Notes on Network Engineering Lecture

Introduction

• Course developed by Brian Farrell from Edmonds College for Free Code Camp.
• Focus: Configuring, managing, and troubleshooting computer networks.
• Prepares for CompTIA's Network+ exam.

Layered Network Devices Overview

• Discussing layer 1, layer 2, and layer 3 devices.

OSI Model (Open System Interconnection Model)

1. Layer 1: Physical Layer
2. Layer 2: Data Link Layer
3. Layer 3: Network Layer
4. Layer 4: Transport Layer
5. Layer 5: Session Layer
6. Layer 6: Presentation Layer
7. Layer 7: Application Layer

Layer 1 Devices

• Devices operate at the physical layer.

Analog Modems

• Modem = Modulator-Demodulator.
• Converts digital signals to analog for transmission and vice versa.
• Operates only at Layer 1.

Hubs

• Concentrators that replicate electrical signals across all ports.
• Less common in modern networks.

Layer 2 Devices

Switches

• Utilize ASIC (Application Specific Integrated Circuit) to learn devices on the network.
• Communicate using MAC addresses.

Wireless Access Points (WAP)

• Bridge wireless and wired segments (commonly between 802.11 and Ethernet).

Layer 3 Devices

Multi Layer Switches

• Provide Layer 2 switching and Layer 3 routing capabilities.
• More common in enterprise local area networks.

Routers

• Connect different networks using Layer 3 logical network information.
• Use software for routing decisions, generally have fewer ports than switches.

Part 2: Security and Optimization Devices

Firewalls

• Can be software or hardware based.
• Operates at multiple OSI layers (2, 3, 4, and 7).
• Packets controlled via stateless and stateful inspection.

Intrusion Detection Systems (IDS)

• Passive monitoring for breaches, alerts via logs, and messages.
• Cannot prevent an attack.

Intrusion Prevention Systems (IPS)

• Actively stop breaches through various actions (block IPs, terminate sessions).

VPN Concentrators

• Allow secure VPN connections, operate at layers 2, 3, and 7.
• Provide IPsec encryption.

Load Balancers and Proxy Servers

• Load Balancers: Distribute workloads among servers.
• Proxy Servers: Act on behalf of clients to retrieve resources and filter content.

Networking Services and Applications

Virtual Private Network (VPN)

• Provides encrypted connections over public networks.
• Types: Site-to-site, remote access, host-to-host.

VPN Protocols

• IPsec: Suite of protocols for securing VPN connections.
• GRE: Tunneling protocol for encapsulating other protocols.
• PPTP: Older VPN technology, less secure.

Dynamic Host Configuration Protocol (DHCP)

• Handles dynamic IP address assignments, reducing manual configuration.
• DHCP process involves discovery, offer, request, and acknowledgment packets.

Introduction to Domain Name System (DNS)

DNS Functionality

• Maps human-friendly names to IP addresses.
• Structure includes various DNS servers (local, TLD, root, authoritative).

DNS Records

• A records: Map hostnames to IPv4 addresses.
• AAAA records: Map hostnames to IPv6 addresses.
• CNAME: Maps to canonical names.
• MX: Determines email server routing.

Dynamic DNS

• Allows for real-time updates to DNS records for changing IPs.

Network Address Translation (NAT)

Purpose and Functionality

• Converts private IP addresses to public IPs for routing on the internet.
• Types: Static NAT, Dynamic NAT, and Port Address Translation (PAT).

WAN Technologies

Public Switched Telephone Network (PSTN)

• Used for dial-up connections and ISDN.

DSL: Digital Subscriber Line

• Offers better speeds than PSTN.

Broadband Cable

• Shares bandwidth among users, must meet DOCSIS standards.

Fiber Optic Networking

• Utilizes light for data transmission, highly efficient, low interference.

Wireless Technologies

GSM and CDMA

• Different standards for connecting devices to cellular networks.

WiMAX and Satellite Connections

• Alternatives for broadband where traditional means are unavailable.

Network Cabling

Twisted Pair, Coaxial, and Fiber Optic

• Twisted Pair: Commonly used, types include UTP and STP.
• Coaxial: Used for older Ethernet standards.
• Fiber Optic: Higher speed, longer distances, immune to electromagnetic interference.

Network Topologies

• Physical vs. Logical Topology.
• Types: Bus, Ring, Star, Mesh, Hybrid.

Network Infrastructure Implementations

Categories of Networks

• LAN, MAN, WAN, PAN, Hybrid, and SCADA networks.

Introduction to IPv4

Purpose and Properties

• IPv4: 32-bit addresses, logical, uses subnet masks for routing.

Classes of Addresses

• Class A, B, C, D; private vs. public addresses.

Introduction to IPv6

Structure and Features

• 128-bit addresses, hexadecimal representation, auto-configuration.

Network Monitoring and Analysis

Why Monitoring is Essential

• To ensure network health and performance.

Tools and Techniques

• Log files, SNMP, Syslog, performance monitoring tools.

Active Network Monitoring Tools

• Port Scanners and Packet Sniffers for vulnerability assessment.

Wireless Monitoring Tools

• Wi-Fi analyzers and survey tools for network design and performance improvement.

Environmental Monitoring

• Monitoring power, temperature, and humidity to ensure optimal conditions for network equipment.