Connectivity Models

Network Types: Isolated vs Purpose-built Network

Isolated Network

• An isolated network is a standalone network without a connection to external systems or the internet. It is completely self-contained and often used in environments where security and privacy are the most important. Devices in an isolated network cannot communicate with external networks, ensuring maximum security by preventing external access or data breaches.

• In today’s interconnected world, the reliability and security of network communications are important for many environments. Some environments need very strict security measures due to the critical nature of their operations and the sensitivity of the data they handle.

• Some common use cases of isolated networks.

  • Military or Defense Networks: Security is critical

  • Industrial Control Systems: For example, Supervisory Control and Data Acquisition (SCADA). Operation Continuity is essential

  • Research environments: dealing with sensitive data

Purpose-built Network

• A purpose-built network is a semi-isolated network that is designed for a specific purpose or purposes. It maintains controlled connections with other networks while still providing some isolation.

• Businesses today face the challenge of ensuring secure internal communication while maintaining necessary external connectivity.

• Some use cases:

  • Corporate environments: internal deparments need secure, isolated communication, but also need internet access

  • Healthcare Systems: Patient data must be protected but external communication for medical resesarch and collaboration is necessary

  • Financial Institutions: Transactional data must be secure but still need connectivity for market interactions

Network Architectures: Two-tier vs Three-tier Hierarchical model

Two-tier

• Businesses today face the challenge of ensuring secure internal communication while maintaining necessary external connectivity.

• The access tier (also called the client tier) handles direct interactions with end users and provides access to network resources. This layer includes devices and systems that connect to the network to access services or data.

• The following list describes the components of the access tier:

  • Workstations: These components are end-user computers and devices.

  • User devices: These components aare user laptops, mobile devices, and desktops.

  • Access points: These components are switches and wireless access points that connect end-user devices to the network.

• The core tier (also called the server tier) manages network resources, services, and data. This layer handles the storage, processing, and management of data and services that the client tier accesses.

• The following list describes the components of the core tier:

  • Servers: These computers provide services or resources like file storage, application hosting, and database management.

  • Network devices: Core switches, routers, and other devices facilitate data flow between the client tier and external networks.

Three-tier

• The three-tier hierarchical model is a network architecture that organizes network components into three distinct layers: access tier (edge layer), distribution tier (aggregation layer), and core tier (backbone layer). Each tier has specific roles and responsibilities. By structuring network functions into separate tiers, this model improves scalability, manageability, and performance.

• The access tier provides connectivity for end-user devices and manages local network access.

• The following list describes access tier components:

  • Access switches: These switches connect end-user devices (for example, computers and printers) to the network.

  • Wireless access points: These components provide wireless connectivity for mobile devices.

  • Network interface cards: These cards facilitate network connections (found in user devices).

• The distribution tier aggregates and routes traffic between the access and core layers. It handles policy enforcement and network management.

• The following list describes distribution tier components:

  • Distribution switches: These switches connect multiple access switches and route traffic to and from the core layer.

  • Routers: Routers manage routing and traffic flow between network segments, such as subnets or VLANs.

  • Firewalls: Firewalls implement security policies and control traffic flow between network segments.

• The core tier provides high-speed, high-capacity connectivity between different distribution layers and handles the primary data transport and network backbone functions.

• The following list describes the core tier components:

  • Core switches: These high-performance switches connect different distribution layers and provide fast data transfer.

  • High-speed routers: These routers manage large traffic volumes and ensure efficient routing between different parts of the network, such as LANs, WANs, data centers, and ISPs.

  • Data center interconnects: These components provide connectivity between data centers and other core network components.

Two-Tier vs Three-Tier

• In the network design, two-tier and three-tier hierarchical models are used to manage data flow and connectivity. Each hierarchy model offers distinct advantages. Understanding their differences is important for selecting the optimal architecture for a specific network environment.

• The evolution from a two-tier to a three-tier topology involves moving from a flat, scalable network structure with a collapsed core layer (spine-leaf) to a more hierarchical model with separate core, distribution, and access layers. This change enhances control and aggregation but increases complexity. Transitioning from a two-tier to a three-tier topology can also improve scalability by optimizing traffic, providing better control over network segments, and linking data centers through core layers.

Single-site vs Multi-site

Single-site

• A single-site network architecture involves a centralized infrastructure where all networking resources, data storage, and applications are housed within a single physical location. This setup is typically used by organizations with a single office or centralized operations.

• The advantages of a single-site network architecture are as follows:

  • Centralized management: All resources and IT staff are located in one place, simplifying management and maintenance. This centralization enables efficient network control and monitoring.

  • Reduced latency: Data transmission within the same location experiences minimal latency, leading to faster resource access and improved performance for local users.

  • Cost efficiency: Initial setup and operational costs can be lower when compared to multiple locations requiring networking infrastructure and IT staff.

  • Simplified troubleshooting: Easier identification and resolution of network issues due to the localized infrastructure.

  • Enhanced security: Physical security measures are easier to implement and enforce when all critical infrastructure is housed in one location.

Multi-site

• A multi-site network architecture distributes networking resources, data storage, and applications across multiple physical locations. This setup is commonly used by organizations with multiple offices, branches, or remote operations that require a unified network infrastructure across different geographical areas.

• The advantages of a multi-site network architecture are as follows:

  • Distributed redundancy: Multi-site architecture offers built-in redundancy by spreading resources across multiple locations. This approach minimizes the risk of a single point of failure and enhances overall network resilience and availability.

  • Geographical flexibility: Users in different locations can access local resources, which reduces latency and improves performance. This setup is ideal for organizations with a geographically dispersed workforce.

  • Scalability: Expanding the network is more straightforward because additional sites can be integrated into the existing architecture, allowing organizations to grow without a significant infrastructure upgrade.

  • Disaster recovery: With resources distributed across multiple locations, organizations can implement more robust disaster recovery plans and ensure that data and services remain accessible even if one site experiences an outage.

  • Localized resource management: Each site can manage its resources while still being part of the larger network, allowing tailored solutions that meet specific regional or departmental needs.