterized by significantly different sets of physical and operational constraints; wide variations in transmission latency are particularly troublesome. The proposed Interplanetary Internet, which must encompass both terrestrial and interplanetary links, is an extreme case. An architecture based on a "least common denominator" protocol that can operate successfully and (where required) reliably in multiple disparate environments would simplify the development and deployment of such applications. The Internet protocols are ill suited for this purpose. We identify three fundamental principles that would underlie a delay-tolerant networking (DTN) architecture and describe the main structural elements of that architecture, centered on a new end-to-end overlay network protocol called Bundling. We also examine Internet infrastructure adaptations that might yield comparable performance but conclude that the simplicity of the DTN architecture promises easier deployment and extension.     

AdaptNet: an adaptive protocol suite for the next-generation wireless Internet

Over the last decade, the tremendous growth in the mobile Internet user population has been accompanied by an equally exciting evolution in wireless data networks. However, quite understandably, the evolution has been distinctly characterized by an increasing degree of heterogeneity along several dimensions such as the access technology, network model, device, and application requirements. This heterogeneity, in turn, imposes a significant challenge on the design of the network protocol stack, and leads to the question: how can the protocol stack at a mobile host cater effectively to the heterogeneous characteristics of the operating environment? In this article we provide an overview of AdaptNet, an adaptive protocol suite for next-generation wireless data networks. AdaptNet consists of protocol solutions at different layers of the protocol stack addressing several problems, including rate adaptation, congestion control, mobility support, and coding. A common underlying theme in the design of the protocols in the AdaptNet suite is adaptiveness to the operating environment. Through high-level discussions, preliminary results, and pointers to relevant related work, we show how AdaptNet achieves the goal of effectively addressing heterogeneity in next-generation wireless data networks.     

Bridge-on-chip: the enabler of next-generation mobile Internet andvoice-over-IP

A bridge-on-chip (BoC) is a highly integrated yet flexible microprocessor-based Ethernet bridging device. It integrates Bluetooth (technology that enables links between mobile computers, mobile phones, portable handheld devices, and connectivity to the Internet) baseband functionality and an Ethernet controller and on-chip memory in a single chip. It also provides a DSP-based media gateway in support of voice-over-IP (VoIP), and it comes with a full range of embedded TCP/IP software support for various applications. The BoC is a key enabler for real integration of the data and telecommunication networks and services     

Optical data networking: what bubble?

Armed with the market wisdom of the past three years, this article revisits a vision of "optical data networking," originally penned in March 2000, and looks ahead toward a future tempered by the realities of the "optical bubble".     

Evolving toward the next-generation Internet: challenges in thepath forward

Most people would agree that the Internet is one of the great technical and business success stories of the 20th century, notwithstanding the financial losses that have been experienced by overly optimistic and speculative investors. Even in the context of the current dramatic slowdown in telecommunications investment, the Internet and its supported applications are continuing to revolutionize almost all aspects of our business and personal lives - mostly for the better. The author reviews a subset of the challenges that lie ahead in evolving the Internet to meet the growing and changing needs of its users     

A flexible and distributed architecture for adaptive end-to-end QoS provisioning in next-generation networks

A novel distributed end-to-end quality-of-service (QoS) provisioning architecture based on the concept of decoupling the end-to-end QoS provisioning from the service provisioning at routers in the differentiated service (DiffServ) network is proposed. The main objective of this architecture is to enhance the QoS granularity and flexibility offered in the DiffServ network model and improve both the network resource utilization and user benefits. The proposed architecture consists of a new endpoint admission control referred to as explicit endpoint admission control at the user side, the service vector which allows a data flow to choose different services at different routers along its data path, and a packet marking architecture and algorithm at the router side. The achievable performance of the proposed approach is studied, and the corresponding results demonstrate that the proposed mechanism can have better service differentiation capability and lower request dropping probability than the integrated service over DiffServ schemes. Furthermore, it is shown that it preserves a friendly networking environment for conventional transmission control protocol flows and maintains the simplicity feature of the DiffServ network model.     

光纤联网：开发高级业务的工具

曾被人们认为未来才会出现的有线业务，如交互VOD(视频点播)、快速因特网接入和IP电话很快就会成为今日的现实。这些业务的迅速发展对其传输渠道——光纤同轴电缆混合网(HFC)有着越来越多的需求。     

