Table of Content
- Podcast Version
- Wired Networks vs Wireless Networks
- Major Networking Hardware Components
- Wireless Network System Components
- Wireless Network Infrastructures and Management System
Podcast Version
Wired Networks vs Wireless Networks
What is Wired Networks?
- Also called Ethernet networks, they are the most common type of local area network (LAN) technology.
- A collection of two or more computers, printers, and other devices linked by Ethernet cables.
- Can be used as part of other wired and wireless networks.
- A computer needs an Ethernet adapter to connect via cable. Some computers have a built-in port.
Basic Network Topology
Star Network
- Has a central hub that connects to three or more computers and printers. Useful for small businesses/home networks. Processing can be centralised and local. Major disadvantage is its vulnerability (if the central hub fails).
Bus Network
Has no central computer; all computers are linked on a single circuit. - Broadcasts signals in all directions. - Uses special software to identify which computer gets what signal. - If one computer fails, others are not affected and can still send messages. - One disadvantage: only one signal can be sent at a time; simultaneous signals collide and fail.
Ring Network
Does not rely on a central host computer. - Each computer communicates directly with any other. - Each processes its own applications independently. - Forms a closed loop, and data is sent in one direction only. - If a computer fails, data is still able to be transmitted.
Wireless Networks
- Use high-frequency radio waves instead of wires to communicate between nodes.
- An option for home or business networking.
- Can expand existing wired networks or go completely wireless.
- Allows device sharing without cables, increasing mobility but decreasing range.
- Two main types: peer to peer (ad-hoc) and infrastructure.
Wired Networks vs Wireless Networks
- Wired uses network cables, wireless uses radio frequencies.
- Wired allows for a faster and more secure connection. Limited to distances shorter than 2,000 feet. Cost is rather inexpensive. Offer superior performance. For wired networks connected to the Internet, firewalls are the primary security consideration.
- Wireless is less secure. Transmission speeds can suffer from outside interference. Wireless gear costs somewhat more than wired equivalents. Performance is distance sensitive, degrading farther from the access point. Performance degrades further as more devices utilise the network (802.11 LAN). The greater mobility of wireless helps offset the performance disadvantage. Wireless communication signals travel through the air and can easily be intercepted. Weaknesses are considered more theoretical than practical. Data is protected through Wired Equivalent Privacy (WEP) encryption, making communications reasonably as safe as wired ones.
| Feature | Wired Network | Wireless Network |
|---|---|---|
| Transmission | Network cables | Radio frequencies |
| Speed | Faster, superior performance | Slower, susceptible to interference |
| Security | More secure (firewalls primary concern) | Less secure (though WEP encryption helps) |
| Range | Limited (shorter than 2000 feet) | Distance-sensitive; degrades with distance |
| Cost | Less expensive | More expensive |
| Mobility | Limited | High |
| Interference | Less susceptible | Susceptible to outside interference |
| Scalability | Easier to scale with added cables/switches | Performance degrades with more devices (802.11 LAN) |
Benefits of a Wi-Fi Wireless Network (for Businesses)
- Convenience.
- Mobility.
- Productivity.
- Expandability.
- Security.
- Reduced cost.
Major Networking Hardware Components
These are major parts needed to install network software. Some can be removed depending on the network type (e.g., wireless doesn’t need cables).
Components listed:
- NIC
- Switch
- Cables and connectors
- Hub
- Router
- Modem
NIC (Network Interface Card):
- A hardware component to connect a computer with another computer onto a network.
- Can support transfer rates of 10, 100 to 1000 Mb/s.
- The MAC address (physical address) is encoded on the chip and assigned by the IEEE to uniquely identify the card. Stored in PROM (Programmable read-only memory).
- Exists as Wired NIC and Wireless NIC.
- Provides the interface between the computer device and the wireless network infrastructure.
- Fits inside the device, but external adaptors are available.
- Wireless network standards define how a wireless NIC operates.
- Comply with specific form factors defining physical/electrical bus interface (ISA, PCI, PC Card, Mini-PCI, CompactFlash).
Hub:
- Traditional hardware device that divides the network connection among multiple devices.
- When a computer requests information, it sends the request to the Hub.
- The Hub broadcasts this request to the entire network.
- This process consumes more bandwidth and limits communication.
- Has been replaced by more advanced components like Switches and Routers.
Switch:
- Hardware device that connects multiple devices on a computer network.
- Contains more advanced features than a Hub.
- Contains an updated table deciding where data is transmitted.
- Delivers the message to the correct destination based on the physical address.
- Does not broadcast the message to the entire network like the Hub.
- Determines the specific device the message is for.
- Provides a direct connection between source and destination.
- Increases the speed of the network.
- Operates at Layer 2 (Data link layer) in the OSI Reference Model.
Router:
- Hardware device used to connect a LAN with an internet connection.
- Used to receive, analyse, and forward incoming packets to another network.
- Works in Layer 3 (Network layer) of the OSI Reference Model.
- Forwards packets based on information in the routing table.
- Determines the best path for packet transmission.
- Advantages:
- Security: Only the specified addressed device can read the data traversing the cable.
- Reliability: If one server/network goes down, others served by the router are unaffected.
- Performance: Enhances overall performance by potentially splitting a single network into multiple segments to reduce traffic load.
- Network range.
Modem:
- Hardware device allowing the computer to connect to the internet over existing telephone lines.
- Installed on the PCI slot on the motherboard (not integrated).
