Week2-Networking For Amin and Troubleshooting (1).pptx

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Networking for Administrators & Troubleshooting Presented by : Dr. Oraib AbuAlganam Systems Administration I 1 Objectives. 1. What is Networking? 2. Network Components: Hardware and Software. 3. OSI and TCP/IP Models. 4. Client Serve...

Networking for Administrators & Troubleshooting Presented by : Dr. Oraib AbuAlganam Systems Administration I 1 Objectives. 1. What is Networking? 2. Network Components: Hardware and Software. 3. OSI and TCP/IP Models. 4. Client Server and Peer to Peer Network Models. 5. Types of Networks: LAN, MAN, and WAN. 6. Troubleshooting Network Issues. Systems Administration I 2 After studying this lecture you will be able to-  Explain computer networks.  Discuss the need of network in today's world.  State the advantages of network.  Describe Client Server Model, and explain different types of networks.  Explain the issues, key aspects, and importance of network troubleshooting. Systems Administration I 3 What is networking? Networking refers to interconnected computing devices that can exchange data and share resources with each other.  Networking involves the use of hardware and software components to establish and maintain connection. - Hardware component: network devices such as hub, switches, routers, etc.. - Software component: Network Protocols and Operating System. Systems Administration I 4 Main Network Components 1. The hardware components Systems Administration I 5 Network Interface Cards (NIC)  Connects one computer to another computer over a network.  The unique MAC address of the device is coded into the NIC.  Types of NICs: Wired NIC and Wireless NIC. Systems Administration I 6  These devices are used to form a network.  Difference: is in how they handle data traffic within a network? 2. HUB Systems Administration I 7 How Hub works?  Connects 4 computers.  Broadcasts data all computers connected to it.  It is a repeater.  It is a layer 1 device.  Do not deal with MAC or IP address. Systems Administration I 8 Disadvantages of the HUB 1. Security concerns: All the information is available to each connected device, which can expose sensitive data to unauthorized users. 2. Unnecessary traffic: it creates unnecessary traffic on the network leading to limited bandwidth. 3. Hub is a half duplex. For the above reasons hub is considered as an old technology, and switches replace hub Systems Administration I 9 Switch  Switch connects multiple devices to create a network. It has a number of ports.  A switch is more intelligent than a hub.  It deals with MAC address. It operates on layer 2. Systems Administration I 10  Switches use MAC address in a frame to make forwarding decisions.  A MAC address (media access control address) is a 12-digit hexadecimal number assigned to each device connected to the network.  Example: A MAC address of 2c549188c9e3 is typically displayed as 2C:54:91:88:C9:E3 or 2c-54-91- 88-c9-e3 Systems Administration I 11 Advantages of the Switch 1. Fast detection for the device. 2. Layer 2 device (data link layer). 3. Full duplex. 4. Save Bandwidth. 5. Increased security. Systems Administration I 12 Router  While a network switch can connect multiple devices and networks to expand the LAN.  It cannot perform the task of transferring data between the internal network and other external networks. Systems Administration I 13 Therefore, to connect two or more local area networks to the internet you need a ROUTER. A router is a device that connects two or more packet-switched networks or subnetworks. It serves two primary functions: managing traffic between these networks by forwarding data packets to their intended IP addresses.  It deals with IP addresses.  It is a Network Layer device.  It receives and forwards packets from network to network.  Router is responsible for routing network packets by determining the best route possible, by using its own routing table. Systems Administration I 14 Types of Routers 1. Edge Routers: An edge router is a device that connects an internal network to the internet. 2. Core Routers: A core router is a type of router designed to operate in the internet backbone, or core. It carries out routing functions to transmit data packets from one network to another as a Gateway router or just a gateway. An edge router is a device that connects an internal network to the internet. Systems Administration I 15 Systems Administration I 16 Bridge  Different LANs in a network can be linked to build a bigger LAN. This kind of network aggregation is known as network bridging. The bridge links many LANs so that they seem to be a single network. Systems Administration I 17 Modem Short for modulator/demodulator. It Functions as a way to connect to the internet over a telephone line. Types of Modem: 1. External: An external modem is a network device that is in a self-contained enclosure external to a computer. 2. Internal: An Internal Modem is a device that allows a computer to transmit data over telephone or cable lines. 3. Wireless: It transmits and receives signals over the air. External Modem Systems Administration I 18 Cables  Network cables serve as a physical communication route between multiple computers and network components. They let computers communicate, connect, and transmit data and information.  The most used cables for guided transmission of signals: 1. Coaxial Cable. 2. Twisted Pair Cable 3. Fiber-Optic Cable. Systems Administration I 19 Network Servers  A server is a computer or system that provides resources, data, services, or programs to other computers, known as clients, over a network  Manage the resources of the network.  Responsible for serving all the requests made by the clients on the network.  