ch01_Introduction to Computer Networks - Updated - short.pptx

Information Technology Department Introduction to Computer Networks CIT231 Introduction to Computer Networks E-TextBook : Guide to Networking Essencials, Edition: 8th , Greg Tomsho, Cengage, ISBN...

Information Technology Department Introduction to Computer Networks CIT231 Introduction to Computer Networks E-TextBook : Guide to Networking Essencials, Edition: 8th , Greg Tomsho, Cengage, ISBN: 978-0-3571-1828-3 CLO1. Explain the basic concepts of computer networks and data communication.. Faculty of Engineering and Computing  OutLine Describe basic computer components and operation Explain the fundamentals of network communication Defi ne common networking terms Compare different network models 2  The Fundamentals of Network Communication A computer network consists of two or more computers connected by some kind of transmission medium Such as a cable or air waves In order to access the Internet, a computer has to be able to connect to a network The next few slides will cover what is required to turn a standalone computer into a networked computer Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Network Components (1 of 2) Hardware components needed to turn a stand-alone computer into a networked computer: Network interface card is an add-on card plugged into a motherboard expansion slot that provides a connection between the computer and the network Network medium is a cable that plugs into the NIC and makes the connection between a computer and the rest of the network Network media can also be the air waves, as in wireless networks Interconnecting device allows two or more computers to communicate on the network without having to be connected directly to one another Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Network Components (2 of 2) Network software can be divided into the following categories: 1. Network clients and servers Network client software requests information stored on another network computer or device Network server software allows a computer to share its resources 2. Protocols Network protocols define the rules and formats a computer must use when sending information across the network 3. NIC drive NIC drivers receives data from protocols and forwards this data to the physical NIC Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Steps of Network Communication 1. Application tries to access a network resource by sending a message 2. Client software formats the message and passes the message on to the network protocol 3. Protocol packages the message in a format suitable for the network and sends it to the NIC driver 4. NIC driver sends data in the request to the NIC card to be converted into necessary signals to be transmitted on the network Steps taken at the server side are essentially the reverse of those on the client side Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Layers of the Network Communication Process (1 of 2) Each step required for a client to access network resources is referred to as a “layer” Each layer has a task and all layers work together Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Layers of the Network Communication Process (2 of 2) Step Description Layer 1 An application tries to access a network resource. User application 2 Client software detects the attempt to access the Network client or server network and passes the message on to the software network protocol. 3 The protocol packages the message in a format Network protocol suitable for the network and sends it to the NIC driver. 4 The NIC driver sends the data in the request to the Network interface NIC, which converts the data into the necessary signals to be transmitted across the network medium. Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  How Two Computers Communicate on a LAN: Some Details (1 of 2) TCP/IP is the most common protocol (language) used on networks TCP/IP uses 2 addresses to identify devices Logical address (IP address) Physical address (MAC address) Just as a mail person needs an address to deliver mail, TCP/IP needs an address in order to deliver data to the correct device on a network Think of the Logical address as a zip code and the Physical address as a street address Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  How Two Computers Communicate on a LAN: Some Details (2 of 2) 1. A user at Comp A types ping 10.1.1.2 at a command prompt 2. Network software creates a ping message 3. The network protocol packages the message by adding IP address of sending and destination computers and acquires the destination computer’s MAC address 4. The network interface software adds MAC addresses of sending and destination computers 5. Comp B receives message, verifies that the addresses are correct and then sends a reply to Comp A using Steps 2 – 4 Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Network Terms Explained Every profession has its own language and acronyms It is essential to know the language of networks to be able to study them Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  LANs, Internetworks, WANs, and MANs (1 of 4) Local area network (LAN) is a small network, limited to a single collection of machines and connected by one or more interconnecting devices in a small geographic area An internetwork is a networked collection of LANs tied together by devices such as routers Reasons for creation: Two or more groups of users and their computers need to be logically separated but still need to communicate Number of computers in a single LAN has grown and is no longer efficient The distance between two groups of computers exceeds the capabilities of most LAN devices Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. LANs, Internetworks, WANs, and MANs (2 of 4) Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. LANs, Internetworks, WANs, and MANs (3 of 4) Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  LANs, Internetworks, WANs, and MANs (4 of 4) Wide area networks (WANs) use the services of third-party communication providers to carry network traffic from one location to another Metropolitan area networks (MANs) use WAN technologies to interconnect LANs in a specific geographic region, such as a county of city Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Internet, Intranet, and Extranet The Internet is a worldwide public internetwork Uses protocols such as TCP/IP and HTTP to transfer and view information An intranet is a private internetwork in which devices and servers are only available to those users connected to the internal network An extranet allows limited and controlled access to internal resources by outside users Intranet vs. Internet https://www.youtube.com/watch?v=Q4sPJgaf3sM Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Packets and Frames (1 of 2) Computers transfer information across networks in shorts bursts of about 1500 bytes of data Reasons data is transferred this way: Pause between bursts allows other computers to transfer data during pauses Allows the receiving computer to process received data Allows the receiving computer receive data from other computers at the same time Gives the sending computer an opportunity to receive data from other computers and perform other processing tasks If an error occurs during transmission of a large file, only the chunks of data involved in the error have to be sent again Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Packets and Frames (2 of 2) Packets Chunks of data sent across the network are usually called “packets” or “frames”, with packets being the more well-known term Packet is a chunk of data with a source and destination IP address added to it Using the U.S. mail analogy, you can look at a packet as an envelope that has had the zip code added to the address but not the street address Frames Frame is a packet with the source and destination MAC addresses added to it The packet is “framed” by the MAC addresses on one end and an error-checking code on the other The process of adding IP addresses and MAC addresses to chunks of data is called encapsulation Information added to the front of the data is called a header and information added to the end is called a trailer Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Network Models A network model defines how and where resources are shared and how access to these resources is regulated Network models fall into two major types: Peer-to-peer network – most computers function as clients or servers (no centralized control over who has access to network resources) Server-based network – certain computers take on specialized roles and function mainly as servers, and ordinary users’ machines tend to function mainly as clients https://www.youtube.com/watch?v=3qRCxu9C_AI Advantages & Disadvantages Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Server/Domain-Based Model Network Peer-to-peer network Server-based network attribute Resource Distributed among many other Centralized on one or more access desktop/client computers; makes servers; streamlines access to access to resources more complex resources Security Users control their own shared Security is managed centrally, resources and might have several sets and users have a single set of of credentials to access resources; not credentials for all shared ideal when tight security is essential resources; best when a secure environment is necessary Performance Desktop OS not tuned for resource Server OS tuned for resource sharing; access to shared resources sharing; servers are usually can be hindered by users running dedicated to providing network applications services Cost No dedicated hardware or server OS Higher upfront costs because of required, making initial costs lower; dedicated hardware and server lost productivity caused by increasing OSs; additional ongoing costs complexity can raise costs in the long for administrative support run Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Chapter Summary (1 of 2) Components needed to make a stand-alone computer a networked computer include a NIC, a network medium, and usually an interconnecting device Also client/server software, protocols, and NIC driver The layers of the network communication process can be summarized as user application, network software, network protocol, and network interface The four terms used to describe networks of different scope are LAN, Internetwork, WAN, and MAN Packets and frames are the units of data handled by different network components Packets have the source and destination IP address added and are processed by the network protocol Frames have the MAC addresses and an error code added and are processed by the network interface A client is the computer or network software that requests network data and a server is the computer or network software that makes the network data available to requesting clients A peer-to-peer network model has no centralized authority over resources while a server-based network usually uses as directory service to provide centralized resource management Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.