Dựa trên cách tiếp cận từ trên xuống thành công, khóa học Mạng máy tính được triển khai với sự nhấn mạnh ban đầu vào các mô hình lớp ứng dụng và giao diện lập trình ứng dụng, khuyến khích trải nghiệm thực hành với các giao thức và khái niệm mạng.
NETWORK TYPES AND STANDARDS (P1)
NETWORK
Computer networks connect two or more computers to share resources, exchange files, and enable electronic communication via various mediums including cables, telephone lines, radio waves, satellites, or infrared.
Figure 1 Common types of networks
1.3 benefits and constains of each
Personal area networks (PANs), such as those using Bluetooth, eliminate the need for extra wires or space Simply enable Bluetooth on two devices to begin data sharing; for instance, connect a wireless keyboard and mouse to a tablet.
Connect to many devices at a time:
Personal area networks (PANs) enable multiple devices, such as smartphones and tablets, to connect simultaneously for file sharing and other collaborative tasks.
No extra wires are needed in this type of network Also, no extra data charges are involved so PAN is an inexpensive way of communication
It is easy to use No advanced setup is required
If you use this type of data connection within 10 meters then your network is stable and reliable Secure:
This network is secured because all the devices are authorized before data sharing Third party injection and data hacking are not possible in PAN
Used in office, conference, and meetings:
Infrared technology powers common devices like TV and AC remotes Bluetooth, infrared, and other personal area networks (PANs) connect digital devices for seamless office and conference collaboration.
Synchronize data between different devices:
One person can synchronize several devices i.e download, upload and exchanging data among devices
A person can move devices as it is a wireless network and data exchange is not affected That mean PAN is portable as well
Signal range is maximum 10 meters which makes limitation for long distance sharing
As personal area network also use infrared so it can interfere with radio signals and data can be dropped
Bluetooth and infrared have a slow data transfer rate as compared to another type of networks like LAN (local area network)
In some cases, PAN uses microwave signals in some digital devices which have a bad effect on the human body like brain and heart problems may occur
Costly in terms of communication devices:
Personal area network is used in digital devices which are costly so it is another disadvantage of PAN Examples are smartphones, PDA, laptops, and digital cameras
Infrared signals travel in a straight line:
TV remote use infrared signals which have a problem that they travel in straight line So this counts another disadvantage of PAN
ADVANTAGES Simple and relatively inexpensive:
Local area networks (LANs) offer a cost-effective and flexible networking solution for organizations seeking quick, easy setup LANs enable efficient resource sharing and collaboration.
Local area networks (LANs) significantly reduce IT costs by enabling resource sharing Instead of equipping each desktop with expensive printers and scanners, a single shared device accessible to all employees via the LAN yields substantial cost savings.
The association involving client and server:
Centralized servers store data accessible to connected PCs Authorized clients easily retrieve information, such as movies and music, after logging in.
Sharing software on a LAN saves costs by eliminating the need for individual licenses per device This centralized approach allows multiple users to access a single licensed program, offering a cost-effective solution for data protection.
Centralized server storage offers enhanced security, simplified data management (updates and deletions), and granular user access control, ensuring only authorized personnel can access sensitive information.
LAN-connected systems or devices communicate directly at very high rates of speed, based on the LAN model and ethernet cabling installed The most prevalent enabled speeds are 10 Mbps,
Gigabit Ethernet technologies, such as 100 Mbps and 1000 Mbps, are rapidly advancing Cost-effective gigabit Ethernet solutions will become widely available as technology matures and mass production increases.
DISADVANTAGES The information security issue that arises:
Improper server configuration can expose data to unauthorized users, necessitating robust security policies and procedures.
Local area networks are often devised within a building or apartment complex and cannot be stretched to a bigger area
All devices may be disproportionately affected if the server fails:
If a file on the server gets heavily damaged or a hard disc crashes, all of the linked PCs will have extreme difficulty operating correctly
Installing a LAN is difficult and expensive:
It is expensive to establish a LAN since specialized software is essential to install a server
Setting up and maintaining a Local Area Network (LAN), including hardware like hubs, switches, routers, and cables, involves significant upfront costs and ongoing professional IT support External data sharing adds further complexity.