Examples: Web server, Mail server, database server, virtual machine server, Domain name system (DNS) server, Print server, etc.  In week 4, 10, 11 we will talk in detail about Web server, Email server, etc. as shown in the syllabus. Systems Administration I 20 Network Software Components Network Software components include the Protocols and the Network Operating System (NOS). Network OS  Network Operating System is a computer operating system that facilitates to connect and communicate various independent computers over a network.  independent computer that has its own local memory, hardware, and O.S.  The Network O.S. Runs on the sever.  The NOS is the brain of the server. Examples of NOS: UNIX/Linux, MacOS, and the Microsoft family of Windows Servers are examples of client/server network operating systems. Systems Administration I 21 Functions of the Network Operating System NOS 1. Controlling access to resource on the network. 2. Creating and managing user accounts on the network. 3. Monitor and troubleshoot the network Systems Administration I 22 Network Protocols Protocol − A protocol is a rule or guideline followed by each computer for data communication. Protocol model is a set of related protocols that are laid down for computer networks. The two popular protocol models are − 1. OSI Model ( Open System Interconnections). 2. TCP / IP Model. Systems Administration I 23 OSI Model: OSI stands for Open Systems Interconnection. Why was the OSI model created?  Diverse computer networking methods.  Standardizing a networking system: One vendor’s solution was not compatible with another vendor’s solution.  It is used as a reference model. OSI has 7 layers Physical layer, Data Link layer, Network layer, Transport layer, Session layer, Presentation layer, and Application layer. Each layer performs its task independently. It was developed in 1984 by the International Organization for Standardization (ISO). Systems Administration I 24 OSI Model Systems Administration I 25 Data Encapsulation Protocol Data Units As application data is passed down the protocol stack on its way to be transmitted across the network media, various protocol information is added at each level. This is known as the encapsulation process. The form that a piece of data takes at any layer is called a Protocol Data Unit (PDU). During encapsulation, each succeeding layer encapsulates the PDU that it receives from the layer above in accordance with the protocol being used. At each stage of the process, a PDU has a different name to reflect its new functions. Note: Although the UDP PDU is called datagram, IP packets are sometimes also referred to as IP datagrams. Systems Administration I 26 Systems Administration I 27 Data Encapsulation Three Addresses Network protocols require addresses to be used for network communication. The OSI transport, network, and data link layers use addressing in some form. The transport layer uses protocol addresses in the form of port numbers to identify network applications. The network layer specifies addresses that identify the networks that clients and servers are attached to. Data link layer specifies the devices on the local LAN that should handle data frames. All three addresses are required for client-server communication. Systems Administration I 28 TCP/IP Model  TCP/IP stands for Transmission Control Protocol/Internet Protocol.  The TCP/IP model is a summarized version of the OSI model.  It has 4 layers named as Physical layer, Network layer, Transport layer, and Application layer. It also can be used as a communications protocol in a private computer network. Systems Administration I 29 Systems Administration I 30 5. Client Server & Peer to Peer Network Models Based on the access and data processing, computer network can be divided into: 1. Peer to Peer Model. 2. Client-Server Network. Peer to Peer Network Model Definition of P2P: A P2P (peer to peer) network is a decentralized collection of computers that has been established to exchange information and sharing resources (such as file documents, songs, movies, software, etc.) with certain users.  All computers are equals.  No centralized management.  Windows XP, 10 in function in peer to peer environment.  Examples of P2P networ: small office, single department. Systems Administration I 31 -Laptop A, computer A, computer B, and computer C are peers. -A peer is any computer that participates in a network and has the same functionality as one or more computers in the network. -Individual users have responsibility over who can access data and resources on their computers, and what resources can be accessed by the other users. # All computers are equals. #No centralized management (NO server) # Each computer runs its own OS such as window XP, win 10, Linux, etc. #Examples of P2P network: small office, single department. Systems Administration I 32 Advantages of peer-to-peer network  Server is not required - reduces the load and cost of server(s).  No full-time system administrator is required.  If a single computer goes down, the others continue as normal. Disadvantages of peer-to peer network  Data is vulnerable.  Slow performance. Systems Administration I 33 Client-Server Network Model  A client-server network is a communications architecture in which clients receive resources and services from a dedicated host over a local area network (LAN) or a wide-area network (WAN), such as the Internet.  A client-server network has clients (workstations) as well as a server (or many servers).  It is a centralized network. Systems Administration I 34 Advantages of client –server network  Centralization: You always gain centralize administration (we will discuss “centralization” in week 3 – Active directory.  