Network Topologies and Communication

Topologies Overview

• Topology: Layout of how a network communicates with devices.
• Common Topologies:
  • Star Topology: All devices connected to a central hub/switch.
    • Advantages: Fault-tolerant if one device/cable fails.
    • Disadvantages: Single point of failure if hub/switch fails.
  • Bus Topology: Devices connected to a single cable/backbone.
    • Advantages: Cost-effective, easy to implement.
    • Disadvantages: Requires terminators; signal reflection if open.
  • Ring Topology: Devices connected in a closed loop.
    • Advantages: Easy to install and troubleshoot.
    • Disadvantages: Single point of failure can disrupt all data flow.
  • Mesh Topology: Each device connected to every other device.
    • Advantages: High redundancy, fault-tolerant.
    • Disadvantages: Expensive, complex.
  • Hybrid Topology: Combines characteristics of different topologies.
    • Examples: Star-ring, star-bus networks.

Point-to-Point and Client-Server Topologies

• Point-to-Point: Direct connection between two hosts.
• Client-Server: Clients connect to a central server for resources.
• Peer-to-Peer: Clients share resources with each other without a central server.

Connectors and Cables

• RJ-11: 4-wire connector for telephone equipment.
• RJ-45: 8-wire connector for network connections.
• BNC Connector: Used on coaxial cables for video/audio.
• Fiber Optic Connectors: MTRJ, ST, LC, SC.
• Coaxial Cables: RG-6 for long distances, RG-59 for short distances.
• Fiber Optics: Single-mode for long distances, multimode for short.
• Cable Categories: CAT 3, 5, 5e, 6, 6A for varying speeds and applications.

Networking Devices

Hubs, Switches, and Routers

• Hubs: Basic device, broadcasts data to all ports.
• Switches: Intelligent device, directs data to specific ports.
• Routers: Directs data between networks, gateway functionality.

Firewalls and Security

• Firewalls: Prevent unauthorized access, use access control lists (ACLs).
• Stateful vs. Stateless Firewalls: Stateful tracks connections, Stateless uses ACLs.

IP Addressing and Subnetting

IP Address Basics

• IPv4: 32-bit, 4 octets, over 4 billion addresses.
• IPv6: 128-bit, uses hexadecimal, 340 undecillion addresses.

Subnetting

• Subnet Mask: Defines network and host portions of an IP address.
• Classful Addressing: Classes A, B, C for different organization sizes.
• Private vs. Public IP Addresses: Private used within networks, not accessible over the internet.

Protocols and Standards

Common Protocols

• TCP/IP: Foundation of internet communication.
• UDP: Connectionless, faster but no delivery guarantee.
• FTP, TFTP, SFTP: File transfer protocols with varying security levels.
• SMTP, POP3, IMAP4: Email sending and receiving protocols.

Security Protocols

• SSL/TLS: Secure data transfer protocols.
• IPsec: Secures IP communications, two modes: transport and tunnel.

Network Management and Tools

Network Tools

• Ping/Traceroute: Test connectivity and route paths.
• Ipconfig/Ifconfig: Display network interface information.
• Netstat: Display network connections.

Troubleshooting

• Identifying Issues: Symptoms, affected areas, changes.
• Solving Problems: Simple solutions first, plan and apply solutions.
• Documentation: Record problems and solutions for future reference.

Summary

• This lecture covered all aspects of network topologies, devices, IP addressing, protocols, management, and troubleshooting techniques important for network design and maintenance.