Network 101

Introduction to Networking:

A computer network refers to a collection of interconnected devices, such as computers, servers, routers, switches, and other networking equipment. These devices are linked together to facilitate communication, data sharing, and resource sharing between users or systems. Computer networks can be categorized based on their geographical scope and the types of connections they utilize.

Networking offers several advantages, including:

• Resource Sharing: Networks allow users to share hardware devices (such as printers or scanners) and software applications, enabling cost savings and improved efficiency.

• Data Sharing: Networks enable the sharing and transfer of data between connected devices, fostering collaboration and enhancing productivity.

• Communication: Networks facilitate real-time communication through methods like email, instant messaging, and video conferencing, enabling effective collaboration and remote work.

• Centralized Management: Networks allow for centralized management of resources, user accounts, and security settings, making it easier to control and maintain the network infrastructure.

• Scalability: Networks can be scaled to accommodate additional devices and users as an organization grows, providing flexibility and adaptability.

Types of Networks

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There are three primary types of computer networks:

1. Local Area Network (LAN): A LAN is a network that spans a small geographic area, such as a home, office building, or campus. LANs are typically privately owned and offer high-speed data transfer rates. They are commonly used to connect devices within a single location.

2. Wide Area Network (WAN): A WAN covers a large geographical area and typically spans multiple locations, such as cities, countries, or continents. WANs utilize public or private telecommunication networks to connect geographically dispersed devices. The Internet is the most prominent example of a WAN.

3. Metropolitan Area Network (MAN): A MAN falls between a LAN and a WAN in terms of size and geographical coverage. It typically covers a larger area than a LAN but is smaller than a WAN. MANs are often used to connect multiple LANs within a city or metropolitan area.

Common Network Topologies:

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Network topology refers to the physical or logical layout of devices and connections within a network. Here are three common network topologies:

1. Bus Topology: In a bus topology, all devices are connected to a single communication line, called a bus. Data is transmitted along the bus, and each device receives the transmitted data. However, if the bus fails, the entire network may be affected.

2. Star Topology: In a star topology, each device is connected directly to a central hub or switch. All data transmission occurs through the hub, which enables better performance and fault isolation. If one device fails, the rest of the network remains unaffected.

3. Ring Topology: In a ring topology, devices are connected in a circular manner, forming a closed loop. Each device receives data from its preceding device and passes it along to the next device. Ring topologies provide equal access to all devices but can be susceptible to failures if one device or connection breaks.

Network Devices and Components

Overview of Network Devices: Network devices are physical or virtual components that are used to facilitate communication, data transfer, and resource sharing within a computer network. These devices play crucial roles in the operation and management of networks.

OSI (Open Systems Interconnection) model:

Layer 1 - Physical Layer: Devices at Layer 1 are responsible for the physical transmission of data over the network medium. They include:

• Network cables

• Network Interface Cards (NICs)

Layer 2 - Data Link Layer: Devices at Layer 2 focus on the reliable transfer of data frames between directly connected network nodes. The Data Link Layer handles tasks such as framing, error detection and correction, and access control.They include:

• Switches

• Wireless Access Points (APs)

Layer 3 - Network Layer: Devices at Layer 3 are responsible for routing and forwarding data packets across multiple networks. The Network Layer handles logical addressing, routing, and path determination to enable communication between different IP subnets or networks. They include:

• Routers

• Layer 3 Switches

Routers, Gateways, Switches

Routers and gateways are devices that enable communication between different networks. They analyze network addresses and determine the most efficient paths for data transmission:

• Switches: Switches are intelligent devices that operate at the data link layer (Layer 2) of the network. They examine the destination MAC (Media Access Control) addresses of incoming data packets and forward them to the appropriate device within the network. Switches provide dedicated bandwidth to each connected device, enabling simultaneous data transmission and enhancing network performance.

• Routers: Routers operate at the network layer (Layer 3) and connect multiple networks together, such as LANs, WANs, or the Internet. They use routing tables and protocols to determine the optimal path for data packets to reach their destination. Routers can perform functions like IP address assignment, network traffic management, and network security.

