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1.2 Describe characteristics of network topology architectures

1.2.a Two-tier

The two-tier network architecture, also known as the collapsed core architecture, is a simplified network design commonly used in small to medium-sized networks. It consists of two layers: the Access layer and the Distribution layer.

Access Layer: This is the layer where end devices (like computers and printers) connect to the network. It provides access to the network for devices and handles data traffic between end devices and higher layers.

Distribution Layer: This layer acts as an intermediary between the Access layer and the Core. In the two-tier model, the Core layer is collapsed into the Distribution layer, meaning the Distribution layer also handles high-speed routing and switching for the network.

This architecture is cost-effective and easier to manage, making it suitable for smaller networks. However, it may not scale well for larger enterprises.

two tier architecture

1.2.b Three-tier

The three-tier architecture is a more scalable and resilient network design typically used in larger enterprise networks. It includes three distinct layers: Core, Distribution, and Access.

Core Layer: This is the backbone of the network, providing high-speed data transport between different distribution layers. It is optimized for fast and reliable data forwarding.

Distribution Layer: This layer aggregates data from the Access layer and provides policy-based connectivity. It handles routing between VLANs and manages traffic for security and performance optimization.

Access Layer: Similar to the two-tier model, the Access layer connects end devices to the network. It handles device authentication, VLAN assignments, and PoE (Power over Ethernet) where required.

This architecture offers better scalability, flexibility, and redundancy, making it ideal for large, complex networks.

tree tier architecture

1.2.c Spine-Leaf

The Spine-Leaf architecture is a modern network topology used primarily in data centers to provide high-speed, low-latency networking. It consists of two layers: Spine and Leaf.

Spine Layer: This layer consists of high-speed switches that connect to every Leaf switch in the network. The Spine layer is responsible for fast data forwarding and ensures that all Leaf switches are interconnected with minimal hops.

Leaf Layer: The Leaf switches connect directly to the end devices (like servers and storage) and to the Spine switches. Every Leaf switch connects to every Spine switch, creating a non-blocking, full-mesh topology.

This architecture is highly scalable and supports east-west traffic patterns commonly found in modern applications and cloud services. It is especially useful in environments where predictable performance and low latency are critical.

Spine-Leaf architecture

1.2.d WAN (Wide Area Network)

WAN (Wide Area Network) is a network that spans a large geographical area, connecting multiple LANs (Local Area Networks) across cities, states, or even countries. WANs use various technologies to transmit data over long distances, including leased lines, MPLS (Multiprotocol Label Switching), and VPNs (Virtual Private Networks).

Core Components: Routers, switches, and telecommunications infrastructure (like fiber optic cables) are commonly used in WANs to ensure data can travel efficiently over vast distances.

Connectivity: WANs rely on public or private telecommunication services and use protocols like IP (Internet Protocol) to ensure data reaches its destination securely and reliably.

WANs are essential for businesses that need to connect multiple offices or provide access to centralized resources over a broad area.

1.2.e Small Office/Home Office (SOHO)

The Small Office/Home Office (SOHO) network topology is designed for small-scale networks, typically used in home environments or small businesses. SOHO networks are characterized by simplicity and cost-effectiveness.

Components: SOHO networks usually consist of a single router providing both wired and wireless connectivity, a few switches, and connected devices like computers, printers, and smart devices.

Configuration: These networks are generally easy to set up, with plug-and-play devices and basic security features like firewalls and WPA2 encryption for wireless networks.

SOHO networks prioritize ease of use and require minimal technical expertise to maintain. They are ideal for personal use or small businesses with limited networking needs.

1.2.f On-premises and Cloud

On-premises and cloud refer to two different approaches to deploying network services and infrastructure.

On-premises: This refers to network resources (like servers, storage, and applications) that are physically located within an organization’s premises. The organization is responsible for managing and maintaining the infrastructure, providing greater control but also requiring more resources for management and security.

Cloud: In the cloud model, network services and infrastructure are hosted off-site by third-party providers (such as AWS, Microsoft Azure, or Google Cloud). The cloud provider manages the hardware and software, offering scalable, on-demand resources over the internet.

Each model has its advantages: On-premises solutions offer greater control and may be preferred for sensitive data or applications, while cloud solutions provide flexibility, scalability, and reduced capital expenditure, making them ideal for dynamic workloads and fast-growing businesses.