Chapter Topics Part 1. Network Definitions. Behind the Scenes: Networking and Security

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Chapter Topics Part 1 Behind the Scenes: Networking and Security CS10001 Computer Literacy Business Networks Network Advantages Client/Server Networks Network Classifications Servers Toplogies

1 Chapter Topics Part 1 Behind the Scenes: Networking and Security CS10001 Computer Literacy Business Networks Network Advantages Client/Server Networks Network Classifications Servers Toplogies Chapter 12: Networking and Security (Behind the Scenes) 1 Chapter 12: Networking and Security (Behind the Scenes) 2 Network Definitions Network Advantages Network Two or more nodes connected so that data, information and resources are shared P2P Peers communicate in a decentralized manner ( < 10 nodes) Client/server Commonly associated with large business systems ( > 10 nodes) Chapter 12: Networking and Security (Behind the Scenes) 3 Increases productivity Sharing data and information Sharing peripherals Efficient communication Enables expensive resource sharing Eliminates the need for idle peripherals (printers) Generates cost savings because idle resources do not waste money Chapter 12: Networking and Security (Behind the Scenes) 4 1

Network Advantages Network Advantages Enables software sharing Eliminates the need for the same program on each computer (replaced by software license) Eliminates having to install new software on

2 Network Advantages Network Advantages Enables software sharing Eliminates the need for the same program on each computer (replaced by software license) Eliminates having to install new software on each machine (save time and space) Provides Internet connectivity sharing Eliminates dedicated connections for each computer Reduces expenses for Internet service Provides centralized operation With network administrators Maintain network integrity Allows for seamless transfer with new software installation or when new peripherals are added Chapter 12: Networking and Security (Behind the Scenes) 5 Chapter 12: Networking and Security (Behind the Scenes) 6 Client/server Networks Recall that servers are computers that provide access to network resources. Client computers request the network resources. Peripherals Software Storage space Advantages of Server-based Networks Data flows efficiently Large number of requests satisfied simultaneously Configured for specific requests or services Centralized security and data backups Scalable Add nodes without affecting other nodes Add servers without disruption of service Chapter 12: Networking and Security (Behind the Scenes) 7 Chapter 12: Networking and Security (Behind the Scenes) 8 2

3 Network Classifications Network Classifications Classified by size and physical distances LANs Local area network Small geographic area Example is computer lab on campus Chapter 12: Networking and Security (Behind the Scenes) 9 WANs Wide area network Example is a university-wide connection of labs MANs Metropolitan area network Example is linking city or county computers Chapter 12: Networking and Security (Behind the Scenes) 10 Network Classifications PANs Personal area networks Wireless and operate within personal operating space (within 30 of individual) Intranet Private corporation networks (groupware) Inaccessible from the outside world (firewalls) Chapter 12: Networking and Security (Behind the Scenes) 11 There are six main components in server-based networks Servers Computers functioning with one purpose Network topologies Layouts and structures of complex networks Transmission media Cable or wireless technology based on respective topology Chapter 12: Networking and Security (Behind the Scenes) 12 3

4 There are six main components in server-based networks cont d. Network operating system (NOS) software Installed on both the server and all computers Network adapters Installed on the network devices to enable communication Network navigation devices Needed to transport the network signal Chapter 12: Networking and Security (Behind the Scenes) 13 Servers Three main types of servers 1. Dedicated Perform only one function 2. Authentication Keep track of logins and available services 3. File Stores and manages files (seen with student accounts at a university) Does this sound familiar? Chapter 12: Networking and Security (Behind the Scenes) 14 Servers Common dedicated servers Print servers Manages client-requested printing of jobs Creates print queue (prioritizes print jobs) Frees up CPU time on individual computers Application servers Provides access to software not installed on the client s s computer Acts as a application software repository Chapter 12: Networking and Security (Behind the Scenes) 15 Servers Common dedicated servers Database servers Provides clients with access to database information servers Processes and delivers incoming and outgoing Communication servers Provides single-point access to the Internet Web servers Hosts web pages using specialized server software Chapter 12: Networking and Security (Behind the Scenes) 16 4

5 Terminator Bus topology All the nodes are connected in a linear sequence on a single cable. Terminator Bus topology cont d. Commonly used in P2P networks, not server-based networks s communicate directly with each other An access method coordinates the communication nodes nodes listen before transmitting Data collisions may occur easily Chapter 12: Networking and Security (Behind the Scenes) 17 Chapter 12: Networking and Security (Behind the Scenes) 18 Bus topology cont d. Data is broken down into packets and the nodes just move the data along (passive topology) When the media is clear, the transmitting node broadcasts to all other nodes When a node hears data addressed to it, the data is taken off the media and processed by that node Media is capped off by terminators that absorb the signal Chapter 12: Networking and Security (Behind the Scenes) 19 Bus topology cont d. Advantages Advantages Low cost Simplicity Disadvantages Signal disruption if cable breaks Hard to expand because of degrading signal Performance affected with large additions of nodes Chapter 12: Networking and Security (Behind the Scenes) 20 5

6 Ring topology Token Ring topology cont d. Data flows in one direction in a special packet or token (token-ring topology) s grab the token to transmit data and release it when finished Receiving nodes send acknowledgments The access method avoids data collisions Chapter 12: Networking and Security (Behind the Scenes) 21 Chapter 12: Networking and Security (Behind the Scenes) 22 Ring topology cont d. An active topology because each node has certain responsibilities passing passing the token Allows for fairer allocation of resources chatty nodes must pass the token Supports a large number of users but adding a node interrupts the network failure also interrupts the network Star topology Switch Chapter 12: Networking and Security (Behind the Scenes) 23 Chapter 12: Networking and Security (Behind the Scenes) 24 6