LANs suffer from slow and cumbersome file transfers from external sources, as methods like portable drives lack universal network compatibility.
Wide Area Networks (WANs) connect geographically dispersed business locations, often spanning 1000km or more Leased lines from Internet Service Providers (ISPs) facilitate communication between these branches.
Wide Area Networks (WANs) enable data sharing across multiple locations, such as connecting a head office server to branch offices This eliminates the need for separate servers for email, files, and backups, centralizing these functions and reducing costs.
NETWORK PROTOCOL
2.1 What is the network protocol
A network protocol is an established set of rules that determine how data is transmitted between different devices in the same network
Network protocols enable seamless communication between diverse connected devices, regardless of their internal differences This facilitates global digital communication, playing a critical role in modern connectivity.
Communication protocols enable diverse network devices to interconnect, facilitating processes from file transfers to internet access across analog and digital systems.
Common types of communication protocols include the following:
Automation: These protocols are used to automate different processes in both commercial and personal settings, such as in smart buildings, cloud technology or self- driving vehicles
Instant messaging: Instantaneous, text-based communications on smartphones and computers occur because of a number of different instant messaging network protocols
Routing: Routing protocols permit communication between routers and other network devices There are also routing protocols specifically for ad hoc networks
Bluetooth: Ever-popular Bluetooth devices — including headsets, smartphones and computers — work due to a variety of different Bluetooth protocols
File transfer: If you have ever moved files from one device to another, either via a physical or digital medium, you’ve used file transfer protocols (FTP)
Internet Protocol: Internet Protocol (IP) allows data to be sent between devices via the internet The internet could not operate as it currently does without IP
Network management protocols ensure optimal performance across all network devices, including computers, routers, and servers, by defining procedures for effective network operation.
The functions of network management protocols include the following:
Connection: These protocols establish and maintain stable connections between different devices on the same network
Link aggregation protocols combine multiple network connections into a single, stronger link between devices, ensuring connection stability even if one link fails.
Troubleshooting: Troubleshooting protocols allow network administrators to identify errors affecting the network, evaluate the quality of the network connection, and determine how administrators can fix any issues
Security protocols, also called cryptographic protocols, work to ensure that the network and the data sent over it are protected from unauthorized users
Common functions of security network protocols include the following:
Encryption: Encryption protocols protect data and secure areas by requiring users to input a secret key or password in order to access that information
Entity Authentication: Entity authentication protocols create a system that requires different devices or users on a network to verify their identity before accessing secure areas
Transportation: Transportation security protocols protect data while it is transported from one network device to another.
STANDARDS
The International Organization for Standardization (ISO)
The International Electrotechnical Commission (IEC)
The International Telecommunication Union (ITU)
The Joint Electron Device Engineering Council (JEDEC)
The American National Standards Institute (ANSI)
The Association for Computing Machinery (ACM)
The National Institute of Standards and Technology (NIST)
3.2 Names of the standards used
5 Application layer HTTP, HTML (Web) MPEG, H.323 (audio/video) SMTP, IMAP, POP (e-mail)
4 Transport layer TCP (Internet and LANs) SPX (Novell LANs)
3 Network layer IP (Internet and LANs) IPX (Novell LANs)
2 Data link layer Ethernet (LAN) Frame relay (WAN) T1 (MAN and WAN)
1 Physical layer RS-232C cable (LAN) Category 5 cable (LAN) V.92 (56 Kbps modem)
NETWORK TOPOLOGY, COMMUNICATION AND BAND WIDTH REQUIREMENTS (P2)
DEFINITION
Network topology refers to the geometric arrangement of links and nodes in a computing network Alternately, network topology may describe how the data is transferred between these nodes
Network topologies are categorized as physical and logical Physical topology describes the devices' physical arrangement, whereas logical topology defines the data flow path between nodes.