• Gateways: Gateways serve as interfaces between networks with different protocols or architectures. They translate data and protocols between networks, allowing communication between otherwise incompatible systems. Gateways are commonly used to connect local networks to the Internet or to connect networks using different communication standards.

Firewalls and Security Appliances

Firewalls and security appliances are devices designed to protect networks from unauthorized access, malicious activities, and security threats:

• Firewalls: Firewalls are network security devices that enforce security policies and control traffic flow between networks. They monitor incoming and outgoing network traffic, examine data packets, and make decisions based on predetermined rules. Firewalls can block suspicious traffic, filter content, and provide network security through features like intrusion detection and prevention.

• Security Appliances: Security appliances encompass a broader category of devices that focus on network security. These devices may include intrusion detection and prevention systems (IDS/IPS), virtual private network (VPN) gateways, antivirus gateways, and other security-related hardware or software solutions.

Network Cables and Connectors

Network cables and connectors are physical media used to establish wired connections between network devices:

CAT (Category) Cables

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CAT cables are twisted pair copper cables widely used in Ethernet networks. Key points about CAT cables include:

• Cabling Categories: CAT cables are categorized based on their performance and capabilities, such as CAT5, CAT6, CAT6a, and CAT7.

• Data Transmission: CAT cables use twisted pairs of copper wires to transmit data signals. They can support different Ethernet standards, offering varying speeds and bandwidths.

• Common Applications: CAT cables are commonly used in office and home networks, connecting devices like computers, routers, switches, and IP phones.

• Distance Limitations: CAT cables have distance limitations, with longer distances potentially leading to signal degradation and slower transmission speeds.

Fiber Optics

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Fiber optics use thin strands of glass or plastic fibers to transmit data as pulses of light. Key points about fiber optics include:

• Light-based Transmission: Fiber optic cables transmit data using light signals, providing high-speed and long-distance communication.

• Bandwidth and Speed: Fiber optics offer high bandwidth and data transfer rates, capable of supporting large amounts of data over long distances.

• Immunity to Interference: Fiber optics are immune to electromagnetic interference, making them ideal for environments with electrical noise or interference.

• Common Applications: Fiber optics are commonly used in high-speed internet connections, long-distance telecommunications, data centers, and backbone networks.

COAX (Coaxial) Cables

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COAX cables consist of a central conductor surrounded by insulation and a metal shield. Key points about COAX cables include:

• Shielded Transmission: COAX cables use the metal shield to protect the central conductor from interference and signal loss.

• Broadband Capabilities: COAX cables offer excellent signal quality and can support high-frequency transmissions, making them suitable for cable TV, broadband internet, and cable modem connections.

• Distance Limitations: COAX cables have distance limitations, and signal quality can degrade over longer distances.

• Flexible Installation: COAX cables are relatively flexible and can be used in various setups, including residential, commercial, and broadcast applications.

Network Adapters and Interface Cards:

Network adapters, also known as network interface controllers (NICs), are devices that enable computers and other devices to connect to a network:

• Network Adapters: Network adapters are hardware components or integrated circuits that provide the interface between a device and a network. They are typically integrated into computers or can be added externally. Network adapters convert digital data into signals that can be transmitted over network cables or wireless connections.

• Interface Cards: Interface cards, also referred to as expansion cards or network interface cards (NICs), are hardware components that can be added to computers or devices to provide network connectivity. These cards are inserted into expansion slots on a computer's motherboard and offer various types of network interfaces, such as Ethernet or wireless.

Networking Protocols and Standards

Networking protocols are a set of rules and standards that govern communication between devices in a network. They define how data is transmitted, received, and interpreted, ensuring effective device communication.

Examples of networking protocols:

• TCP/IP (Transmission Control Protocol/Internet Protocol)

• UDP (User Datagram Protocol).

• HTTP (Hypertext Transfer Protocol)

• HTTPS (Hypertext Transfer Protocol Secure)

TCP/IP Protocol Suite

The TCP/IP protocol suite forms the foundation of the modern internet. It is a comprehensive set of protocols that enables communication and data transfer across networks. TCP/IP provides the necessary mechanisms for addressing, routing, and reliable data transmission, allowing devices to connect and exchange information seamlessly on a global scale.

