信息通信网络概论课件：Chapter 1 Communication Networks and Services

1、Chapter 1 Communication Networks and Services,1.1 Evolution of Network Architecture and Services 1.1.1 Telegraph Networks and Message Switching 1.1.2 Telephone Networks and Circuit Switching 1.1.3 The Internet, Computer Networks, and Packet Switching 1.2 Future Network Architecture and Their Service

2、s 1.3 Key Factors in Communication Network Evolution 1.3.1 Role of Technology 1.3.2 Role of Regulation 1.3.3 Role of the Market 1.3.4 Role of standards,1.1 Evolution of Network Architecture and Services,A communication network, a set of equipment and facilities: Telephone network: bidirectional tran

3、sfer of voice signals Telegraphy network Broadcast network Cellular network；femtocell Internet, and so on. The design of a network is influenced by the services that it supports,1.1 Evolution of Network Architecture and Services,How and in what form information is transferred? Telegraph networks and

4、 message switching Telephone networks and circuit switching The Internet, Computer networks, and Packet switching,1.1.1 Telegraph networks and message switching,In 1837 Morse telegraph Message dots and dashes short and long pulses (digital communication) In 1851 networks of telegraph stations routin

5、g, address, store-and-forward, message switching routing, address, store-and-forwarding base of computer networks transmission rate, multiplexing, ASCII code, modulation basis for todays modems In 1901 Marconi, long-distance wireless radio communication,1.1.1 Telegraph networks and message switching

6、,1.1.1 Telegraph networks and message switching,Architecture of telegraph network: digital transmission, dot and dash, zero and one, wire, wireless or smoke signal framing, grouping the sequence of dots/dashes or zeros/ones into characters and messages address, routing,1.1.2 Telephone networks and c

7、ircuit switching,In 1876 Bell, telephone, two-way, real time, simple, analog transmission originally In 1878 telephone switches were introduced. L=N(N-1)/2 if N=1000, L = 499500(lines),1.1.2 Telephone networks and circuit switching,The telephone switch has three phases: setup, maintain and transfer,

8、 release,1.1.2 Telephone networks and circuit switching,In 1890s automated electromechanical switches were invented, hierarchical network,1.1.2 Telephone networks and circuit switching,Telephone numbering system: for dialing connection Connection-oriented: need a connection for the transfer of infor

9、mation Circuit switch: the transfer mode that involves setting up a dedicated end-to-end connection Only in the setup phase the routing decision is made,1.1.2 Telephone networks and circuit switching,Analog to digital and computerizing In 1948 the transistor was invented. In 1960s integrated circuit

10、s, leading to voice carried in a digital transmission system. PCM. T-1(1.5mbps) with the multiplexing of 24 PCM signals in 1962. analog switch. In the early 1980s digital switches were deployed. User to the network is only analog technology. In the 1960s and 1970s switch was computerized, leading to

11、 a separate signaling network. It enabled the introduce of new services such as cellular telephone service etc.,1.1.2 Telephone networks and circuit switching,The characteristics of the telephone network: transmission system, analog or digital telephone switch, end-to-end a telephone numbering syste

12、m user-to-network signaling system routing It is noteworthy that the control part of the telephone network, the signaling system, involves computer communication.,1.1.3 The Internet, Computer Networks, and Packet Switching,The Internet is based of TCP/IP, datagram service. The development of compute

13、r network: SAGE from 1950 to 1956, 23 computer networks. SABRE in 1964, airline reservation system. Early computers were extremely expensive tree-topology, terminal-oriented networks in 1960s. dumb terminals. the ARPANET interconnected firstly computers over a wide area. intelligent computers. the I

14、nternet, In late 1970s TCP/IP emerged, basis for todays Internet, IP over everything.,1.1.3 The Internet, Computer Networks, and Packet Switching, 1969 ARPANET 1974 First paper on packet switching 1983 TCP/IP implementation 1985 NSFNET 1986 First router 1991 WWW 1995 US commercial Internet 1996 US N

15、ext Generation Internet-,1.1.3 The Internet, Computer Networks, and Packet Switching,Protocol: a set of rules that governs how two or more communicating parties are to interact. Including: - message exchange - Event action - Time sequence when certain messages are transmitted and received. *Computer

16、s communication protocols must be precise and unambiguous.,Protocol Elements,Syntax （语法）= How to Say? Semantic（语义）=Whats the meaning? Synchronization（同步）=Do what?,1.1.3 The Internet, Computer Networks, and Packet Switching,Terminal-oriented networks,1.1.3 The Internet, Computer Networks, and Packet

17、Switching,* Medium access control sharing a multi-drop line,1.1.3 The Internet, Computer Networks, and Packet Switching,* Statistical multiplexer/concentrators: Framing, header, address, error-control, CRC multiplexer systems,1.1.3 The Internet, Computer Networks, and Packet Switching,A example of t

