Network Types and Topologies

Network Types and Topologies

• Nodes/Hosts: Devices communicating on a network.
• Network Interface: Translates digital data into signals for transmission, and vice-versa.
• Peer-to-Peer (P2P) Network: Hosts share resources without a central server. Easy to implement but management becomes difficult with many nodes and lacks centralized security.
• Client-Server Network: Hosts have specific roles; servers provide resources, clients consume. More scalable and reliable for data protection with centralized management. More complex to set up, and could be less flexible.
• LAN (Local Area Network): Network within a building or organization.
• MAN (Metropolitan Area Network): Network connecting devices over a city.
• WAN (Wide Area Network): Network connecting networks over a wide geographic area.
• Network: Interconnected devices under one organization's control.
• Internetwork: Multiple networks connected, not controlled by a single entity.
• Internet: Collection of interconnected networks controlled by various entities.
• Intranet: A private network similar to the internet.
• Extranet: A network partly accessible to entities outside an organization.

Network Physical and Logical Topologies

• Physical Topology: Layout of network devices' connections in space.

• Logical Topology: How devices communicate irrespective of physical setup. Examples include:

  • Bus Topology: One single link connects all devices.
  • Ring Topology: Each device connects to two other devices in a ring or closed loop.
  • Mesh Topology: Every device connects to every other device in a network.
  • Star Topology: All devices connect to a central device, often a hub. A common architecture for Ethernet LANs.
  • Partial Mesh: Some nodes are interconnected while others are connected to only a few others.

• Logical Link Control (LLC) Sublayer: Layer 2 in the OSI model, interfaces lower and upper layers.

Data Units (Protocol Data Units) & Layers

• PDU (Protocol Data Unit): An important concept in data communication, specifically related to layers in the OSI model. In each layer, the data is packaged in a different format. Examples:
  • Physical Layer: Bits
  • Data Link Layer: Frames
  • Network Layer: Packets
  • Transport Layer: Segments
    • UDP PDU is Datagram
    • TCP PDU is segments

Network Devices & Services

• WLAN (Wireless Local Area Network): Uses radio waves for communication.
• SAN (Storage Area Network): Provides fast block-level storage access to multiple servers.
• NAS (Network Attached Storage): Provides file-level storage for shared use on a network.
• SD-WAN (Software-Defined WAN): Software manages a WAN network architecture.
• MPLS (Multiprotocol Label Switching): Assigns identifiers for efficient data routing.
• ARP (Address Resolution Protocol): Maps IP addresses to MAC addresses.
• TCP Handshake (3-Way Handshake): Establishes a TCP connection in a three-step process.
  • Open Scan: Full handshake, checks if ports are open.
  • Stealth Scan: Sends a SYN packet, only verifies if the port is open, if the port is closed it will not respond to create security issues.
  • Xmas Tree Scan: Uses multiple flags, less stealthy, harder to hide
  • Idle Scan: Uses a zombie machine to execute the scan (more technical)
• ICMP (Internet Control Message Protocol): Used for network testing and diagnostics (e.g., ping).
• IGMP (Internet Group Management Protocol): Manages communication between computers in a multicast group.

Cabling Types

• Solid wire: Good signal conduction but prone to breakage; used in permanent or semi-permanent installations.
• Stranded Wire: Flexible but with poorer signal transmission; used in cabling that will be moved frequently.
• UTP (Unshielded Twisted Pair) Cabling: Commonly used for Ethernet networks and telephones; cost-effective and easy to implement.