Introduction to Networks Companion Guide (CCNAv7) by Cisco Networking Academy (z-lib.org)(1) (1).pdf

Contents 1. Cover Page 2. About This eBook 3. Title Page 4. Copyright Page 5. About the Contributing Authors 6. Contents at a Glance 7. Reader Services 8. Contents 9. Command Syntax Conventions 10. Introduction 1. Who Should Read This Book 2. Book Features 3. How This Book Is Organized 11. Figure Credits 12. Chapter 1. Networking Today 1. Objectives 2. Key Terms 3. Introduction (1.0) 4. Networks Affect Our Lives (1.1) 5. Network Components (1.2) 6. Network Representations and Topologies (1.3) 7. Common Types of Networks (1.4) 8. Internet Connections (1.5) 9. Reliable Networks (1.6) 10. Network Trends (1.7) 11. Network Security (1.8) 12. The IT Professional (1.9) 13. Summary (1.10) 14. Practice 15. Check Your Understanding Questions 13. Chapter 2. Basic Switch and End Device Configuration 1. Objectives 2. Key Terms 3. Introduction (2.0) 4. Cisco IOS Access (2.1) 5. IOS Navigation (2.2) 6. The Command Structure (2.3) 7. Basic Device Configuration (2.4) 8. Save Configurations (2.5) 9. Ports and Addresses (2.6) 10. Configure IP Addressing (2.7) 11. Verify Connectivity (2.8) 12. Summary (2.9) 13. Practice 14. Check Your Understanding Questions 14. Chapter 3. Protocols and Models 1. Objectives 2. Key Terms 3. Introduction (3.0) 4. The Rules (3.1) 5. Protocols 6. Protocol Suites (3.3) 7. Standards Organizations (3.4) 8. Reference Models (3.5) 9. Data Encapsulation (3.6) 10. Data Access (3.7) 11. Summary (3.8) 12. Practice 13. Check Your Understanding Questions 15. Chapter 4. Physical Layer 1. Objectives 2. Key Terms 3. Introduction (4.0) 4. Purpose of the Physical Layer (4.1) 5. Physical Layer Characteristics (4.2) 6. Copper Cabling (4.3) 7. UTP Cabling (4.4) 8. Fiber-Optic Cabling (4.5) 9. Wireless Media (4.6) 10. Summary (4.7) 11. Practice 12. Check Your Understanding Questions 16. Chapter 5. Number Systems 1. Objectives 2. Key Terms 3. Introduction (5.0) 4. Binary Number System (5.1) 5. Hexadecimal Number System (5.2) 6. Summary (5.3) 7. Practice 8. Check Your Understanding Questions 17. Chapter 6. Data Link Layer 1. Objectives 2. Key Terms 3. Introduction (6.0) 4. Purpose of the Data Link Layer (6.1) 5. Topologies (6.2) 6. Data Link Frame (6.3) 7. Summary (6.4) 8. Practice 9. Check Your Understanding Questions 18. Chapter 7. Ethernet Switching 1. Objectives 2. Key Terms 3. Introduction (7.0) 4. Ethernet Frames (7.1) 5. Ethernet MAC Address (7.2) 6. The MAC Address Table (7.3) 7. Switch Speeds and Forwarding Methods (7.4) 8. Summary (7.5) 9. Practice 10. Check Your Understanding Questions 19. Chapter 8. Network Layer 1. Objectives 2. Key Terms 3. Introduction (8.0) 4. Network Layer Characteristics (8.1) 5. IPv4 Packet (8.2) 6. IPv6 Packet (8.3) 7. How a Host Routes (8.4) 8. Introduction to Routing (8.5) 9. Summary (8.6) 10. Practice 11. Check Your Understanding Questions 20. Chapter 9. Address Resolution 1. Objectives 2. Key Terms 3. Introduction (9.0) 4. MAC and IP (9.1) 5. ARP (9.2) 6. IPv6 Neighbor Discovery (9.3) 7. Summary (9.4) 8. Practice 9. Check Your Understanding Questions 21. Chapter 10. Basic Router Configuration 1. Objectives 2. Introduction (10.0) 3. Configure Initial Router Settings (10.1) 4. Configure Interfaces (10.2) 5. Configure the Default Gateway (10.3) 6. Summary (10.4) 7. Practice 8. Check Your Understanding Questions 22. Chapter 11. IPv4 Addressing 1. Objectives 2. Key Terms 3. Introduction (11.0) 4. IPv4 Address Structure (11.1) 5. IPv4 Unicast, Broadcast, and