Networking

1. Networking

2. What is a Network?

3. What is a Network? • A network consists of 2 or more computers connected together, and they can communicate and share resources (e.g. information)

4. Why Networking? • Sharing information — i.e. data communication • Do you prefer these? • Or this?

5. Sharing hardware or software • E.g. print document • Centralize administration and support • E.g. Internet-based, so everyone can access the same administrative or support application from their PCs

6. NIC and modem • A modem, or modulator-demodulator, is a device that provides the computer with connectivity to a telephone line. • Converts signals from analog to digital, and digital to analog. • Depending upon your “Internet connection”, you may have just a NIC, just a modem or both.

7. Kinds of Networks? • Depending on one’s perspective, we can classify networks in different ways • Based on transmission media: • Wired (UTP, coaxial cables, fiber-optic cables) and Wireless

8. Wireless Networks Types • There are two main types of wireless networks: • Ad hoc – also known as peer-to-peer or IBSS (Independent Basic Service Set) – An ad hoc wireless network is when at least two devices such as two computers have wireless NICs. • Infrastructure – Wireless network that connects multiple wireless network devices through an Access Point.

9. Kinds of Networks? • Based on network size: • LAN and WAN (and MAN)

10. Interconnecting LANs and WANs To the Internet To offsite LANs • Host systems usually connect into a LAN switch • Number of hosts limited by the number of ports on the switch • Routers have two main uses • Interconnecting LANs • Connecting to a WAN or to the Internet • Routers interconnect LANs • To separate the users • To separate the traffic switch router

11. LAN and WAN • Local Area Network (LAN) • Small network, short distance • A room, a floor, a building • Limited by no. of computers and distance covered • Usually one kind of technology throughout the LAN • Serve a department within an organization • Examples: • Network inside the Student Computer Room • Network inside Laboratory • Network inside your home

12. Wide Area Network (WAN) • A network that uses long-range telecommunication links to connect 2 or more LANs/computers housed in different places far apart. • Towns, states, countries • Examples: • Network of our Campus • Internet Your home WAN USA Student Computer Centre

13. Example WAN technologies: • ISDN – Integrated Service Digital Network • Basic rate: 192 Kbps Primary rate: 1.544Mbps • T-Carriers― basically digital phone lines • T1: 1.544Mbps T3: 28T1 • Frame relay • Each link offers 1.544Mbps or even higher • ATM – Asynchronous Transfer Mode • Support B-ISDN: 155Mbps or 622Mbps or higher • SONET – Synchronous Optical Network • Basic rate OC1: 51.84Mbps • Support OC12 and up to OC192 (9953.28Mbps) or even higher in the future

14. Example of WAN: Broadband Cable Network • Cable TV services have been extensively developed in most modern cities • Cable TV companies try to make use of their coaxial cable installed (that are supposed to carry TV signals) to deliver broadband data services • Many cable network wiring has been replaced with hybrid fiber-coax (HFC) ― i.e. use of fiber-optic cable to connect to the subscribers’ buildings, and then the original coaxial cable to connect to each household

15. The connection is shared by a number of subscribers, hence may raise performance and security problems PC TV Fiber-optic cable Cable Drop Coaxial Cable Cable company

16. Kinds of Networks? Based on management method • Peer-to-peer and Client/Server

17. Server-Based Network – A basic type of LAN wherein users login to a controlling computer, called a server and is more secure. The server contains information about who can connect to the network and to what shared resources. It also provides some of these resources. These networks normally consist of 10 or more computers. • Peer-to-Peer Network – One of two basic types of LANs wherein each computer user acts as a server. Each computer stores password and sharing information for its own resources. Usually has fewer than 10 computers. • NOS (Network Operating System) – Special operating system on a server containing utilities for managing users, resources, and security.

18. Peer-to-Peer Networks • Peer-to-peer network is also called workgroup • No hierarchy among computers  all are equal • No administrator responsible for the network Peer-to-peer

19. Peer-to Peer Network

20. Advantages of peer-to-peer networks: • Low cost • Simple to configure • User has full accessibility of the computer • Disadvantages of peer-to-peer networks: • May have duplication in resources • Difficult to uphold security policy • Difficult to handle uneven loading • Where peer-to-peer network is appropriate: • 10 or less users • No specialized services required • Security is not an issue • Only limited growth in the foreseeable future

21. Clients and Servers • Network Clients(Workstation) • Computers that request network resources or services • Network Servers • Computers that manage and provide network resources and services to clients • Usually have more processing power, memory and hard disk space than clients • Run Network Operating System that can manage not only data, but also users, groups, security, and applications on the network • Servers often have a more stringent requirement on its performance and reliability