1.2 Difference between physical topology and logical topology
Physical Topology means the physical layout of the network Logical topology means how the network device layout will be shown and how the data will be transferred
For example − Ring, Bus, Star, and Mesh For example − Ring and Bus
In this topology, we are concerned with how data will be transferred from the actual path
This topology is concerned with the high-level representation of the data transfer
As per the requirement, we can modify the layout of the network There is no change accepted
It can affect cost, bandwidth, scalability etc It can affect data delivery
Types of physical topologies are star, mesh, bus, and ring Types of logical topologies are logical bus, and logical ring
It is an actual route concerned with transmission It is a high level representation of data flow Physical connection of the network Data path followed on the network
Figure 2 Bus Topology Diagram Pros:
Fewer cables required than Mesh and star topology
Easy to manage and expand
Easily congested on busy periods
Efficiency decreases rapidly with each added node
Data can only travel in one direction at any point in time
Figure 3 Ring Topology Diagram Pros:
Dual ring option provides continuity through redundancy
One faulty node will bring the entire network down
Requires extensive preventative maintenance and monitoring
Performance declines rapidly with each additional node
Reorganizing the network requires a full system shutdown
Figure 4 Star Topology Diagram Pros:
Easy to manage from one point – the switch
Easy to add and remove nodes
Requires specialist network hardware (the switch)
Makes the network reliant on the switch’s performance
A finite number of switch ports limits the network’s size
Figure 5 Tree Topology Diagram Pros:
Blends bus and star topologies
Suitable for middle-sized businesses
The network is dependent on the health of the root node
Larger implementations require monitoring software
Figure 6 Mesh Topology Diagram Pros:
Durable network that isn’t dependent on any one node
Suitable for high-value networks for small to middle-sized networks
Easy to identify faulty equipment
Requires a very large amount of cable
Can be difficult to secrete all the cable
Takes a long time to set up
There is a limit to the number of cables each computer can accommodate
Figure 7 Mesh Topology Diagram Pros:
Suitable for middle-sized and large organizations
Adaptable to optimize equipment use
COMMUNICATION AND BANDWIDTH
Internetworking, or network communication, uses protocols—rules and standards—enabling applications to communicate regardless of their underlying hardware or operating systems.
Network rules are allowed or blocked actions that are performed by Firewall on detecting a network connection attempt
Firewalls offer two-tiered network security: network-level protection via packet filtering rules, and application-level protection through rules governing application access to network resources.
Based on the two levels of Firewall protection, you can create:
Network packet rules, enforced by firewalls, control inbound and outbound network traffic via specific ports and protocols, regardless of the application These rules restrict network packets based on pre-defined criteria.
Application network rules restrict network activity for specific applications, considering both packet characteristics and the application's identity This allows for granular control over network filtering, enabling selective blocking or allowing of connections based on the application.
The maximum amount of data transmitted over an internet connection in a given amount of time
Bandwidth, measured in Mbps, represents the volume of data transmitted over a connection within a specific timeframe, distinct from internet speed.
Insufficient bandwidth significantly impacts VoIP and WebRTC call quality, leading to choppy audio, disruptions, and a poor user experience Adequate bandwidth is crucial for optimal performance.
NETWORKING PRICIPLES AND PROTOCOLS (M1)
NETWORKING PRINCIPLES
Circuit switching offers a dedicated, connection-oriented path for data transmission, minimizing data loss and errors However, this dedicated path wastes bandwidth during periods of low usage Its transparent nature allows senders and receivers to utilize any bit rate or framing method.
Packet switching, a connectionless service, uses no dedicated path, limiting block size but allowing flexible bandwidth utilization However, it's prone to data loss and packet misordering.