• UDP (User Datagram Protocol): UDP is a connectionless transport protocol that offers a lightweight and fast method of data transmission. In the context of CCTV systems, UDP can be beneficial for live video streaming and real-time surveillance. It operates on a "best-effort" basis, meaning it does not guarantee reliable delivery or packet order. UDP is suitable for situations where real-time video is prioritized over data integrity. In CCTV systems, UDP can be utilized for live video feeds where occasional packet loss or minor delays are acceptable.

• TCP (Transmission Control Protocol): TCP is a connection-oriented transport protocol that provides reliable and ordered data transmission. It establishes a connection between the sender and receiver, ensuring that data is delivered without loss or corruption. TCP is suitable for CCTV systems when data integrity and complete delivery are crucial, such as when transmitting recorded video footage or critical system information. While TCP introduces slightly higher latency due to its acknowledgment and retransmission mechanisms, it guarantees reliable data transfer and ensures that all packets are received in the correct order.

Ethernet in CCTV Systems

Ethernet, a widely adopted wired networking technology, plays a crucial role in CCTV systems for reliable and efficient data transmission. It utilizes various cabling types and standards, such as Cat5e and Cat6, to establish robust connections between CCTV cameras, recording devices, and network infrastructure. Ethernet provides the following benefits for CCTV systems:

• Reliable and stable connection: Ethernet ensures reliable data transmission, minimizing potential interference and signal loss. This reliability is particularly essential in CCTV systems, where consistent video streaming and data integrity are paramount.

• Bandwidth capabilities: Ethernet offers high bandwidth capabilities, allowing for the transfer of large amounts of video data from CCTV cameras to recording devices or network video recorders (NVRs). This is crucial for capturing high-quality video footage in CCTV systems.

• Security and control: Ethernet-based CCTV systems can have dedicated and secure network infrastructure, providing enhanced control over access to surveillance video and facilitating centralized management of cameras and recording devices.

Wi-Fi in CCTV Systems

While not widely used in CCTV systems Wi-Fi can be utilized to connect hard to reach areas for cameras. The most common application is to use a wireless device as a break in the network cable to “jump” from one area to another. This is more secure than a wireless network, where you would have to consider firewall rules.

Other Protocols:

DNS (Domain Name System):

• Translates domain names to IP addresses.

• Allows locating resources on the internet.

DHCP (Dynamic Host Configuration Protocol):

• Automates IP address assignment and network configuration.

• Simplifies network administration.

SNMP (Simple Network Management Protocol):

• Facilitates network management and monitoring.

ARP (Address Resolution Protocol):

• Resolves IP addresses to MAC addresses.

Overview of IP Addressing

IP addressing is a fundamental aspect of computer networks that allows devices to communicate with each other over the internet or local networks. This knowledge base (KB) article provides an overview of IP addressing, including IPv4 and IPv6 addresses, private and public IP addresses, as well as subnetting and subnet masks.

IP Addressing

An IP (Internet Protocol) address is a unique numerical identifier assigned to each device connected to a network. It enables devices to send and receive data packets across the internet or a local network. IP addressing provides a standardized way to identify and locate devices on a network.

• IPv4 addresses:

  • Consist of 32 bits and are expressed in a dotted-decimal format (e.g., 192.168.0.1).

  • IPv4 addresses were the primary addressing system for many years and are still widely used.

  • However, the limited number of available IPv4 addresses has led to the development and adoption of IPv6.

Private and Public IP Addresses

IP addresses can be classified as private or public, depending on their usage within a network.

• Private IP addresses:

  • Reserved for use within private networks, such as home or office networks.

  • Private IP addresses are not routable on the public internet and are used for internal communication within a network.

  • Examples of private IP address ranges include:

    • IPv4: 10.0.0.0 to 10.255.255.255, 172.16.0.0 to 172.31.255.255, 192.168.0.0 to 192.168.255.255

• Public IP addresses:

  • Globally unique addresses assigned to devices connected to the public internet.

  • Public IP addresses enable direct communication with other devices on the internet.

  • These addresses are used for hosting services, websites, and facilitating direct inbound communication.

Subnetting and Subnet Masks

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Subnetting is the process of dividing a larger IP network into smaller subnetworks or subnets.