Multicast (11.2) 6. Types of IPv4 Addresses (11.3) 7. Network Segmentation (11.4) 8. Subnet an IPv4 Network (11.5) 9. Subnet a Slash 16 and a Slash 8 Prefix (11.6) 10. Subnet to Meet Requirements (11.7) 11. VLSM (11.8) 12. Structured Design (11.9) 13. Summary (11.10) 14. Practice 15. Check Your Understanding Questions 23. Chapter 12. IPv6 Addressing 1. Objectives 2. Key Terms 3. Introduction (12.0) 4. IPv4 Issues (12.1) 5. IPv6 Address Representation (12.2) 6. IPv6 Address Types (12.3) 7. GUA and LLA Static Configuration (12.4) 8. Dynamic Addressing for IPv6 GUAs (12.5) 9. Dynamic Addressing for IPv6 LLAs (12.6) 10. IPv6 Multicast Addresses (12.7) 11. Subnet an IPv6 Network (12.8) 12. Summary (12.9) 13. Practice 14. Check Your Understanding Questions 24. Chapter 13. ICMP 1. Objectives 2. Introduction (13.0) 3. ICMP Messages (13.1) 4. Ping and Traceroute Tests (13.2) 5. Summary (13.3) 6. Practice 7. Check Your Understanding Questions 25. Chapter 14. Transport Layer 1. Objectives 2. Key Terms 3. Introduction (14.0) 4. Transportation of Data (14.1) 5. TCP Overview (14.2) 6. UDP Overview (14.3) 7. Port Numbers (14.4) 8. TCP Communication Process (14.5) 9. Reliability and Flow Control (14.6) 10. UDP Communication (14.7) 11. Summary (14.8) 12. Practice 13. Check Your Understanding Questions 26. Chapter 15. Application Layer 1. Objectives 2. Key Terms 3. Introduction (15.0) 4. Application, Presentation, and Session (15.1) 5. Peer-to-Peer (15.2) 6. Web and Email Protocols (15.3) 7. IP Addressing Services (15.4) 8. File Sharing Services (15.5) 9. Summary 10. Practice 11. Check Your Understanding Questions 27. Chapter 16. Network Security Fundamentals 1. Objectives 2. Key Terms 3. Introduction (16.0) 4. Security Threats and Vulnerabilities (16.1) 5. Network Attacks (16.2) 6. Network Attack Mitigations (16.3) 7. Device Security (16.4) 8. Summary 9. Practice 10. Check Your Understanding Questions 28. Chapter 17. Build a Small Network 1. Objectives 2. Key Terms 3. Introduction (17.0) 4. Devices in a Small Network (17.1) 5. Small Network Applications and Protocols (17.2) 6. Scale to Larger Networks (17.3) 7. Verify Connectivity (17.4) 8. Host and IOS Commands (17.5) 9. Troubleshooting Methodologies (17.6) 10. Troubleshooting Scenarios (17.7) 11. Summary (17.8) 12. Practice 13. Check Your Understanding Questions 29. Appendix A. Answers to “Check Your Understanding” Questions 30. Key Terms Glossary 31. Index 32. 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However, support of ePUB and its many features varies across reading devices and applications. Use your device or app settings to customize the presentation to your liking. Settings that you can customize often include font, font size, single or double column, landscape or portrait mode, and figures that you can click or tap to enlarge. For additional information about the settings and features on your reading device or app, visit the device manufacturer’s Web site. Many titles include programming code or configuration examples. To optimize the presentation of these elements, view the e-book in single-column, landscape mode and adjust the font size to the smallest setting. In addition to presenting code and configurations in the reflowable text format, we have included images of the code that mimic the presentation found in the print book; therefore, where the reflowable format may compromise the presentation of the code listing, you will see a “Click here to view code image” link. Click the link to view the print-fidelity code image. To