A dedicated communication channel increases the quality of communication
Data is transmitted with a fixed data rate
No waiting time at switches
Suitable for long continuous communication
A dedicated connection makes it impossible to transmit other data even if the channel is free Resources are not utilized fully
The time required to establish the physical link between the two stations is too long
A dedicated path has to be established for each connection
Circuit switching is more expensive
Even if there is no transfer of data, the link is still maintained until it is terminated by users Dedicated channels require more bandwidth
Costs are minimized to great extent Hence packet switching is a very cost-effective technique Packets are rerouted in case of any problems This ensures reliable communication
It is more efficient for data transmission because no need to establish the path
Several users can share the same channel simultaneously Therefore packet switching makes use of available bandwidth efficiently
In packet switching, the network can not be used in applications requiring very little delay and higher quality of service
Protocols used in the packet switching are complex
If the network becomes overloaded, packets are delayed or discarded, or dropped This leads to the retransmission of lost packets by the sender
It is not secured if security protocols are not used during packet transmission.
PROTOCOLS
2.1 How protocols enable networked systems
Network protocols modularize complex processes into smaller, manageable tasks, operating across all network levels in a coordinated manner A protocol suite comprises these individual protocols working together.
Understanding network protocols requires familiarity with the seven-layer OSI model This model divides network communication into independent layers, allowing for efficient, modular task assignment.
In an OSI model, seven network layers are separated into two groups namely upper layers like 7,
6 & 5 whereas lower layers like 4, 3, 2, & 1 Here, the upper layers mainly deal with the issues of application whereas the lower layers mainly deal with the issues of data transport
Public Switched Telephone Networks (PSTN) utilize circuit-switched telephone systems, employing a single, dedicated connection between two points for standard analog phone calls.
OPERATING PRINCIPLES (P3)
NETWORKING DEVICES
Address: IP verson 4 and IP verson 6
Routers connect devices to the internet, optimizing data transmission and prioritizing network access while providing crucial security for your business.
Home networks, powered by routers, connect numerous internet-enabled devices—computers, smartphones, smart TVs, and more—optimizing internet traffic for speed and efficiency.
Home networks handle diverse data, from emails to streaming video, with varying bandwidth demands Increasing numbers of IoT devices strain routers, demanding greater processing power.
Network switches learn the MAC addresses of connected devices via their NICs This allows the switch to direct incoming and outgoing network packets to the correct device.
The MAC address identifies the physical device and doesn’t change, while the network layer (Layer
3) IP address, can be assigned dynamically to a device and change over time (Think of a MAC address as the VIN number on a car, and the IP address as the license plate.)
Switches examine packet headers, match destination addresses, and forward packets through appropriate ports to reach destination devices.
Most switches utilize full-duplex functionality to prevent network collisions This allows simultaneous data transmission and reception between the switch and connected devices, maximizing bandwidth (unlike half-duplex, which is analogous to a walkie-talkie).
There are two behind-the-scene players that work as partners to get a website to show up on your screen properly: the browser and the web server
When an internet searcher types in a URL, the browser divides the URL into three parts:
The hypertext transfer protocol: http
The server name: www.thewebsite.com
The file name: web-server.htm
Each of these parts have a different responsibility when it comes to interacting with a web server
HTTP is the communication language between web browsers and servers Browsers send HTTP requests to servers, which then return web pages.
Servers verify requested URLs against existing files; a match results in rapid file delivery, while a mismatch triggers an error page response.
The Domain Name System (DNS) translates human-readable domain names into numerical IP addresses Browsers use DNS to find a website's IP address, enabling connection to the server hosting the website's files.
Web servers store all website data, including HTML, images, CSS, videos, JavaScript, and fonts, compiling these elements into the user's viewed website.
Understand how the internet works Learn web basics in under 60 seconds Watch next Wednesday's video for more.
COMMON NETWORKING DEVICES
Network hubs connect multiple devices, transmitting both digital (packets) and analog (signals) information Acting as repeaters, they amplify weakened signals Hubs operate at the OSI model's Physical layer.
Network switches are multiport devices enhancing network efficiency by intelligently forwarding data packets to their correct destinations Unlike hubs, switches use packet information for targeted delivery, though their network-wide knowledge remains limited.