- Stands for Modulator/Demodulator.
- Converts digital data into an analog signal over telephone lines.
- Categories mentioned based on speed/transmission rate: Standard PC modem (Dial-up), Cellular Modem, Cable modem.
Cables and Connectors:
- Transmission media used for transmitting signals.
- Three types used:
- Twisted pair cable: Classified as Category 1-7. Cat 5E, 6, 7 are high-speed (1Gbps+).
- Coaxial cable: Example is TV installation cable.
- Fibre-optic cable: High data transmission cable.
Wireless Network System Components
Wireless networks include computer devices, base stations, and a wireless infrastructure.
Components listed:
- Users
- Computer Devices
- NICs
- Air Medium
Users:
- Anything that directly utilises the wireless network.
- Most common type is a person.
- The network exists to serve the user, who receives the benefits.
- The user initiates and terminates use, making “end-user” appropriate.
- Typically operates a computer device providing an interface to the network.
- Often mobile, constantly moving. Mobility is a prominent benefit.
- Some users might require only portability, while others are stationary.
Computer Devices:
- Sometimes referred to as clients, they operate on a wireless network.
- Can be designed specifically for users or be end systems.
- Any device might communicate with any other on the same network.
- Often small for mobile applications. Larger for portable and stationary applications.
- Include end systems such as servers, databases, and websites.
- Many existing devices can be adapted for wireless networks.
- Requires an operating system (Windows XP, LINUX, MAC OS) to run software for the network application.
NICs:
- As covered previously, provides the interface between the computer device and the wireless network infrastructure. (Details repeated from earlier section).
Air Medium:
- Provides a medium for the propagation of wireless communications signals, which is the heart of wireless networking.
- The conduit by which information flows between devices and infrastructure.
- Information signals travel through the air with special properties for long-distance propagation.
- Elements like rain, snow, smog, and smoke can impair propagation.
- Supports the propagation of radio and light waves.
Wireless Network Infrastructures and Management System
Wireless Network Infrastructures:
- Base Stations
- Access Controllers
- Application Connectivity Software
- Distribution System
Base Station:
- A common infrastructure component that interfaces wireless communications signals traveling through the air to a wired network.
- Enables users to access a wide range of network services.
- Go by different names depending on purpose: Access point, Gateways, Routers.
Access Controllers:
- Offered by companies to strengthen wireless systems, especially regarding security, quality of service (QoS), and roaming.
- Reduce the need for expensive smart access points.
- Generally employ features like Authentication, Encryption, Subnet Roaming, and Bandwidth Management.
- Benefits include Lower Costs, Open Connectivity, and Centralized support.
Application Connectivity Software:
- Applications like web surfing and e-mail perform well. Protocols for these are resilient if a connection is lost.
- Various types include: Terminal Emulation, Direct Database Connectivity, Wireless Middleware.
- Wireless Middleware efficiently interconnects computer device applications to Hosts and Servers. Features include Optimization techniques, Intelligent restarts, Data bundling, Screen scraping and reshaping, End system support.
Distribution System:
- A wireless network is seldom entirely free of wires; the distribution system, often including wiring, ties together access points, access controllers, and servers.
- Commonly comprises Ethernet.
- Based on the IEEE 802.3 standard and the CSMA protocol for shared medium access (twisted-pair, coaxial, optical fiber).
Network Architecture (OSI Reference Model):
Represents all functions of a network in layers.
- Layer 1—Physical layer: Provides the actual transmission of information through the medium (e.g., radio waves, infrared light).
- Layer 2—Data link layer: Ensures medium access, synchronization, and error control. With wireless, this involves coordinating access to the air medium and recovering from data errors.
- Layer 3—Network layer: Provides the routing of packets from source to destination (e.g., Internet Protocol (IP) operates here).
- Layer 4—Transport layer: Provides mechanisms for establishing, maintaining, and terminating virtual circuits, shielding higher layers from implementation details. These are connections between applications (e.g., Transmission Control Protocol (TCP) operates here).
- Layer 5—Session layer: Establishes, manages, and terminates sessions between applications. Handled by wireless middleware and access controllers. Suspend communications during interference.
- Layer 6—Presentation layer: Negotiates data transfer syntax and performs translations between different data formats.
- Layer 7—Application layer: Establishes communications among users and provides basic services (file transfer, email). Examples: Simple Mail Transfer Protocol (SMTP), HyperText Transfer Protocol (HTTP), File Transfer Protocol (FTP)
Wireless Network Management System:
Elements include:
- Security: Mechanisms to avoid compromise/damage of network resources. Enforcing policies (like encryption) to counter issues from signal propagation.
- Help Desk: First level of user support. Solves simple problems (e.g., configuring radio card/OS). Interfaces with advanced support.
- Configuration Management: Controls changes made to the architecture and system. Requires reviewing modification proposals and an independent design review process.
- Network Monitoring: Continuously measures network attributes (access point utilization, user traffic routes). Measures base station usage for scaling. Tools alert on outages.
- Reporting: Provides information (usage statistics, security alarms, performance). Necessary for managers to gauge operation and make decisions. Should be available to operational support functions.
- Engineering: Advanced technical support for reengineering with newer technologies and solving problems. Reviews designs for compliance. Monitors technology evolution for migration.
- Maintenance: Repairs and configures the network. Includes replacing antennae, setting channels, re-evaluating propagation. Important tasks include upgrading access point firmware and performing periodic coverage tests.