Data express gigabit junction with the next-generation Internet

Important as a very high-performance backbone is to the next generation of the Internet, it is no less important that the points at which people connect to the backbone-the so-called points of presence, or POPs-provide an equivalent level of performance. For almost three years, members of the academic, research, and business community in the North Carolina region known as the Research Triangle-the area lying amid the cities of Raleigh, Durham, and Chapel Hill-have been working to create a high-performance regional network. As partners in the North Carolina Network Initiative (NCNI), they have built a network that can serve as a POP handling the multigigabit traffic to be delivered by the next-generation Internet. Thence comes its name: a GigaPOP. Like a great railway junction, the GigaPOP is a central distribution point where huge amounts of digital freight are moved between various end points and the main line (such as the very high-performance Backbone Network Services, or VBNS). The NCNI is one of a handful of regional networking organizations around the country. The others include the California Research and Education Network 2 (Calren2), the Metropolitan REN (MREN) serving the Chicago area, the Houston Area Computational Science Consortium (HACSC), and the New York State Educational and Research Network (Nysernet). NCNI's work, which predates most initiatives for the Internet's second generation, serves as a model of how various regions can latch onto the coming information superhighway to good effect     

Statistical multiplexing and QoS provisioning for real-time trafficon wireless downlinks

Quality of service (QoS) provisioning in wireless networks involves accounting for the statistical fluctuations in the wireless channel quality, in addition to the traffic variability of interest in a purely wireline setting. We consider providing QoS to packetized, delay-constrained (real-time) applications over a Rayleigh-faded wireless downlink. Since the wireless medium is prone to high error rates with typically correlated errors, it is essential to use some kind of link-layer error-recovery mechanism to provide the desired level of reliability. We call this procedure of converting a link with frequent and correlated errors into a near-lossless packet pipe “link shaping.” The link-shaping scheme considered in this paper exploits the natural interleaving provided by packet-by-packet transmissions to different mobiles to break up the error correlations due to Rayleigh fading and employs forward error correction (FEC) coding on the interleaved data. In addition to considering static (peak-rate) bandwidth sharing as in conventional wireless downlinks, we propose mechanisms for statistical multiplexing of traffic, which lead to substantial capacity gains. For example, for 13 kb/s voice sources over a 1-Mb/s link, we obtain a two-fold capacity gain over static (peak-rate) bandwidth allocation     

Schedulability analysis of real-time traffic in WorldFIP networks: an integrated approach

The WorldFIP protocol is one of the profiles that constitute the European fieldbus standard EN-50170. It is particularly well suited to be used in distributed computer-controlled systems where a set of process variables must be shared among network devices. To cope with the real-time requirements of such systems, the protocol provides communication services based on the exchange of periodic and aperiodic identified variables. The periodic exchanges have the highest priority and are executed at run time according to a cyclic schedule. Therefore, the respective schedulability can be determined at pre-run-time when building the schedule table. Concerning the aperiodic exchanges, the situation is different since their priority is lower and they are bandied according to a first-come-first-served policy. In this paper, a response-time-based schedulability analysis for the real-time traffic is presented. Such analysis considers both types of traffic in an integrated way, according to their priorities. Furthermore, a fixed-priorities-based policy is also used to schedule the periodic traffic. The proposed analysis represents an improvement relative to previous work and it can be evaluated online as part of a traffic online admission control. This feature is of particular importance when a planning scheduler is used, instead of the typical offline static scheduler, to allow online changes to the set of periodic process variables.     

光互联网:重画网络蓝图

多业务网络模型的演进过程中,显然一直存在着两种对立的模型,即面向连接的技术（采用带外信令）和无连接的技术。无论哪一种模型都没有试图解决可靠性、可扩展性以及保证提供服务质量（QoS）的基本问题。我们面临的挑战是如何实现动态互动、平滑过渡和分布智能。解决方法和策略一直在变化,其中包括演进的QoS模型、创新的复用技术、综合分组/光的策略,以及不断增加的可扩展性产品,但是每种方法都有其优点和缺点。自从上一世纪90年代末以来,光技术已经大举进入运营商的网络。光学系统能否最终替换分组交换技术？答案似乎很清楚：这些…     

Wireless communications and networking: an overview

This paper presents an overview of wireless local-area networks (LANs) and wireless personal area networks (PANS), with emphasis on the two most popular standards: IEEE 802.11, and Bluetooth. While there are many such surveys in the current literature and online, we attempt here to present wireless LANs and PANS in a unified fashion as a viable alternative to wired LANs, while stressing the remaining challenges and limitations     

High-capacity multiservice optical label switching for the next-generation Internet

This article presents an optical label switching technology geared toward the next-generation Internet, and highlights its promising potential to accommodate packet, burst, and circuit traffic in a unified optical layer. In particular, we provide detailed discussions on an architecture design for a high capacity optical label switching router by considering enabling optical technologies. In pursuit of an effective contention resolution scheme, we investigate an end-to-end solution by incorporating a traffic shaping function at the network edge with wavelength, time, and space dimensions contention resolution in the core network. Experimental results indicate that this scheme is capable of achieving very low packet loss rates. Furthermore, due to its natural compatibility with GMPLS architecture, optical label switching has great potential for a seamless upgrade of today's optical networks toward the next generation Internet.