return to the previous page viewed, click the Back button on your device or app. Introduction to Networks Companion Guide (CCNAv7) Cisco Networking Academy Cisco Press Introduction to Networks Companion Guide (CCNAv7) Cisco Networking Academy Copyright © 2020 Cisco Systems, Inc. Published by: Cisco Press All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission from the publisher, except for the inclusion of brief quotations in a review. ScoutAutomatedPrintCode Library of Congress Control Number: 2020935402 ISBN-13: 978-0-13-663366-2 ISBN-10: 0-13-663366-8 Warning and Disclaimer This book is designed to provide information about the Cisco Networking Academy Introduction to Networks (CCNAv7) course. 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Singapore Europe Headquarters Cisco Systems International BV Amsterdam, The Netherlands Cisco has more than 200 offices worldwide. Addresses, phone numbers, and fax numbers are listed on the Cisco Website at www.cisco.com/go/offices. Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R) About the Contributing Authors Rick Graziani teaches computer science and computer networking courses at Cabrillo College and University of California, Santa Cruz in Santa Cruz, California. Prior to teaching, Rick worked in the information technology field for Santa Cruz Operation, Tandem Computers, and Lockheed Missiles and Space Corporation, and he served in the U.S. Coast Guard. He holds an M.A. in computer science and systems theory from California State University, Monterey Bay. Rick also works as a curriculum developer for the Cisco Networking Academy Curriculum Engineering team. When Rick is not working, he is most likely surfing at one of his favorite Santa Cruz surf breaks. Allan Johnson entered the academic world in 1999, after 10 years as a business owner/operator, to dedicate his efforts to his passion for teaching. He holds both an M.B.A. and an M.Ed. in training and development. He taught CCNA courses at the high school level for seven years and has taught both CCNA and CCNP courses at Del Mar College in Corpus Christi, Texas. In 2003, Allan began to commit much of his time and energy to the CCNA Instructional Support Team, providing services to Networking Academy instructors worldwide and creating training materials. He now works full time for Cisco Networking Academy as Curriculum Lead. Contents at a Glance Introduction Chapter 1 Networking Today Chapter 2 Basic Switch and End Device Configuration Chapter 3 Protocols and Models Chapter 4 Physical Layer Chapter 5 Number Systems Chapter 6 Data Link Layer Chapter 7 Ethernet Switching Chapter 8 Network Layer Chapter 9 Address Resolution Chapter 10 Basic Router Configuration Chapter 11 IPv4 Addressing Chapter 12 IPv6 Addressing Chapter 13 ICMP Chapter 14 Transport Layer Chapter 15 Application Layer Chapter 16 Network Security Fundamentals Chapter 17 Build a Small Network Appendix A Answers to “Check Your Understanding” Questions Key Terms Glossary Index Reader Services Register your copy at www.ciscopress.com/title/9780136633662 for convenient access to downloads, updates, and corrections as they become available. To start the registration process, go to www.ciscopress.com/register and log in or create an account*. Enter the product ISBN 9780136633662 and click Submit. 