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

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

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)

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

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

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

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

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

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)

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

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

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

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

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.

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

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

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

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

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:

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

Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-21 Traditional Internet Applications Electronic Mail ( ) –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

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

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

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

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)

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

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

Copyright © 2012 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4-28 TCP/IP Protocol Suite Transport Layer –TCP (for 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

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