Bridges connect network segments, filtering data packets (frames) to regulate traffic flow and segment larger networks While once common, bridges are largely being replaced by more functional switches.
Gateway devices ensure interoperability between disparate technologies like OSI and TCP/IP, acting as translators between their respective communication protocols Essentially, a gateway functions as a sophisticated router with enhanced translation capabilities.
Modems, short for modulator-demodulators, convert digital signals to analog for transmission over analog lines, then convert them back to digital at the destination.
COMMON TYPES OF SERVERS
A DHCP Server uses the Dynamic Host Communication Protocol (DHCP) to configure the network settings of client computers
DHCP servers automate network configuration for LAN computers, eliminating the need for manual static IP address and network setting assignments on large networks.
Some examples of DHCP options are Router (default gateway), DNS Servers, and DNS Domain Name
A DNS server, or “Domain Name Service” server, is used to translate domain names to their corresponding IP addresses
Domain names, replacing complex IP addresses, allow users easy website access and provide organizations with memorable branding Servers translate these domain names into IP addresses, facilitating seamless browsing.
Internet Service Providers (ISPs) usually supply DNS servers, but free alternatives exist, including Google Public DNS (8.8.8.8).
(for example, www.amazon.com) to machine readable IP addresses (for example, 192.0 2.44) Catalog Server
Catalog servers, such as directory or name servers, maintain an index of information across distributed networks encompassing computers, users, files, and web applications Client programs, including email clients, file searchers, and domain login systems, rely on these servers to locate network resources.
Communication servers maintain the environment enabling communication endpoints to locate and connect These servers may or may not include endpoint directories or presence detection, depending on network security Their function is to facilitate communication between endpoints.
INTER-DEPENDENCE OF WORKSTATION HARDWARE (P4)
Interdependence
Meaning: the fact of depending on each other e.g our interdependence as a global society
The conference discussed the possibility of regional economic interdependence.
Workstation hardware
Workstations (WS) are high-performance computers designed for business and professional use, featuring superior processing power, increased RAM, enhanced graphics capabilities, multiple high-resolution displays, and greater storage capacity than personal computers (PCs), enabling superior multitasking.
Networking software
Network software is an umbrella term used to describe a wide range of software that streamlines the operations, design, monitoring, and implementation of computer networks
Network software is essential for managing and securing network infrastructure It simplifies network complexity, enabling efficient monitoring and control of traffic This software is crucial for administrators and security personnel.
IT operations by facilitating communication, security, content, and data sharing.
Inter-dependence of these …
Workstations are high-performance personal computers offering greater speed and power than standard PCs They function independently, requiring only installed applications and dedicated hard drive space.
A network interface card (NIC) enables computers to connect to a local area network (LAN), facilitating data packet communication via defined protocols Acting as a translator, the NIC allows networked computers to send and receive data, commonly utilized by information systems specialists for wired or wireless network setups.
1 In a structure including Software (web server, OS, driver) and hardware (NIC) If the processing speed of server is 100Mbps and the processing speed of Nic is just 10Mbps, so connection speed is 10Mbps and vice versa As a result, they are inter-dependent, they need each other to work effectively
2 An iPod is used to play recorded music in the form of an MP3 In order to hear to recorded music, you need three effects an iPod, a speaker, and an MP3 train In this analogy, both the iPod and the speaker are exemplifications of tackle The MP3 train, in this case, would represent software Without the iPod or the speaker, you would not be suitable to hear to the MP3 By the same commemorative, the iPod and the speaker would be empty without the MP3 lines to play.
SERVER (M2)
Common server types
Web apps, run on application servers, eliminate the need for local installations, accessible via web-enabled PCs, even offline.
Catalog servers, such as directory or name servers, maintain an index of information across distributed networks including computers, users, files, and web applications Clients, like email clients searching for addresses or users locating files, rely on these servers to navigate the network.
Communication servers maintain the environment enabling endpoints to locate and connect These servers may or may not include directories or presence detection, depending on network security Their clients are the communication endpoints themselves.
