Networking Overview 1.1

Unit 1: Networking Concepts

1.1 Introduction to Networking

• Definition of a Network: A network consists of two or more computer systems linked by a transmission medium that share protocols for exchanging data.

• Components of a Network:

  • Nodes: Devices that send, receive, and forward data.

    • Intermediate Nodes: Responsible for forwarding functions (e.g., routers).

    • End Systems/Hosts: Send and receive the actual data traffic (e.g., PCs, smartphones).

  • Links: The communication pathways that connect nodes.

1.1.2 Types of Networks

1.2.1 Client-Server Networks

• Client: A device that consumes services provided by a server.

• Server: A more powerful computer making applications and resources available to clients.

• Characteristics:

  • Centralized management of application services and resources.

  • Majority of nodes function as clients, with servers granting access to resources.

1.2.2 Peer-to-Peer Networks

• Definition: Each host acts as both client and server.

• Characteristics:

  • Decentralized structure where service management is distributed among nodes.

  • Small peer-to-peer networks are sometimes called workgroups.

1.3 Appliances, Applications, and Functions

1.3.1 Appliances

• Definition: Specialized platforms designed for specific network roles. Examples include:

  • Switches: Forward data between devices.

  • Routers: Connect different networks and route data.

  • Firewalls: Enforce security rules.

  • Load Balancers and Proxies: Improve network performance.

• Deployment Types:

  • Physical Appliances: Run on dedicated hardware.

  • Virtual Appliances: Run as virtual machines on a hypervisor.

1.3.2 Applications

• Purpose: Services that allow networks to perform tasks like file sharing and email usage.

1.3.3 Functions

• Addition of Properties: Networks can be configured for specific tasks, enhancing their functionality, including:

  • Virtual Private Networks (VPN): Enable secure connections over the Internet.

  • Quality of Service (QoS): Optimizes the network for time-sensitive applications (e.g., video, voice).

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1.4 Network Types

1.4.1 Local Area Networks (LAN)

• Definition: Networks confined to a single geographical location.

• Examples:

  • Home/Residential Network: Typical internet router with connected devices.

  • Small Office/Home Office (SOHO) Network: Centralized server with client devices for business use.

  • Small and Medium-sized Enterprise (SME) Network: Structured cabling with multiple routers/switches.

  • Enterprise LAN: Large-scale network with extensive infrastructure and hundreds/thousands of devices.

  • Datacenter: Hosting only servers and storage without end-user client devices.

1.4.2 Wide Area Networks (WAN)

• Definition: Networks connecting multiple local networks across larger geographical areas.

• Characteristics:

  • Used to connect branch offices and allow remote access via the Internet.

1.5 Network Topology

1.5.1 Physical Topology

• Definition: The actual layout of nodes and how they are interconnected through transmission media.

• Example Types: Direct connections (e.g., single cable) or connections via switches with separate cables.

1.5.2 Logical Topology

• Definition: The way data flows within the network regardless of physical connections.

1.5.3 Point-to-Point Link

• Definition: Direct link between two nodes, ensuring dedicated bandwidth.

• Characteristics: Can be physical or logical, offering a 1:1 connection.

1.5.4 Star Topology

• Definition: Each node connects to a central forwarding device (e.g., switch/router).

• Advantages:

  • Easy to troubleshoot and reconfigure due to centralized monitoring.

  • Faults can be isolated effectively.

• Hub-and-Spoke Topology: A variation often used in WANs with a central hub connecting remote sites.

1.5.5 Mesh Topology

• Definition: Each device is interconnected, typically used in larger WANs.

• Full Mesh: Every device has a direct point-to-point link to every other device (impractical for large networks).

• Partial Mesh: Only critical devices are interconnected, providing redundancy and fault tolerance through intermediary links.