1. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Chapter 2 Networking Basics

2. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Network Definition A network is a system of interconnected objects or people. There are many different types of networks. A computer network is defined as having two or more devices such as workstations, printers, and servers linked together for the purpose of sharing information.

3. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 A Typical Computer Network

4. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Computer Networks Using Voice Cable Telephone lines are often used for transmitting data between computers, particularly for home and small business Internet users. Although this is a slow connection method, it is fairly inexpensive, and for many home users, the only option available. New telco (short for telephone company) data services are bringing higher bandwidths at reasonable costs to home and small business users over the same copper wires that carry voice calls.

5. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Goals of the Network Simple Manageable Adaptable and scalable Reliable Transparent The network should be:

6. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Benefits of Networking Sharing Output Devices - Printers, other output devices, and fax machines can be shared. Sharing Input Devices - High-end devices are typically used occasionally and are often expensive so it makes sense to configure them for multiple users on the network. Sharing Storage Devices - Files can be saved on these storage devices and accessed from anywhere on the network.

7. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 More Benefits of Networking Sharing Internet Connections - With the proper software, an entire LAN can connect to the Internet through one phone line and a single ISP account. Security – It is much easier to secure data and resources when policies and enforcement are centralized and managed. Sharing Data and Applications - Sharing data files result in the efficient use of disk space and easier collaboration on multi-user projects.

8. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Role of cabling in a network In the past, data and voice networks were separate. Today, the wiring systems are integrated creating organized and standards- driven structured cabling systems. Such systems pull wires for both data and voice networks at the same time, sometimes even using the same kind of wiring for both.

9. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Networking media The most common networking medium is copper wiring, which uses electrical current to send signals. Fiber-optic cable uses pulses of light to transmit signals along thin strands of glass. Wireless media include radio waves, infrared, or microwave waves.

10. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Server Location Issues One feature of any structured cabling installation is the ability to provide services from any location on the network. Peer-to-peer networks have no central server. Every network member shares files with every other member. Servers contain information or applications that can be accessed by many users.

11. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Types of Computer Networks A local area network (LAN) is a computer network that connects a cluster of users and devices within a building and is managed on site. Multiple LANs can be internetworked together to form Building Area Networks (BANs) or Metropolitan Area Networks (MANs). LANs, BANs, and MANs can be internetworked together over large geographical regions to form Wide Area Networks (WANs).

12. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Global and regional voice networks The telephone system is a global network allowing users from virtually anywhere in the world to call another user. The global telephone network is composed of smaller telephone networks from each country.

13. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Local voice network A localized voice network is basically a private telephone network confined to an organization. These are called private branch exchanges (PBXs), and are found in many large organizations. PBXs allow users to access other users on the network by only dialing their extension rather than the entire phone number. Users of the PBX share a certain number of outside lines for making telephone calls external to the PBX.

14. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Local Area Networks A computer network that connects users and devices within a building or campus and is managed on site is called a Local-Area Network (LAN). LANs are found in businesses, schools, governments, and even homes.

15. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Metropolitan Area Networks When two or more LANs are linked within a city or limited geographic area, it is called a metropolitan-area network (MAN).

16. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Wide Area Networks A wide-area network (WAN) has few geographic limits. WANs can cover a city, country, or even the entire world. The Internet is an example of a WAN.

17. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Network topologies Computer networks have physical and logical topologies. Physical topologies are the layout of the networking cables, devices, and workstations. Logical topologies dictate the path data takes between devices and workstations. Every network has both a logical and a physical topology.

18. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Physical Topologies Physical topologies describe the actual physical layout of the network.

19. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 The Bus Topology A physical bus topology uses a single length of cable that runs from one end of the network to the other. Users are connected to the central cable by segments of cable.

20. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Ring and Dual Ring Topologies In a physical ring topology, all devices are connected by a circle of wire. The dual-ring topology provides additional reliability since it has two pathways for traffic to flow. Ring Dual Ring

21. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 The Star and Extended Star Topology A star topology connects all cables to a central point. An extended star topology is created by linking together several star topologies to a central point. Ring Star Extended Star

22. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 The Hierarchical Topology The hierarchical topology imposes order on the network by grouping hosts based on their physical location on the network. Hierarchical

23. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Mesh Topology A mesh topology provides redundancy for a network by connecting each host to every other host. Mesh

24. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 The OSI reference model The OSI reference model is used universally as a method for teaching and understanding network functionality. Following the OSI model when designing, building, upgrading, or troubleshooting will achieve greater compatibility and interoperability between various types of network technologies.

25. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 The OSI reference model

26. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Reasons for using the OSI model Divides the aspects of network operation into less complex elements. Enables engineers to specialize design and development efforts on specific functions. Prevents changes in one area from affecting other areas, so that each area can evolve more quickly. Allows network designers to choose the right networking devices and functions for that layer. Helps with testing and troubleshooting.

27. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Physical layer (Layer 1) This layer provides the electrical, mechanical, procedural, and functional means for activating and maintaining whatever physical link exists between hosts. If the link between hosts or networks is severed or experiencing problems, data may not transmit. Networking media such as twisted-pair, coaxial, and fiber-optic cable are layer 1 equipment.

28. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Data-link layer (Layer 2) This layer deals with speed of transmission, flow control, error identification, and topology. This layer recognizes special identifiers that are unique to each computer, called media access control (MAC) addresses.

29. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Network layer (Layer 3) The network layer adds logical or network addresses, such as Internet Protocol (IP) addresses to information that passes through it. With the addition of this information, the frames are now called packets. This layer is responsible for determining the best way to move data from one network to another. Routers perform this operation and are thus referred to as Layer 3 devices.

30. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Transport layer (Layer 4) This layer takes the data file and divides it up into segments to facilitate transmission. This layer is also responsible for reliable delivery of data between the two hosts.

31. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Session layer (Layer 5) The session layer establishes, maintains, and manages conversations, called sessions, between two or more applications on different computers. The session layer is involved in keeping the lines open for the duration of the session and disconnecting them at the conclusion.

32. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Presentation layer (Layer 6) This layer provides formatting services to the application layer by ensuring the data that arrives from another computer can be used by an application. For instance, it translates EBCDIC characters from mainframe computers into ASCII characters for PCs so that an application can read the data. This layer is also responsible for encryption and compression.

33. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Application layer (Layer 7) The main function of the application layer is to provide network services to the end user. These network services include file access, applications, and printing.

34. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Layer 1 problems When there are problems with a network, troubleshooting should begin with Layer 1. It is estimated that about three-quarters of all network problems are Layer 1 problems. Many of these could be avoided when installing cable.

35. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Data-link Layer Functions Data-link layer (Layer 2) LAN devices help filter network traffic by looking at the MAC addresses in the frame. These MAC addresses are physical addresses burned into the network interface cards (NICs) on PCs and devices. The data-link layer devices use these addresses when performing their functions.

36. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Bridges A bridge keeps a table with all MAC addresses on the network. This table enables the bridge to recognize which MAC addresses are on each side of the bridge. A bridge works by keeping traffic destined for one side of the bridge to that side alone.

37. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Switches A switch can divide the network into many subnetworks or smaller networks depending on the number of ports on the switch. A switch helps to keep network communications from reaching beyond where they are destined. A switch allows multiple connections within it. When two hosts are communicating, they use only a pair of ports.

38. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Network Layer Functions The network layer (Layer 3) deals with higher- level addressing schemes and path determination. The network layer address is the Internet Protocol (IP) address of a computer. Each computer on a network has an IP address to identify its location on the network. It indicates to which network and subnetwork a computer belongs.

39. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Routers A router is a Layer 3 networking device that connects network segments or entire networks. It is considered more intelligent than Layer 2 devices because it makes decisions based on information received about the network as a whole. A router examines the IP address of the destination computer to determine which path is best to take to reach the destination.

40. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Transport Layer Functions The transport layer (Layer 4) is responsible for segmenting the data file and regulating the flow of information from source to destination. This end-to-end control is provided using a variety of techniques, such as sequence numbers, acknowledgements, and windowing.

41. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Session Layer Functions The session layer (Layer 5) is responsible for managing the transmission session. The session layer sets up, maintains, and then terminates sessions between hosts on the network.

42. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Presentation Layer Functions The presentation layer (Layer 6) facilitates communication between applications on diverse computer systems to occur in such a way that it is transparent to the applications. It does so by reformatting the data.

43. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 Application layer functions The application layer (Layer 7) does not provide services to any other OSI layer. It provides services to applications used by the end user.

44. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 OSI Model Review Layer 1

45. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 OSI Model Review Layer 2

46. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 OSI Model Review Layer 3

47. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 OSI Model Review Layer 4

48. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 OSI Model Review Layer 5

49. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 OSI Model Review Layer 6

50. Cisco Networking Academy ProgramCopyright 2003Fundamentals of Voice and Data Cabling 1.2 OSI Model Review Layer 7