22. Server-Based Network

23. Advantages of client/server networks • Facilitate resource sharing – centrally administrate and control • Facilitate system backup and improve fault tolerance • Enhance security – only administrator can have access to Server • Support more users – difficult to achieve with peer-to-peer networks • Disadvantages of client/server networks • High cost for Servers • Need expert to configure the network • Introduce a single point of failure to the system

24. Kinds of Networks? • Based on topology (connectivity): Bus, Star, Ring …

25. Topology Hub • How so many computers are connected together? • Bus TopologyRing Topology • Star Topology

26. Hub/Switch

27. Star Topology

28. Ring Topology

29. Bus Topology

30. TCP/IP description and configuration • Transmission Control Protocol/Internet Protocol (TCP/IP) is a set of protocols or rules developed to allow cooperating computers to share resources across a network. • Includes a “unique” (well, not always) address assigned to your computer

31. Verify IP Configuration: Win XP, NT, 2000 3 1 • ipconfig • ipconfig /all 2

32. Verify IP Configuration: Win 9x 2 1 3 4

33. TCP/IP description and configuration

34. Testing connectivity with ping • The ping command works by sending multiple IP packets to a specified destination. Each packet sent is a request for a reply. • The ping command is used to test the NIC transmit/receive function, the TCP/IP configuration, and network connectivity.

35. Network Management • Network management is the process of controlling a complex data network to maximize its efficiency and productivity • The overall goal of network management is to help with the complexity of a data network and to ensure that data can go across it with maximum efficiency and transparency to the users

36. Network Management • The International Organization for Standardization (ISO) Network Management Forum divided network management into five functional areas: • Fault Management • Configuration Management • Security Management • Performance Management • Accounting Management

37. Fault Management • Is the process of locating problems, or faults, on the data network • It involves the following steps: • Discover the problem • Isolate the problem • Fix the problem (if possible)

38. Fault Management: Activities • Trace (Monitor) & Identify Faults (Abnormal Operation) • Accept Facts &Act on Error-Detection Notification • Carry Out Sequences of Diagnostic Tests • Correct Faults • Maintain and Examine Error Logs

39. Fault Management: Summary • Alarm (Categories / Priorities) • Response (Repair / Clear Alarm) • Recording (Report)

40. Configuration Management • The configuration of certain network devices controls the behavior of the data network • Configuration management is the process of finding and setting up (configuring) these critical devices

41. Configuration Management: Summary • Continuous Information Collection • Detection of Changes • Scheduling Resource Provisioningin Response to Changes

42. Security Management • Is the process of controlling access to information on the data network • Provides a way to monitor access points and records information on a periodic basis • Provides audit trails and sounds alarms for security breaches

43. Security Management • Security Management is more than locking server rooms or insisting on password discipline. • Security Management is the process of managing a defined level of security on information and IT services • SecurityManagement is a part of every manager’s job. Management is responsible for taking appropriate measures to reduce the chances of failure to an acceptable level.

44. Security Management: Activities • Access Management (Users / Use) • Detection of Attacks (Against Information) • Protection Measures (Encryption)

45. Threats to Network Security • Viruses: Computer programs written by devious programmers and designed to replicate themselves and infect computers when triggered by a specific event. • Trojan Horse Program: Delivery vehicles for destructive code, which appear to be harmless or useful software program. • Vandals: Software applications or applets that cause destruction.

46. Threats to Network Security • Attacks: Including reconnaissance attacks (information-gathering activities to collect data that is later used to compromise networks); access attacks (which exploit network vulnerabilities in order to gain entry to e-mail, databases, or the corporate networks); and denial-of-service attacks (which prevent access to part or all of computer system) • Data Interception: Involves eavesdropping on communications or altering data packets being transmitted

47. Threats to Network Security • Social Engineering: Obtaining confidential network security information through nontechnical means, such as posing as technical support person and asking for people’s passwords.

48. Network Security Tools • Antivirus Software Packages: This packages counter most virus threats if regularly updated and correctly maintained. • Secure Network Infrastructure: Switches and Routers have hardware and software features tat support secure connectivity, perimeter security, intrusion protection, identity services, and security management. • Virtual Private Networks: These networks provide access control and data encryption between two different computers on a network.

49. Network Security Tools • Identity Services: These services help to identify users and control their activities and transactions on the network. • Encryption: Encryption ensures that messages cannot be intercepted or read by anyone other than the authorized recipient. • Security Management: This is the glue that holds together the other building blocks of a strong security solutions.

50. Performance Management • Involves measuring the performance of the network hardware, software, and media • Examples of measured activities are: • Overall throughput • Percentage utilization • Error rates • Response time