Enterprise Networks II: Wide Area Networks

Early data networks were based on point‐to‐point or multipoint topologies. They were often of a star structure with a central processing unit (CPU) at the star's hub. Terminals in this network were “dumb” terminals and relied on the CPU's processing power for nearly all network activity.When the personal computer (PC) gained wide acceptance, distributed processing became the rule. As a result, data networks and data networking became much more complex. We now see complex multiple star, mesh, and tree like networks where many of the nodes have multiple inlets and outlets.Data rates were based on the limitations of the analog network. In the period of the 2nd edition of this book, this roughly equated to 9600 bps. Today, it is common to have 56‐kbps access lines to a larger network where the basic channel data rate is 64 kbps. We can bring together these basic building blocks of 64 kbps to form aggregate channels of 128, 256, and 384 kbps up to 1.536 Mbps or 1.984 Mbps.Data protocols instilled order out of contentious chaos in data network operation. These protocols, applying to wide area networks (WANs), are the principal thrust of the chapter. Most are based on shipping user data in packets or frames. We discuss the transport of user data in cells in Chapter 28.Most packet networks are based on CCITT Rec.X.25. If we widen the definition of packet networks to include the transmission control protocol/internet protocol (TCP/IP), certainly X.25 will have a competitor. Both TCP/IP and X.25 have a comparatively high latency (latencyis the time it takes from initiation to completion of a data transaction). Frame relay was introduced in the same period. This is a comparatively low latency system.This section provides design data and brief descriptions of wide area data networking as a whole with hypothetical reference circuits, the archetypical data link layer protocol, high‐level data link control (HDLC), X.25 and its companion, link access protocol B‐layer (LAPB), TCP/IP family of protocols, frame relay family of protocols, and a brief description of SMDS (switched multimegabit data service). Variants of LAPD are discussed in the frame relay section of this chapter.

In previous chapters, the local applications and services of UNIX in individual computers have been introduced. This chapter will present the remote and network functions and services of UNIX in servers and workstations. After explanation of general concepts about the Internet and computer networking, Transmission Control Protocol/Internet Protocol (TCP/IP) suit will be presented, and contents associated with layers of TCP/IP model from down to up will be discussed. Finally, we will explain how to use some commands in the application layer of the TCP/IP model, such as telnet, ping, ftp, etc.

Virtual networks (VNets, in Azure), maintain the same characteristics as physical networks. The processes of physical networks enable data from one computer to be transported over Transmission Control Protocol, Internet Protocol (TCP/IP) to another computer. The information, or data, is transformed so that TCP/IP packets can transport it efficiently; it is sent to another computer through hardware network interface cards (NICs) via physical network switches. To send the data to and from other buildings and other datacenters, network engineers use hardware devices referred to as gateways. Additionally, in datacenters today, the hardware provides network architects with the ability to virtualize physical networks or subnetworks () into a virtual network subnet called a . How would your budget be improved if Azure VNets reduced the need for a considerable amount of physical networking equipment?

As an important component of ship navigation and monitoring system, communication software integrates the functions of data acquisition, communication and display into a whole, and is the key links of intelligent maritime transportation. Based on TCP/IP (Transmission Control Protocol / Internet Protocol) protocol, communication procedure between server and clients is introduced with sequence diagram and activity diagram of object-oriented design descriptions. Server side of the software utilizes multithread technology to achieve network communication with transfer center of the communications operator and client, and finishes the functions of data acquisition and parsing. At the same time, client side of the software establishes connections with server and parses receiving real time binary data to display in data grid. In the process of installation and debugging, problems of client breakdown and asynchronous data between server and clients and less data in the clients are solved.

Products in brief

Chapter 3 - The Internet and TCP/IP

One of the main communication protocols used for transmitting PMU data packets are Transmission Control Protocol/ Internet Protocol (TCP/IP) and User Datagram Protocol/Internet protocol (UDP/IP). This paper aims at presenting the implementation and simulation of a communication network for wide area monitoring system. The main purpose is to send real data recorded from PMUs over communication network using both protocols and compare their performance in terms of data transmission reliability.

Telemedicine is the use of Information and Communication Technology (ICT) in health ecosystem with a provision of visual communication, patient data transfer & collaborative learning. Government of India is actively taking initiatives for establishing digital high-speed internet connectivity though National Knowledge Network (NKN), State Wide Application Network (SWAN) & National Optical Fiber Network (NOFN) to super-specialist center, medical colleges, research organizations, Primary Health Center (PHC)/ Community Health Center (CHCs) up to block level and panchayat levels. Wellness centers and ‘DigiGaon’ bring digital inclusion and it enables people in rural areas to be able to access services like telemedicine and skill enhancement with the use of digital technologies. High-speed fiber-optic based internet bandwidth has deployed under NKN in as many as 250 medical colleges around the country. Many medical institutions have migrated to NKN to enhance their capacity of telemedicine activity using telemedicine platform funded by central and state government agencies. Majority of telemedicine in India funded by Ministry of Health & Family Welfare (MOH&FW) for interlinking Medical Colleges across the country with the purpose of education and National Rural Telemedicine Network (NRTN) for Healthcare delivery under National Health Mission (NHM), National Medical College Network (NMCN) and other public private partnership (PPP) models. Medical super-specialty institutes for the National Resource Centers (NRCs) and Regional Resource Centers (RRCs) for NMCN has defined and medical colleges will soon link to RRCs. India has diversified geographical region with availability of variable bandwidth in different part. Remote PHC/CHCs located outside city has bandwidth issue whereas majority of medical hospitals in the city has high-speed internet bandwidth. Video solutions given by hardware vendors and software vendors needs to be collaborate centrally which enables users to connect even with lower bandwidth or with the use of high-speed broadband (HSB) mobile dongle. It increases the reach to the remotest place in India through any of the available platform (Desktop, H.323 device, Android or IOS smart phone etc). Recording and streaming integration with video collaboration enhances the purpose of sharing the medical educational content during or after e-CME/ workshops/ seminars with remote doctors. Entire collaboration solution thus need direct content sharing, mobility, recording and reporting with support for multiple input sources from cameras, X-Ray, CT-SCAN, fundus camera, ultrasonography etc. Broadcast link needs to share simultaneously to multiple users and connectivity thus follow confidentiality, security and traceability with the usage of video firewall in data center. Traffic routed from outside the institute needs to convert in local IP pool through port address translation called Network Address Translation (NAT) for allowing traffic from known protocols like Internet Control Message Protocol (ICMP), Transmission Control Protocol/ Internet Protocol (TCP/IP) and User Datagram Protocol (UDP). The video collaboration telemedicine infrastructure were created at STBMI, SGPGIMS, Lucknow internetworking with Integrated Operation Theatre for live sharing, Medical Telepresence Room for sharing live surgical skill during workshop, e-Tumour Board for discussion between multiple specialties departments from different hospitals, 3D Lecture Theater for sharing medical CMEs created for sharing knowledge resources with networked institutions.