Security: data is properly safeguarded.  The client-server model is also very scalable.  Management: easy to manage files.  Accessibility: client can log into the system.  Can work in big environments. Systems Administration I 35 Disadvantages of client server network  Increased cost: Cost of the system is more compared to peer-to peer networks.  Maintenance: When the servers are implemented, it is going to work non-stop. Which means it must be given proper attention.  Robustness: As we all know client server networks are centralized. In case if the main server happens to undergo failure, then the whole network will be disrupted. Therefore, client server networks lacks on the side of robustness. Systems Administration I 36 Networks of Many Sizes Small Home Networks – connect a few computers to each other and the Internet. Small Office and Home Office (SOHO) – enables computer within a home, office or remote office to connect to a corporate network, or access centralized, Small Home SOHO shared resources. Medium to Large Networks – can have many locations with hundreds or thousands of interconnected computers. World Wide Networks – connects hundreds of millions of computers world-wide – such as the internet. Medium/Large World Wide Systems Administration I 37 Network Topologies LANs and WANs Network infrastructures vary greatly in terms of: Size of the area covered Number of users connected Number and types of services available Area of responsibility The two most common types of network infrastructures are Local Area Networks (LANs) Wide Area Networks (WANs) LANs connected to a WAN Systems Administration I 38 Network Topologies LANs and WANs (Contd.) A LAN is a network infrastructure that A WAN is a network infrastructure that spans a small geographical area. spans a wide geographical area. LAN WAN Interconnect end devices in a limited area. Interconnect LANs over wide geographical areas. Administered by a single organization or individual. Typically administered by multiple service providers. Provide high-speed bandwidth to internal end devices and Typically provide slower speed links between LANs. intermediary devices. Systems Administration I 39 Enterprise LAN Enterprises typically use the same technology as SOHO LANs but on a larger scale. There might be hundreds or thousands of devices connected to the network that is located in one or multiple buildings. Here’s an example : Systems Administration I 40 Metropolitan Area Network (MAN) The main purpose of a MAN is to connect different LANs in a city to share resources and exchange data, as well as to provide internet access to users. A MAN typically covers a geographic area of several kilometers and is larger than a LAN but smaller than a WAN. Systems Administration I 41 Larger networks with two buildings might look like this: Systems Administration I 42 Introduction to Troubleshooting Network Issues What does network troubleshooting mean? Network troubleshooting refers to the process of identifying, diagnosing, and resolving issues or problems within a computer network.  Connectivity problems: 1- Error messages indicating “device not found” or that the connection has timed out. 2- Inability to communicate with devices located in the cloud (or over the internet), on the same network, and even in the same subnet.  Performance problems: slow performance.  Security problems: Worms and viruses, Abuse of account privileges  Errors: Monitors all system errors and critical system messages Systems Administration I 43 What is the Importance of Effective Network Troubleshooting? Effective network troubleshooting is critically important for several reasons:  Minimizing Downtime: downtime can result in financial losses and damage to reputation. Troubleshooting helps minimize downtime and ensures business continuity.  Cost Reduction: Effective troubleshooting reduces the time and resources required to resolve problems, thus saving money.  Optimizing Performance: Ensuring that network resources are used efficiently and that users experience minimal latency.  Security: Troubleshooting can help detect and mitigate security threats, protecting sensitive data and systems. Systems Administration I 44 Key aspects of what network troubleshooting requires  Issue Identification: The first step is recognizing that there is a problem.  Problem Isolation: Once the problem is identified, troubleshooting involves decreasing down the scope of the issue to determine where it originates.  Root Cause Analysis: To address network issues effectively, it's essential to identify the underlying cause or causes.  Testing and Verification: Troubleshooting involves running tests and checks to confirm the suspected causes and to verify that the proposed solutions work as expected.  Documentation: recording the symptoms, diagnostic steps taken, and solutions applied. Documentation helps in future reference. Systems Administration I 45 Examples of Network Monitoring and Management Tools Here are some examples of network monitoring and management tools:  Wireshark: A widely-used network protocol analyzer that allows you to capture and inspect data packets traveling through a network. It's valuable for diagnosing network issues and security analysis.  Nagios: An open-source network monitoring and alerting system that provides comprehensive monitoring of network devices, services, and system metrics. It sends alerts when issues are detected.  Nmap (Network Mapper): A free and open-source utility for network discovery and security auditing. It can be used to discover hosts and services on a network. Systems Administration I 46 Systems Administration I 47

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