7 Star topology cont d. An Ethernet-based topology Widely deployed and most flexible of all client/server networks s are connected to a central switch The switch manages the data transmission All nodes examine the transmission but only pick up data addressed to them Star topology cont d. Uses an access method called CSMA/CD (Carrier Sense Multiple Access with Collision Detection) s listen before transmitting data Data collisions may happen Jam signals notify nodes a collision occurred and a random time-out is called Chapter 12: Networking and Security (Behind the Scenes) 25 Chapter 12: Networking and Security (Behind the Scenes) 26 Star topology cont d. More expensive and more complex failure does not interrupt the network Supports large number of users Addition of nodes does not interrupt service Switch centralizes communication and offers a troubleshooting point An active topology Chapter 12: Networking and Security (Behind the Scenes) 27 Chapter Topics Part 2 cont d. Transmission Media Network Operating System (NOS) Network Adapters Network Navigation Devices Network Security Digging Deeper: The OSI Model Chapter 12: Networking and Security (Behind the Scenes) 28 7

8 Transmission Media Recall that nodes on the network are connected by transmission media P2P networks incorporate existing wiring (phone or electric), cable and wireless Business networks mainly use cable Twisted pair Coaxial Fiber optic Chapter 12: Networking and Security (Behind the Scenes) 29 Transmission Media Considerations when choosing cable Maximum run length Bandwidth Bend radius or flexibility Cable cost Installation costs Susceptibility to interference Signal transmission methods Chapter 12: Networking and Security (Behind the Scenes) 30 Transmission Media Types of cable Twisted pair (UTP) Telephone line Coaxial Television cable Fiber-optic Glass or plastic Transmission Media Business networks use a combination of cables based on the following: Topologies Run lengths Presence of interference Need for wireless connectivity Chapter 12: Networking and Security (Behind the Scenes) 31 Chapter 12: Networking and Security (Behind the Scenes) 32 8

9 NOS This specialized software enables the communication between nodes Facilitates server services Controls network communication Manages peripherals and storage Provides the protocol (special rules) followed by the clients and server Network Adapters Critical functions of network adapters Enable network transmission by converting digital signals to high-powered signals that travel the network Break up data into packets for network travel and reassemble them for the recipient Control and guard data passed to clients Chapter 12: Networking and Security (Behind the Scenes) 33 Chapter 12: Networking and Security (Behind the Scenes) 34 Navigation Devices Recall that data is passed along the network in the form of packets Recall that a node receives packets addressed to it (based on topology) How are addresses assigned to nodes? Chapter 12: Networking and Security (Behind the Scenes) 35 Navigation Devices MAC addresses Media Access Control addresses Physically located on the network adapters (like VIN for vehicles) Allows for internal addressing within a network Allows for frame bundling by the NOS Chapter 12: Networking and Security (Behind the Scenes) 36 9

10 Navigation Devices Switches are used to move data transmissions inside a network Examples: LAN or Star topology Uses MAC addresses Routers are used to move data transmissions between networks Example: LAN to Internet Uses IP addressing (discussed later) Chapter 12: Networking and Security (Behind the Scenes) 37 Network Security Common security threats (SAs( list) Human error Malicious human activity Natural events or disasters Handled in different ways Authentication Access privileges Physical protection Firewalls Chapter 12: Networking and Security (Behind the Scenes) 38 Network Security - Authentication For network access a userid and password are required Periodically protected by password changes Failed attempts or brute force attacks cause network lockouts Prevents hackers from account access Network Security Access Privileges Account setup grants access to certain parts of the network Based on the status of the client Prevents unauthorized changes to files on the network Chapter 12: Networking and Security (Behind the Scenes) 39 Chapter 12: Networking and Security (Behind the Scenes) 40 10

11 Network Security Physical Protection Measures Locked rooms to protect servers and network equipment (routers, switches) Swipe cards to track access Biometrics to uniquely identify humans Network Security Firewalls Packet screening by routers on incoming and outgoing mail (IP address checks) Bastion servers are not on the internal network but secure the perimeter Proxy servers direct links outside the network Chapter 12: Networking and Security (Behind the Scenes) 41 Chapter 12: Networking and Security (Behind the Scenes) 42 Dig Deeper: The OSI Model OSI Model: Open Systems Interconnection Developed by the IEEE Gives protocol guidelines to the NOS Communication tasks are divided into layers Layers provide more efficient communication and interacts with layers above and below Chapter 12: Networking and Security (Behind the Scenes) 43 The OSI Model Layers Application Layer Interacts between application software and the network Formats the data for the Presentation layer Presentation Layer Performs data encryption if specified Reformats the data for the Session layer Chapter 12: Networking and Security (Behind the Scenes) 44 11

12 The OSI Model Layers Session Layer Sets up and manages a virtual connection between sender and receiver Tracks transmission until all data is sent Transport Layer Breaks up data into packets and sequences them Handles acknowledgment of packets Chapter 12: Networking and Security (Behind the Scenes) 45 The OSI Model Layers Network Layer Examines packet address Determines best route for transfer Data Link Layer Assembles data into frames Addresses the frames Passes the frames to the Physical layer Chapter 12: Networking and Security (Behind the Scenes) 46 The OSI Model Layers Physical Layer Converts data into a signal Transmits the data Delivers the data to the final destination Chapter 12: Networking and Security (Behind the Scenes) 47 12

Technology in Action. Chapter 12 Behind the Scenes: Networking and Security. Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall

Technology in Action. Chapter 12 Behind the Scenes: Networking and Security. Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall Technology in Action Chapter 12 Behind the Scenes: Networking and Security 1 Networking Advantages Networks Increase productivity Enable the sharing of hardware resources Facilitate knowledge sharing Enable