Objective 1.6 Flashcards
1.6 Compare and contrast network topologies, architectures, and types. (19 cards)
Topology: Star
Definition / Key Fact:
Definition: All devices connect to a central point, such as a switch.
Key Fact: This is the most common topology used in modern LANs. A failure of a single end device or cable does not bring down the entire network, making it reliable and easy to troubleshoot.
Topology: Mesh
Definition / Advantage & Disadvantage:
Definition: A topology where devices are interconnected with many redundant paths.
- Full Mesh: Every device connects to every other device.
- Partial Mesh: Critical devices are fully connected, while others have fewer connections.
Advantage: Extremely high availability and reliability.
Disadvantage: Very expensive and complex to implement, especially in a full mesh.
Topology: Hub-and-Spoke
Definition / Use Case:
Definition: A central “hub” (like a main office) has connections radiating out to multiple “spoke” sites (like branch offices).
Use Case: A classic WAN topology for connecting branch locations to a central headquarters. It is simpler and cheaper than a mesh, but the hub is a single point of failure.
Topology: Bus
Definition / Key Fact:
Definition: A legacy topology that uses a single cable (the “bus”) to which all devices connect. Requires terminators at each end.
Key Fact: A break anywhere on the cable would take down the entire network. This topology is obsolete.
Topology: Ring
Definition / Key Fact:
Definition: A legacy topology where devices are connected in a circle. Data is passed from device to device in one direction, often using a “token.”
Key Fact: The failure of a single device or cable would break the loop and take down the network. This topology is obsolete.
Architecture: Client-Server vs. Peer-to-Peer (P2P)
Key Differentiator:
- Client-Server: Centralized model. Clients request resources (web pages, files) from a dedicated, powerful server. This is the standard for most business applications.
- Peer-to-Peer (P2P): Decentralized model. All devices are equal (“peers”) and can both provide and request resources from each other.
Architecture: 3-Tier Architecture
What are the three tiers?
A highly scalable application architecture composed of:
- Presentation Tier (Web Tier): The user interface (e.g., your web browser).
- Application Tier (Logic Tier): The “brains” of the application that processes user input.
- Data Tier (Database Tier): The servers that store and retrieve the data.
Architecture: SDN (Software-Defined Networking)
Core Concept:
It separates the control plane from the data plane.
- Control Plane (The Brain): A centralized software controller that makes all the intelligent decisions about where to send traffic.
- Data Plane (The Muscle): The network hardware (switches, routers) that simply executes the forwarding instructions given by the controller.
Architecture: SD-WAN (Software-Defined WAN)
Key Business Benefits:
An application of SDN to WAN connections. Key benefits include:
- Central Policy Management: Configure all sites from one dashboard.
- Transport Agnostic: Can use any mix of connection types (MPLS, Internet, 5G).
- Application Awareness: Can prioritize critical application traffic (e.g., VoIP over YouTube).
- Zero-Touch Provisioning: Ship an appliance to a site, plug it in, and it automatically downloads its configuration.
Architecture: Zero Trust Architecture (ZTA)
Core Principle / Analogy:
Principle: “Never trust, always verify.” It assumes all users and devices are untrusted, regardless of their physical location, and requires strict verification for every access request.
Analogy: A high-security building where you must show your ID at every single door, not just the front entrance.
Architecture: VXLAN (Virtual Extensible Local Area Network)
Purpose / How it Works:
Purpose: Overcomes the 4,094 VLAN limitation in large data centers.
How: It works by encapsulating a Layer 2 Ethernet frame inside a Layer 3 UDP packet, allowing you to “stretch” a Layer 2 network across different Layer 3 networks.
Architecture: SASE (Secure Access Service Edge)
Core Concept:
SASE (pronounced “sassy”) converges networking services (like SD-WAN) and security services (like firewalls) into a single, cloud-delivered platform. It brings the security controls to the user, wherever they are.
Architecture: Infrastructure as Code (IaC)
Core Concept / Key Tool:
Concept: Managing and provisioning network infrastructure through machine-readable code (e.g., text files) rather than manual configuration. This enables automation, consistency, and prevents “configuration drift.”
Key Tool: A playbook or template—a reusable file that defines the desired state of the network devices.
Network Type: PAN (Personal Area Network)
Scope / Example:
Scope: A few meters, centered around a single person.
Example: Connecting your smartphone to your wireless earbuds or smartwatch via Bluetooth.
Network Type: LAN (Local Area Network)
Scope / Example:
Scope: A single room, an office floor, or a single building.
Example: The network connecting all the computers, printers, and switches in your office.
Network Type: CAN (Campus Area Network)
Scope / Example:
Scope: A collection of interconnected LANs across multiple nearby buildings.
Example: A university network connecting the library, dorms, and administrative buildings.
Network Type: MAN (Metropolitan Area Network)
Scope / Example:
Scope: Spans a city or a large town.
Example: A service provider connecting multiple businesses across a city, or a city-wide public Wi-Fi network.
Network Type: WAN (Wide Area Network)
Scope / Example:
Scope: A large geographical area, such as a state, country, or the entire globe.
Example: The Internet, or a global company connecting its offices in New York, London, and Tokyo.
Network Type: SAN (Storage Area Network)
Scope / Differentiator:
Scope: Usually contained within a single data center.
Differentiator: A SAN is a specialized network. Its sole purpose is to provide high-speed, block-level access between servers and storage systems, separate from the regular user traffic on the LAN.