• Subnetting:

  • Enhances network efficiency and management by organizing devices into logical groups.

  • Subnetting allows for more efficient utilization of IP addresses, especially in large networks.

• Subnet Masks:

  • Used in conjunction with IP addresses to determine the network and host portions of an address

  • They define the boundaries of the network and enable proper routing of data packets.

Static and Dynamic IP Addressing

In computer networks, IP addressing plays a vital role in identifying and communicating with devices.

Static IP Addressing

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Static IP addressing involves manually assigning a fixed IP address to a device instead of obtaining one dynamically from a DHCP server. Key points about static IP addressing include:

• Manual configuration: A network administrator configures the IP address, subnet mask, default gateway, and DNS server settings on the device.

• Consistency: The assigned IP address remains the same unless manually changed, ensuring consistent connectivity and easy identification of the device on the network.

• Specific network requirements: Static IP addressing is typically used for devices that require permanent IP addresses, such as servers, routers, or devices hosting specific services or applications.

Dynamic IP Addressing

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Dynamic IP addressing allows devices to obtain IP addresses automatically from a DHCP server. Key points about dynamic IP addressing include:

• Automatic assignment: Devices using dynamic IP addressing request an IP address from a DHCP server, which assigns an available IP address from a predefined pool.

• Flexibility and scalability: Dynamic IP addressing simplifies network administration by dynamically managing IP address allocation and ensuring efficient utilization of IP resources.

• Lease duration: The DHCP server assigns IP addresses for a specific lease duration. When the lease expires, the device can request a renewal or obtain a new IP address.

• Centralized management: Dynamic IP addressing allows network administrators to centrally manage IP address assignment, including subnet masks, default gateways, and DNS server settings.

Networking Tools:

Crimper

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A crimper is a tool used to attach connectors to the ends of network cables. Key points about the crimper include:

• Connector Attachment: The crimper applies pressure to crimp connectors onto the wires of a network cable, ensuring a secure and reliable connection.

• Connector Types: Crimpers are designed to work with specific connectors, such as RJ-45 connectors for Ethernet cables.

Cable Stripper

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A cable stripper is a tool used to remove the outer insulation or jacket from network cables. Key points about the cable stripper include:

• Insulation Removal: The cable stripper cuts and removes the outer jacket of a network cable, exposing the inner wires for termination or connector attachment.

• Precision and Control: Cable strippers are designed to remove the insulation without damaging the inner wires, ensuring proper signal transmission.

Toner Probe

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A toner probe is a tool used to trace and identify network cables in a complex network infrastructure. Key points about the toner probe include:

• Cable Tracing: The toner probe emits a tone that can be detected by a corresponding probe, allowing network technicians to locate specific cables in a bundle or wiring closet.

• Cable Identification: Toner probes help identify cables when no labeling is available or when cables are not visually distinguishable.

Punchdown Tool

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A punchdown tool is used for terminating network cables onto punchdown blocks, patch panels, or keystone jacks. Key points about the punchdown tool include:

• Termination Process: The punchdown tool inserts the individual wires into the appropriate slots, creating a secure connection between the cable and the termination point.

• Consistent Terminations: The punchdown tool ensures proper wire seating and reduces the risk of signal loss or cross-talk.

Cable Tester

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A cable tester is a tool used to verify the continuity and integrity of network cables. Key points about the cable tester include:

• Cable Verification: Cable testers can check for continuity, wiring faults, and cable length, ensuring that network cables are properly wired and functional.

• Cable Types: Cable testers support various network cable types, such as Ethernet (CAT5e, CAT6), coaxial, or fiber optic cables.

Loopback Plug

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A loopback plug is a device used to test network interfaces or connections by looping the transmitted signal back to the source. Key points about the loopback plug include:

• Signal Testing: Loopback plugs simulate network connections by sending signals from a device and looping them back to the same device for verification.

• Troubleshooting: Loopback plugs help diagnose issues related to network interfaces, identify faulty components, or test the functionality of network devices.

Network Tap

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A network tap is a device used to capture and monitor network traffic for analysis or security purposes. Key points about the network tap include:

• Traffic Capture: Network taps passively capture network traffic by diverting a copy of the traffic to monitoring devices or tools.