18、erminal-oriented networks: circa 1970,1.1.3 The Internet, Computer Networks, and Packet Switching,Architecture of terminal-oriented: A digital transmission system Framing , address, error control and the boundaries of a frame Medium access control,1.1.3 The Internet, Computer Networks, and Packet Sw

19、itching,Computer-to-computer networks: packet-switching networks A packet is a variable-length block of info. maximum size segmented multiple packets reassembled ,1.1.3 The Internet, Computer Networks, and Packet Switching,The ARPANET: In the 1960s, computer networks, packet switching, WAN. The comm

20、unication lines were leased from public carriers. 56kbps digital transmission, up to 8000bits in length, message segment and reassemble connectionless service, destination address info in packet for routing, each packet switch contains a routing table, packetframe, error control, a time for frame re

21、transmission, distributed routing algorithm, routing table updated in response to changes in traffic or topology,1.1.3 The Internet, Computer Networks, and Packet Switching,The ARPANET:,1.1.3 The Internet, Computer Networks, and Packet Switching,The ARPANET: buffering, end-to-end congestion control,

22、 flow control, multiple user applications, e-mail, remote login, file transfer The ARPANET was the first large-scale wide-area packet-switching network. It provided for the transfer of messages between host computers using connectionless packet switching network. Its architecture incorporated most o

23、f the elements of modern packet switching networks,1.1.3 The Internet, Computer Networks, and Packet Switching,Local area networks limited distances, share resource, low cost, very high speed, relatively error-free, the NIC a globally unique address and messages broadcast. MAC( medium access control

24、), a variety of topology including ring, bus, tree etc. the Ethernet is the most successful LAN,1.1.3 The Internet, Computer Networks, and Packet Switching,The Ethernet: a) bus topology b) star topology,1.1.3 The Internet, Computer Networks, and Packet Switching,The Ethernet: CSMA/CD carrier sensing

25、 multiple-point access/collision detect the bus topology the star topology, coaxial cable hub The elements of LAN: high speed digital transmission system, unique address frame, mac supporting broadcasting,1.1.3 The Internet, Computer Networks, and Packet Switching,The Internet: in the mid-1970s afte

26、r the ARPANET, for communications across multiple, possibly dissimilar, networks. an internetwork or internet:,The Internet Protocols,1、The Internet Protocol (IP) : datagram, the IP packet switches are called gateways or routers. best-effort service, simplicity in networks, complexity on terminals h

27、ierachical address space, 4bytes, dotted-decimal notation, network ID and host ID, DNS 2、UDP and TCP user datagram protocol, transmission control protocol connectionless-oriented, connection-oriented exist only on terminals,1.1.3 The Internet, Computer Networks, and Packet Switching,3、the applicatio

28、ns SMTP for e-mail, FTP for file transfer, HTTP for web service, RTP for real-time transfer, etc. base of TCP/IP, two advantages: 1) work over the entire Internet, 2) no effect on the underlying network technology change,1.1.3 The Internet, Computer Networks, and Packet Switching,The key elements of

29、 the Internet: logically linked together by a global unique space based on the IP communication using TCP/IP suite or other IP-compatible protocol high-level services layered on the communication and related infrastructure NOTE: use TCP/IP and a private address space is referred to as an internet (w

30、ith lowercase i),ESSENTIAL ELEMENT OF A NETWORK ARCHITECTURE,Digital transmission for binary info Framing, delineation, error-control Medium access control Addresses Routing table in packet switches for exchange of packets Dynamic calculation of routing table Congestion control Internetworking by us

31、ing gateways or routers Segmentation and reassembly, end-to-end error recovery A multiplicity of applications,ESSENTIAL ELEMENT OF A NETWORK ARCHITECTURE,Note: The above elements can be organized in a layered fashion. Two fundamentally approaches to communication: Connectionless: no connection needs

32、 to be set up ahead of time. telegram and datagram Connection-oriented: a connection needs to be set up before info can be transferred. Telephone and ATM,1.2 FUTURE NETWORK ARCHITECTURES AND THEIR SERVICES,Telephone-centric to computer-centric networks New applications and services network evolution

33、 The Internet provides a simple but powerful service. Any application through the exchange of messages Multimedia info affects networks evolution today New protocols in the Internet manage traffic flow and establish paths for IP packets to provide delay guarantees,1.3 KEY FACTORS IN COMMUNICATION NETWORK EVOLUTION,A new telecommunications service shall satisfy with three conditions: The technology: cost-effective Government regulations: admittance The market: exist Addition: standards,1.3 KEY FACTORS IN COMMUNICATION NETWORK EVOLUTION,Technology, regulation, marke