Network Architecture

Introduction

Network architecture is the conceptual design and structured framework that defines the physical components, their functional organization and configuration, operational principles, and procedures, and the data formats used in its operation. In simpler terms, it is the master blueprint that specifies how a network is organized and how the components (hardware, software, protocols) work together to facilitate communication.

It moves beyond individiual protocols and addresses the big-picture questions: How is the network laid out? How is traffic managed? How is growth handled? How are security and performance balanced?

Core Architectural Models

There are tow fundamental models that define the logical structure of a network.

1 Client-Server Model

Definition:

A centralized network model where powerful computers (servers) provide dedicated services and resources to less powerful computers (clients) upon request.

In the client-server architecture, computers are divided into two distinct roles:

• Servers – Powerful machines that provides services or resources (like websites, files, databases).
• Clients – User devices (PCs, laptops, smartphones) that request and use those services.

How It Works

1. A client (e.g., your laptop) requests a service (e.g., a webpage).
2. The server (e.g., a web server) receives the request, processes it, and return the response.
3. The client consumes the service.

Example:

When you type www.example.com into a browser, your browser (the client) requests the page, and the web server delivers it.

Characteristics:

• Centralized Management: User accounts, security, and resources are managed from a central point, making administration easier and more secure.
• Scalable: New clients can be added with minimal impact on performance. Server hardware can be upgraded or new servers can be added to handle more load.
• Powerful Services: Dedicated servers can handle complex, resource-intensive tasks (e.g., databases, email, authentication).
• Higher Cost: Requires dedicated server hardware, software, and often specialized IT staff to manage it.
• Single Point of Failure: If a critical server goes down, the services it provides become unavailable to all clients.

Real-World Examples

• Web browsing (HTTP servers)
• Email systems (mail servers)
• Banking systems
• Corporate databases

2 Peer-to-Peer (P2P) Model

Definition:

A decentralized network model where each device ( a “peer”) has equal capabilities and responsibilities. There is no dedicated server; each computer can function as both a client and a server.

Each peer can request services and also provide services to others.

How It Works:

1. A peer looks for a resource (e.g., a file).
2. Instead of contacting a central server, it connects directly to another peer that has the resource.
3. The peers exchange data without a central authority.

Example:

When using BitTorrent, your computer downloads pieces of a file from multiple peers while also uploading pieces you already have.

Characteristics:

• Decentralized Control: No single server who manages the system. So, no single point of failure.
• Less Secure: Security and permissions are managed on each individual device, making it difficult to enforce consistent policies.

Real-World Examples:

• File sharing (BitTorrent, eMule)
• Voice-over-IP (early Skype versions)
• Blockchain and cryptocurrencies (Bitcoin, Ethereum)
• Distributed computing (SETI@home, Folding@home)

3 Hybrid Models

In practice, many systems blend the two approaches to balance strengths and weaknesses.

• Content Delivery Networks (CDNs): Servers distribute content globally but sometimes use P2P for faster delivery.
• Gaming Platforms: Online games often rely on central servers for matchmaking but allow peer-to-peer communication for in-game traffic.

Key Differences: Client-Server vs Peer-to-Peer

Advantages and Disadvantages

Client-Server

Advantages:

1. Centralized management of data
2. Easier to implement security and updates
3. Predictable peformance

Disadvantages:

1. High cost of servers and infrastructures
2. Single point of failure risks
3. Bottlenecks under heavy load

Peer-to-Peer

Advantages:

1. Highly scalable and fault-tolerant
2. Low setup cost
3. Efficient for large-scale file sharing and distributed workloads

Disadvantages:

1. Difficult to secure and regulate
2. Resource quality varies (depends on peers bandwidth and uptime)
3. Potential for illegal or malicious use

Choosing the Right Model

Use Client-Server when:

• You need central control (banking, e-commerce, enterprise systems)
• Security and reliability are critical
• Predictable performance is required.

Use Peer-to-Peer when:

• You want scalability with minimal cost.
• A decentralised system is desired (blockchain, file sharing).
• Resilience against single-point failures is important.