• Non-Intrusive Monitoring: Network taps do not interfere with the network flow, ensuring accurate and reliable packet capture.

• Network Analysis and Security: Network taps facilitate network analysis, performance monitoring, and security monitoring, allowing for in-depth analysis of network traffic.

Common troubleshooting steps:

1. Check physical connections:

   • Ensure all network cables are securely plugged in.

   • Verify that the network devices (routers, switches, etc.) have power and are functioning properly.

2. Restart network devices:

   • Power cycle the modem, router, and other network devices by turning them off, waiting for a few seconds, and then turning them back on.

3. Verify IP settings:

   • Use the command line tool ipconfig (Windows) or ifconfig (Linux/macOS) to check the IP configuration of the device.

   • Make sure the IP address, subnet mask, gateway, and DNS settings are correct.

4. Ping test:

   • Use the ping command to check connectivity to another device or a specific IP address.

   • For example: ping google.com or ping 192.168.1.1.

   • This helps identify if there is a problem with network connectivity or specific devices.

5. Flush DNS cache:

   • Use the command ipconfig /flushdns (Windows)

   • This can resolve DNS-related issues where domain names are not resolving correctly.

6. Check firewall settings:

   • Verify that the firewall settings on the device or router are not blocking necessary network traffic.

   • Temporarily disable the firewall to test if it's causing any connectivity problems.

7. Trace route:

   • Use the tracert command (Windows) or traceroute command (Linux/macOS) to trace the path packets take to reach a destination.

   • This helps identify any network hops or routers causing delays or connectivity issues.

8. Update network drivers:

   • Ensure that network drivers on the device are up to date. Outdated or incompatible drivers can cause network problems.

   • Visit the manufacturer's website to download and install the latest drivers for the network adapter.

9. Consult network documentation or contact network administrator:

   • Refer to the network documentation or contact the network administrator for further troubleshooting steps specific to your network setup.

Common IP Configuration scenarios:

At times, it may be necessary to change the IP address of a laptop running Windows 10 or Windows 11.

Changing the IP Address

Windows 10

To change the IP address on a laptop running Windows 10, follow these steps:

1. Open the "Settings" app by clicking on the Start button and selecting the "Settings" icon (shaped like a gear).

2. In the Settings window, click on "Network & Internet."

3. Select "Ethernet" or "Wi-Fi" (depending on the type of connection you want to modify).

4. Under the selected connection, click on "Change adapter options."

5. Right-click on the network adapter you wish to change the IP address for and select "Properties."

6. In the Properties window, scroll down and double-click on "Internet Protocol Version 4 (TCP/IPv4)."

7. Choose "Use the following IP address" and enter the desired IP address, subnet mask, default gateway, and DNS server addresses.

8. Click "OK" to save the changes.

Windows 11

To change the IP address on a laptop running Windows 11, follow these steps:

1. Open the "Settings" app by clicking on the Start button and selecting the "Settings" icon (shaped like a gear).

2. In the Settings window, click on "Network & internet."

3. Select "Advanced network settings."

4. Under "Advanced network settings," click on "Change adapter options."

5. Right-click on the network adapter you want to modify and select "Properties."

6. In the Properties window, scroll down and double-click on "Internet Protocol Version 4 (TCP/IPv4)."

7. Choose "Use the following IP address" and enter the desired IP address, subnet mask, default gateway, and DNS server addresses.

8. Click "OK" to save the changes.

Reverting Back to the Original IP Address

To revert back to the original IP address settings on both Windows 10 and Windows 11, follow the same steps outlined above but select "Obtain an IP address automatically" or "Obtain DNS server address automatically" instead of entering specific values for IP configuration. This will allow the laptop to obtain the IP address settings automatically from the network.

Obtaining MAC Address

To obtain the MAC address of a laptop running Windows, follow these steps:

1. Press the Windows key + R to open the Run dialog box.

2. Type "cmd" and press Enter to open the command prompt.

3. In the command prompt window, type "ipconfig /all" and press Enter.

4. Look for the "Physical Address," "Ethernet Address," or "Link-local IPv6 Address" entry under the network adapter for which you want to obtain the MAC address. This entry represents the device's MAC address.