4 - Packet Technologies

Many smart healthcare centers are deploying long distance, high bandwidth networks in their computer network infrastructure and operation. Transmission control protocol (TCP) is responsible for reliable and secure communication of data in these medial infrastructure networks. TCP is reliable and secure due to its congestion control mechanism, which is responsible for detecting and reacting to the congestion in the network. Many TCP congestion control mechanisms have been developed previously for different operating systems. TCP CUBIC, TCP Compound, and TCP Fusion are the default congestion control mechanism in Linux, Microsoft Windows, and Sun Solaris operating systems, respectively. The earliest congestion control mechanism Standard TCP acts as the trademark congestion control mechanism. The exponential growth of congestion window ( $cwnd$ ) in slow start phase of the TCP CUBIC causes burst losses of packets, and TCP flows did not share available link bandwidth fairly. The prime aim of this paper is to enhance the performance of TCP CUBIC for long distance, high bandwidth secured networks to achieve better performance in medical infrastructure, concerning packet loss rate, protocol fairness, and convergence time. In this paper, congestion control module for slow start is proposed, which reduces the effect of the exponential growth of $cwnd$ by designing the new limits of $cwnd$ size in slow start phase, which in turn decreases the packet loss rate in healthcare networks. NS-2 is used to simulate the experiments of enhanced TCP CUBIC and state-of-the-art congestion control mechanisms. Results show that the performance of enhanced TCP CUBIC outperforms by 18% as compared with the state-of-the-art congestion control mechanisms.

Named data networking (NDN) is a new and promising Internet architecture, which aims to replace the current transmission control protocol/Internet protocol (TCP/IP)-based Internet. The NDN internet architecture has introduced several benefits in numerous applications. An NDN-based indoor positioning and navigation system can further optimize existing localization technologies with reduced the server load and faster response time. In this study, an NDN-based approach for the existing Wi-Fi fingerprinting-based indoor positioning and navigation was investigated. Among the many features of NDN, the network-level caching can reduce the computational load and response time of the localization and navigation server. The theoretical analysis of the runtime complexity shows that the NDN's network-level caching performance is better than those of the conventional algorithms. In this paper, naming methods for different services and a server-side algorithm for handling the NDN requests are proposed. The real-world implantation and testing results show a better overall performance than that of TCP/IP. This network-level optimization for indoor positioning and navigation opens new opportunities because it can be combined with other application-level optimization techniques for more efficient indoor positioning and navigation in the future.

Chapter 12 - Frame Relay

The transmission of huge amounts of data generated from various sensors is the basis and prerequisite for the analysis and prediction of the marine ecosystem. The special geographical conditions of the ocean determine that its data transmission is different from the common terrestrial data transmission. In this study, a marine environmental monitoring network architecture is proposed to collect environmental data from marine ecosystems using a heterogeneous network constructed by a multi-hop network and a satellite network. Considering the characteristics of satellite networks, such as high bandwidth delay product (BDP), long latency and high bit error rate, this work proposes a transmission scheme that improves the transmission performance of Transmission Control Protocol/Internet Protocol (TCP/IP)-based Internet networks over satellite networks. The improved scheme increases the monitoring data transmission rate, distinguishes between random data loss and congested data loss, rationalizes the threshold in fast recovery, and improves the overall transmission performance of the marine environmental monitoring network. The experimental results show that the proposed scheme can greatly improve the transmission performance of the monitoring network compared with traditional transmission protocols. The network model proposed in this study makes full use of current advanced network technologies, including multi-hop networks, wireless sensor networks, and satellite networks to expand the monitoring area at sea. This study provides a useful reference for the network model and data transmission for ocean monitoring.

Westnet

The authors begin with a discussion of the criteria for evaluating wide-area networks (WANs) used to interconnect remote bridges. Then they assess various WANs, point out the advantages of frame relaying, and describes this experience with operating implementation interconnecting token-rings via a prototype frame relay. The quality of a bridge service is considered to be the quality of MAC (media access control) service as seen by end-stations on different LANs that are bridged either directly by a single bridge or indirectly via multiple bridges and associated LANs. It depends critically on the route (which is dependent on the network topology) between the source and destination LANs and the quality of service provided by the individual brides and, in the case of remote bridges, WANs along the route.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>