Introduction to Networks - Chapter 1 & 2

Chapter 1: Introduction to Networks

• Networks connect devices globally for communication, learning, work, and entertainment.
• Communication methods include texting, social media, online collaboration, blogs, and gaming.

Chapter 2: Types of Networks

• LAN (Local Area Network): Covers small geographic areas like homes, offices, or campuses, with high-speed bandwidth and single administration.
• WAN (Wide Area Network): Connects LANs over large geographic areas (cities, countries), managed by multiple service providers with slower speeds.
• Internet: A global network of interconnected LANs and WANs using copper, fiber optic, and wireless media.

Chapter 2: Network Components

• End Devices: Devices like computers and phones where messages originate or are received.
• Intermediary Devices: Devices like routers, switches, and firewalls that manage data flow.
• Media Types: Copper cables, fiber optics, and wireless technologies.

Chapter 2: Network Architectures

• Fault Tolerance: Redundancy mechanisms to minimize failures in a network.

Chapter 2: Networking Trends

• BYOD (Bring Your Own Device): Employees using personal devices to access company resources.
• Cloud Computing: Storing and accessing data over the internet (public, private, hybrid clouds).
• Online Collaboration and Video Communication: Tools for virtual teamwork (e.g., Cisco WebEx, TelePresence).
• Smart Homes: Integrating technology into appliances.

Chapter 2: Security

• Threats: External (viruses, hacking, DoS attacks) and Internal (accidental or intentional breaches by employees).
• Solutions: Home network security (antivirus, firewalls), and large network security (access control lists, intrusion prevention systems, VPNs).

Chapter 2/1: Key Topics on Networking

• Communication Rules: Require sender, receiver, and medium (channel). Protocols define message formatting, timing, delivery, and acknowledgment.
• Data Encapsulation: Data is wrapped in protocol layers (frame, packet) like envelopes.
• Network Protocols and Standards: Protocols like TCP/IP and OSI ensure interoperability and define communication standards.
• Common Protocols: HTTP (web communications), TCP (manages data segments), and IP (assigns source and destination addresses).

Chapter 2/1: Data Encapsulation

• Data travels through layers during encapsulation (sender) and de-encapsulation (receiver). (Application to segments to packets to frames).

Chapter 2/1: Addressing

• IP Address: Identifies source and destination for end-to-end delivery.
• MAC Address: Provides data link delivery within a network.
• Local Network Access: Data link frames are sent directly.
• Remote Network Access: Frames use a default gateway (router).

Chapter 2/1: Reference Models

• OSI Model: Seven layers (Application, Presentation, Session, Transport, Network, Data Link, Physical).
• TCP/IP Model: Four layers (Application, Transport, Internet, Network Access).

Chapter 2/1: Network Security

• Goals: Confidentiality (authorized access only), Integrity (prevent data alteration), and Availability (reliable access for authorized users).
• Threats: External (viruses, attacks, data theft), and Internal (human errors, malicious activity).

Chapter 2/1: Network Types

• LAN: Local Area Network.

Chapter 2/1: Emerging Trends

• BYOD (Bring Your Own Device)
• Cloud Computing
• Online Collaboration and Video Communication

Chapter 2/1: Internet Structure

• LANs and WANs connect through ISPs.
• Intranet/Extranet: Private networks for internal or external authorized users.

Chapter 2/2: Cisco IOS Overview

• Cisco IOS: Operating system for network devices (routers, switches).
• Command-line Interface (CLI) for device management.

Chapter 2/2: Cisco IOS Command Modes

• User EXEC Mode: Basic commands (view-only); Switch>.
• Privileged EXEC Mode: Advanced commands; Switch#.
• Global Configuration Mode: Device-wide settings; Switch(config)#.
• Sub-configuration Modes: Interface and Line Modes for specific settings of devices and access.

Chapter 2/2: Important Commands

• Moving between command modes.

Chapter 2/2: Security Configuration

• Password Security
• Secure console and privileged EXEC mode with secret passwords.
• Save configurations with copy running-config startup-config

Chapter 3: Network Layer Overview

• Networks handles end-to-end communication, addressing, encapsulation, routing, and de-encapsulation.
• Internet Protocol (IP): The most commonly used protocol (IPv4, IPv6).

Chapter 3: Characteristics of IP

• Connectionless Protocol: Does not require prior connection establishment before sending packets.
• Best Effort Delivery: Does not guarantee packet delivery or order. (Errors handled by upper layers)
• Media Independent: Operates over various media types.

Chapter 3: IPv4 and IPv6 Packets

• IPv4 header fields: Version, time to live (TTL), and source/destination IP.

Chapter 3: IPv4 Header Enhancements

• Simplified structures for faster processing
• Larger address space (128-bit addresses)
• Eliminates the need for NAT

Chapter 3: Host Routing Decisions

• Hosts use the network layer to send packets locally or remotely via a default gateway.

Chapter 3: Routing Tables

• Host Routing Table (routers store default gateway & known routes).
• Router Routing Table (Active interfaces, Local Routes (IP addresses assigned to interfaces), Remote Routes learned via manual or dynamic protocols).
• Router Anatomy: Contains crucial components (CPU, RAM, ROM, NVRAM, and Flash memory). RAM stores running configuration.

Chapter 3: Router Operation

• POST (Power-On Self Test) - diagnostics
• Load Bootstrap - copies from ROM to RAM.
• Load IOS - Load the operating system from Flash to RAM.
• Load Configuration - startup config from NVRAM to RAM or setup.

Chapter 3: Configuring a Router

• Initial setup configurations (device naming, secure console, SSH and Telnet, save configurations).

