1. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Chapter 4: Networking and the Internet Computer Science: An Overview Eleventh Edition by J. Glenn Brookshear

2. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-2 Chapter 4: Networking and the Internet 4.1 Network Fundamentals 4.2 The Internet 4.4 Internet Protocols

3. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-3 Network Classifications Scope –Local area network (LAN) –Metropolitan area (MAN) –Wide area network (WAN) Ownership –Closed versus open Topology (configuration) –Bus (Ethernet) –Star (Wireless networks with central Access Point)

4. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-4 Figure 4.1 Network topologies

5. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-5 Figure 4.1 Network topologies (continued)

6. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-6 Protocols CSMA/CD –Used in Ethernet –Silent bus provides right to introduce new message CSMA/CA –Used in WiFi –Hidden terminal problem

7. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-7 Figure 4.2 Communication over a bus network

8. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-8 Figure 4.3 The hidden terminal problem

9. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-9 Connecting Networks Repeater: Extends a network Bridge: Connects two compatible networks Switch: Connect several compatible networks  The existence of the above three devices is transparent to the individual computers. Router: Connects two incompatible networks resulting in a network of networks called an internet (convert between the idiosyncrasies)

10. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-10 Figure 4.4 Building a large bus network from smaller ones

11. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-11 Figure 4.5 Routers connecting two WiFi networks and an Ethernet network to form an internet

12. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-12 Inter-process Communication Client-server –One server, many clients –Server must execute continuously –Client initiates communication Peer-to-peer (P2P) –Two processes communicating as equals –Peer processes can be short-lived

13. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-13 Figure 4.6 The client/server model compared to the peer-to-peer model

14. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-14 The Internet The Internet: An internet that spans the world –Original goal was to develop a means of connecting networks that would not be disrupted by local disasters. –Today it has shifted from an academic research project to a commercial undertaking.

15. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-15 Internet Architecture Domain: A portion of the Internet that is a network or internet controlled by a single authority –Connected to the rest of the Internet (the cloud) by a router called a gateway Internet Corporation for Assigned Names & Numbers (ICANN): Oversees the registration of domains

16. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-16 Figure 4.7 A typical approach to connecting to the Internet

17. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-17 Internet Architecture Internet Service Provider (ISP) –Tier-1 –Tier-2 Access ISP: Provides connectivity to the Internet –Traditional telephone (dial up connection) –Cable connections –DSL –Wireless

18. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-18 Figure 4.7 Internet Composition

19. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-19 Internet Addressing: IP Addresses IP address: 32 bit identifier for a machine (currently being expanded to a 128 bit system) –Network identifier: Assigned by ICANN –Host address: Assigned by domain administrator Dotted decimal notation: Common notation for displaying IP addresses –Example: 192.207.177.133

20. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-20 Internet Addressing: Host Names Mnemonic address made up of two parts: –Domain name Assigned by a registrar Example: aw.com Top level domain: Classification of domain owner –By usage – Example:.com = commercial –By country – Example:.au = Australia –Subdomains and individual host names Assigned by domain owner Example: r2d2.compsci.nowhereu.edu Translation between mnemonic addresses and IP addresses handled by name servers

21. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-21 Traditional Internet Applications Electronic Mail (email) –Domain mail server collects incoming mail and transmits outing mail –Mail server delivers collected incoming mail to clients via POP3 or IMAP File Transfer Protocol (FTP) Telnet and SSH

22. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-22 More Recent Applications Voice Over IP (VoIP) Internet Radio –N-unicast –Multicast

23. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-23 Figure 4.12 Package-shipping example

24. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-24 Internet Software Layers Application: Constructs message with address –Software units that use Internet communication to carry out their tasks –Mnemonic addresses -> IP addresses Transport: Chops message into packets –Messages are properly formatted: divide long messages into small segments –Sequence numbers for segment reassembly –These segments are treated as individual, unrelated message pieces

25. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-25 Internet Software Layers Network: Handles routing through the Internet –Routing: decide in which direction a packet should be sent at each step Maintaining forwarding table Link: Handles actual transmission of packets –Transferring the packet Dealing with the communication details (CSMA/CD for Ethernet; CSMA/CA for WiFi)

26. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-26 Figure 4.13 The Internet software layers

27. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-27 Figure 4.14 Following a message through the Internet Note: Only the link and network layers in routers Using port numbers to determine application units

28. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-28 TCP/IP Protocol Suite Transport Layer –TCP (for email service) Connection-oriented: establishing a connection (i.e., sending a control message) before sending a message Reliable: acknowledgment and packet retransmissions Flow control and congestion control –UDP (for VoIP service) Network Layer –IP (IPv4 and IPv6) Forwarding: relaying packets through the Internet Routing: updating forwarding table to reflect changing conditions

29. Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-29 Figure 4.15 Choosing between TCP and UDP