Networked computing servers pool CPU and RAM resources, enabling programs demanding high processing power to utilize them via a client-server model requiring networked client computers.
Database servers manage and share any type of database across networks Databases are structured data collections with defined properties, often tabular Numerous applications, including spreadsheets and enterprise software, utilize these servers to access and process organized data.
Justify my selection …
With the scenario given, I choose a Cloud server because of some reasons:
Cloud hosting eliminates capital expenditure on infrastructure and offers pay-as-you-go pricing, unlike traditional hosting which requires upfront infrastructure investment and fixed costs regardless of usage.
Traditional hosting shares server resources among multiple websites, limiting performance and security Dedicated servers offer enhanced security for sensitive data but are expensive.
Cloud hosting offers robust multi-layered security encompassing data, network, application, and physical protection, along with features like encryption, backup recovery, firewalls, identity management, and data isolation.
Cloud hosting offers scalable resources, allowing for instant allocation of storage, bandwidth, and RAM to meet website or application demands Dynamic resource adjustments are easily managed from a server cluster.
A traditional hosting setup has rigid specifications and limited resources You cannot instantaneously ramp up resources if the need arises
Website loading speed depends on server proximity; choose a hosting server geographically close to your target audience to minimize latency.
Cloud hosting servers, on the other hand, are available and accessible via the internet and with any PC or mobile device, from any location around the world
Cloud hosting enables global access to shared documents and applications, boosting employee flexibility and productivity—a key advantage over traditional hosting methods.
The cloud hosting multi-server setup allows for data to be automatically backed up This provides for a fast and easy disaster recovery feature
Traditional single-server hosting lacks inherent disaster recovery capabilities due to its reliance on a single point of failure Robust backup solutions are crucial for disaster recovery in this setup.
1 CPU 2GB 30GB 140.000VND/month
2 CPU 2GB 40GB 210.000VND/month
3 CPU 4GB 60GB 280.000VND/month
4 CPU 6GB 80GB 440.000VND/month
5 CPU 8GB 120GB 660.000VND/month
6 CPU 12GB 160GB 1.320.000VND/month
To match the requirements of the problem, we choose Cloud server 4 CPU, 8 GB RAM, 120 GB SSD storage Using Intel E5 CPU with 100% Enterprise SSD.
IDENTIFY TOPOLOGY PROTOCOL SELECTED (D1)
Topology protocol chosen
There are many options for choosing topology protocol in this network system I choose Star topology to get the most effective result and I choose it for the folowing reasons:
Centralized management helps monitor the network by using the central computer, hub, or switch User-friendly:
In star topology, new nodes can be added easily without affecting the rest of the network
Network component addition and removal are simple, facilitating easy computer integration and quick malfunctioning unit replacement, thus maintaining productivity.
If one cable or device fails, then all the others will still work So, the failure of one node or link doesn’t affect the rest of the network
Star topology minimizes data collisions due to each device's individual connection to a central core, resulting in superior network performance.
Easy fault detection because the link is often easily identified At the same time, it’s easy to detect the failure and troubleshoot it
No point-to-point connections:
Star topology networks offer secure data transmission via unicast and point-based connections, regardless of network size, eliminating signal reflection risks.
Star topology's centralized design ensures high security and reliability; a single cable or NIC failure impacts only one node, requiring central device disabling to affect the entire network This makes it a secure and scalable solution for businesses of all sizes.
Point out selection
I will choose appropriate protocols and provide enough convenience for users:
TCP/IP is the fundamental internet communication protocol, enabling network devices to interconnect It's also crucial for private networks like intranets and extranets.
FTP facilitates webpage file transfer from origin to server, efficiently handling large files and directories Its dual-connection design—one for data, one for control—enables resumed transfers, data recovery, and efficient file management, crucial for networked printers.
SMTP configures server communication, identifying servers and communication types, handling issues like incorrect email addresses (returning error messages), and enabling simple, unrestricted connections to any system.
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