Chapter 4: IPv4 Addressing Basics

• IPv4 addresses are 32-bit binary numbers (composed into 4 octets, example: 192.168.1.1).
• Address components (Network Portion, Host Portion, and Subnet Mask).

Chapter 4: Address Types

• Unicast, Broadcast, and Multicast

Chapter 4: IPv4 Address Categories

• Public: routable on the internet
• Private: not routable externally

Chapter 4: Special Use Addresses

• Loopback (127.0.0.0/8): Tests local stack
• Link-Local (169.254.0.0/16): Autoconfigured, DHCP fails
• Test-Net (192.0.2.0/24): Reserved for teaching

Chapter 4: IPv4 Address Classes

• Class A, B, and C

Chapter 4: CIDR and Subnetting

• CIDR (Classless Inter-Domain Routing)
• Allows flexible subnetting

Chapter 4: ICMP and Connectivity Verification

• ICMP (Internet Control Message Protocol)
• Diagnostic tools (ping, traceroute)

Chapter 4: Testing Tools

• Ping: Tests connectivity
• Traceroute: Displays path and delay

Chapter 4: Conversions Between Binary and Decimal

• Binary to Decimal (value using powers of 2)
• Decimal to Binary (subtract largest power of 2)

Chapter 4: Practical Usage

• Static IP: Assigned manually
• Dynamic IP: Assigned automatically by DHCP.

Chapter 5: Subnetting

• Subnetting: Dividing larger networks into smaller broadcast domains (subnets).
• Improves network performance, manageability, and security by isolating devices.

Chapter 5: Principles of Subnetting

• Network and Host Portions: Subnet mask defines how many bits are used for network and host portions.
• Borrowed Host Bits (more bits borrowed → more subnets, fewer hosts per subnet).

Chapter 5: Formulas for Subnetting

• Number of Subnets (2⁸, etc.)
• Number of Hosts per Subnet (2⁵ - 2, etc.)

Chapter 5: Subnetting Examples

• /25, /26, /27 Subnets

Chapter 5: Variable Length Subnet Masking (VLSM)

• Efficient use of IP addresses, and hierarchical addressing and scalable network designs.
• Addresses of different sizes.

Chapter 5: Structured Addressing

• End-user devices (use DHCP for dynamic assignment)
• Servers (static IP for reliability)

Chapter 5: Practical Tools for Subnetting

• Magic Number Technique to calculate subnet ranges

Chapter 5: Address Planning

• Assigning IP addresses logically (e.g., by location or department)
• Separating device types in assignments.

Chapter 6: Static Routing Basics

• Definition: Manually configured routes in the routing table
• Advantages; Enhanced Security, resource-efficient
• Disadvantages: Time-consuming, Error-Prone
• Types of Static Routes (Standard, Default, and Floating)
• Use Cases (Small networks, stub networks, handle undefined destinations)

Chapter 6: Configuring Static Routes

• Basic commands.

Chapter 7: Dynamic Routing

• Definition: Routing protocol automatically discovers and maintains routing information.
• Purpose: Discover remote networks, Maintain up-to-date routing tables, Determine best paths to destinations, and adjust to network changes by finding new paths
• Advantages: Reduced administrative overhead, automatic adaptability to topology changes; Suitable for large & complex networks
• Disadvantages: Requires router resources, Slower convergence, increased Complexity

Chapter 7: Types of Dynamic Routing Protocols

• Distance-Vector (RIP, EIGRP): Share routing updates, incomplete network topology view.
• Link-State (OSPF, IS-IS): Build complete network topology maps, faster convergence.
• Hybrid Protocols (EIGRP): Combine features of both distance-vector & link-state.

Chapter 7: Routing Protocol Classifications

• Classful vs. Classless (RIPv1, IGRP vs. RIPv2, EIGRP, OSPF).
• Interior Gateway Protocols (IGP) inside Autonomous Systems (RIP, EIGRP, OSPF).
• Exterior Gateway Protocols (EGP) between Autonomous systems (BGP)

Chapter 7: Key Metrics in Routing Protocols

• Hops, Bandwidth, Delay, Reliability, Load (determining best path)

Chapter 7: More Protocols (RIP, EIGRP, OSPF, IS-IS)

• Their characteristics and purposes

Chapter 7: Routing Table Concepts & Lookup Process

• Routing Types (Directly Connected, Static, Dynamically Learned Routes)
• Lookup Process searches for longest prefix - lowest administrative distance.

Chapter 7: Administrative Distance

• Determines routing source reliability based on a range of values (0 to 255). e.g., a directly-connected route has a distance of 0.

Chapter 7: Convergence

• When all routers have complete & accurate routing information.
• Different protocols (distance-vector, link-state) have differing convergence speeds. e.g., OSPF converges faster than RIP.

Chapter 8: Open Shortest Path First (OSPF)

• Definition: A link-state routing protocol within an Autonomous System.
• Features (Fast Convergence & Scalability, Supports VLSM & CIDR, Uses cost as a metric)
• OSPF Operations (Link-State Advertisements (LSAs). Routers exchange this information.
• Neighbor Adjacencies (discovery).
• OSPF Metrics (Cost = Ref Bandwidth / Interface Bandwidth).

Chapter 8: OSPF Components

• Router ID (RID): Unique identifier for each OSPF router (determined by highest IP address on a loopback interface or highest active physical interface).
• OSPF Packets (Hello Packets discover neighbours & elect DR/BDR, LSUs).
• Areas(Single Area OSPF (simplifies network design by using one area for all routers)

Chapter 8: OSPF Configuration Steps

• Enabling OSPF on the router.

Explore the fundamentals of networks, including their types, components, and architectures in this quiz covering Chapters 1 and 2. Learn how LANs and WANs function, along with the essential devices and media that facilitate communication and data flow.