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Contents Introduction Chapter 1 Networking Today Objectives Key Terms Introduction (1.0) Networks Affect Our Lives (1.1) Networks Connect Us (1.1.1) No Boundaries (1.1.3) Network Components (1.2) Host Roles (1.2.1) Peer-to-Peer (1.2.2) End Devices (1.2.3) Intermediary Devices (1.2.4) Network Media (1.2.5) Network Representations and Topologies (1.3) Network Representations (1.3.1) Topology Diagrams (1.3.2) Physical Topology Diagrams Logical Topology Diagrams Common Types of Networks (1.4) Networks of Many Sizes (1.4.1) LANs and WANs (1.4.2) LANs WANs The Internet (1.4.3) Intranets and Extranets (1.4.4) Internet Connections (1.5) Internet Access Technologies (1.5.1) Home and Small Office Internet Connections (1.5.2) Businesses Internet Connections (1.5.3) The Converging Network (1.5.4) Reliable Networks (1.6) Network Architecture (1.6.1) Fault Tolerance (1.6.2) Scalability (1.6.3) Quality of Service (1.6.4) Network Security (1.6.5) Network Trends (1.7) Recent Trends (1.7.1) Bring Your Own Device (BYOD) (1.7.2) Online Collaboration (1.7.3) Video Communications (1.7.4) Cloud Computing (1.7.6) Technology Trends in the Home (1.7.7) Powerline Networking (1.7.8) Wireless Broadband (1.7.9) Wireless Internet Service Providers Wireless Broadband Service Network Security (1.8) Security Threats (1.8.1) Security Solutions (1.8.2) The IT Professional (1.9) CCNA (1.9.1) Networking Jobs (1.9.2) Summary (1.10) Networks Affect Our Lives Network Components Network Representations and Topologies Common Types of Networks Internet Connections Reliable Networks Network Trends Network Security The IT Professional Practice Check Your Understanding Questions Chapter 2 Basic Switch and End Device Configuration Objectives Key Terms Introduction (2.0) Cisco IOS Access (2.1) Operating Systems (2.1.1) GUI (2.1.2) Purpose of an OS (2.1.3) Access Methods (2.1.4) Terminal Emulation Programs (2.1.5) IOS Navigation (2.2) Primary Command Modes (2.2.1) Configuration Mode and Subconfiguration Modes (2.2.2) Navigate Between IOS Modes (2.2.4) A Note About Syntax Checker Activities (2.2.6) The Command Structure (2.3) Basic IOS Command Structure (2.3.1) IOS Command Syntax Check (2.3.2) IOS Help Features (2.3.3) Hot Keys and Shortcuts (2.3.5) Basic Device Configuration (2.4) Device Names (2.4.1) Password Guidelines (2.4.2) Configure Passwords (2.4.3) Encrypt Passwords (2.4.4) Banner Messages (2.4.5) Save Configurations (2.5) Configuration Files (2.5.1) Alter the Running Configuration (2.5.2) Capture Configuration to a Text File (2.5.4) Ports and Addresses (2.6) IP Addresses (2.6.1) Interfaces and Ports (2.6.2) Configure IP Addressing (2.7) Manual IP Address Configuration for End Devices (2.7.1) Automatic IP Address Configuration for End Devices (2.7.2) Switch Virtual Interface Configuration (2.7.4) Verify Connectivity (2.8) Summary (2.9) Cisco IOS Access IOS Navigation The Command Structure Basic Device Configuration Save Configurations Ports and Addresses Configure IP Addressing Verify Connectivity Practice Check Your Understanding Questions Chapter 3 Protocols and Models Objectives Key Terms Introduction (3.0) The Rules (3.1) Communications Fundamentals (3.1.2) Communication Protocols (3.1.3) Rule Establishment (3.1.4) Network Protocol Requirements (3.1.5) Message Encoding (3.1.6) Message Formatting and Encapsulation (3.1.7) Message Size (3.1.8) Message Timing (3.1.9) Message Delivery Options (3.1.10) A Note About the Node Icon (3.1.11) Protocols Network Protocol Overview (3.2.1) Network Protocol Functions (3.2.2) Protocol Interaction (3.2.3) Protocol Suites (3.3) Network Protocol Suites (3.3.1) Evolution of Protocol Suites (3.3.2) TCP/IP Protocol Example (3.3.3) TCP/IP Protocol Suite (3.3.4) Application Layer Transport Layer Internet Layer Network Access Layer TCP/IP Communication Process (3.3.5) Standards Organizations (3.4) Open Standards (3.4.1) Internet Standards (3.4.2) Electronic and Communications Standards (3.4.3) Reference Models (3.5) The Benefits of Using a Layered Model (3.5.1) The OSI Reference Model (3.5.2) The TCP/IP Protocol Model (3.5.3) OSI and TCP/IP Model Comparison (3.5.4) Data Encapsulation (3.6) Segmenting Messages (3.6.1) Sequencing (3.6.2) Protocol Data Units (3.6.3) Encapsulation Example (3.6.4) De-encapsulation Example (3.6.5) Data Access (3.7) Addresses (3.7.1) Layer 3 Logical Address (3.7.2) Devices on the Same Network (3.7.3) Role of the Data Link Layer Addresses: Same IP Network (3.7.4) Devices on a Remote Network (3.7.5) Role of the Network Layer Addresses (3.7.6) Role of the Data Link Layer Addresses: Different IP Networks (3.7.7) Data Link Addresses (3.7.8) Summary (3.8) The Rules Protocols Protocol Suites Standards Organizations Reference Models Data Encapsulation Data Access Practice Check Your Understanding Questions Chapter 4 Physical Layer Objectives Key Terms Introduction (4.0) Purpose of the Physical Layer (4.1) The Physical Connection (4.1.1) The Physical Layer (4.1.2) Physical Layer Characteristics (4.2) Physical Layer Standards (4.2.1) Physical Components (4.2.2) Encoding (4.2.3) Signaling (4.2.4) Bandwidth (4.2.5) Bandwidth Terminology (4.2.6) Latency Throughput Goodput Copper Cabling (4.3) Characteristics of Copper Cabling (4.3.1) Types of Copper Cabling (4.3.2) Unshielded Twisted-Pair (UTP) (4.3.3) Shielded Twisted-Pair (STP) (4.3.4) Coaxial Cable (4.3.5) UTP Cabling (4.4) Properties of UTP Cabling (4.4.1) UTP Cabling Standards and Connectors (4.4.2) Straight-Through and Crossover UTP Cables (4.4.3) Fiber-Optic Cabling (4.5) Properties of Fiber-Optic Cabling (4.5.1) Types of Fiber Media (4.5.2) Single-Mode Fiber Multimode Fiber Fiber-Optic Cabling Usage (4.5.3) Fiber-Optic Connectors (4.5.4) Fiber Patch Cords (4.5.5) Fiber Versus Copper (4.5.6) Wireless Media (4.6) Properties of Wireless Media (4.6.1) Types of Wireless Media (4.6.2) Wireless LAN (4.6.3) Summary (4.7) Purpose of the Physical Layer Physical Layer Characteristics Copper Cabling UTP Cabling Fiber-Optic Cabling Wireless Media Practice Check Your Understanding Questions Chapter 5 Number Systems Objectives Key Terms Introduction (5.0) Binary Number System (5.1) Binary and IPv4 Addresses (5.1.1) Binary Positional Notation (5.1.3) Convert Binary to Decimal (5.1.5) Decimal to Binary Conversion (5.1.7) Decimal to Binary Conversion Example (5.1.8) IPv4 Addresses (5.1.11) Hexadecimal Number System (5.2) Hexadecimal and IPv6 Addresses (5.2.1) Decimal to Hexadecimal Conversions (5.2.3) Hexadecimal to Decimal Conversion (5.2.4) Summary (5.3) Binary Number System Hexadecimal Number System Practice Check Your Understanding Questions Chapter 6 Data Link Layer Objectives Key Terms Introduction (6.0) Purpose of the Data Link Layer (6.1) The Data Link Layer (6.1.1) IEEE 802 LAN/MAN Data Link Sublayers (6.1.2) Providing Access to Media (6.1.3) Data Link Layer Standards (6.1.4) Topologies (6.2) Physical and Logical Topologies (6.2.1) WAN Topologies (6.2.2) Point-to-Point Hub and Spoke Mesh Point-to-Point WAN Topology (6.2.3) LAN Topologies (6.2.4) Legacy LAN Topologies Half-Duplex and Full-Duplex Communication (6.2.5) Half-Duplex Communication Full-Duplex Communication Access Control Methods (6.2.6) Contention-Based Access Controlled Access Contention-Based Access—CSMA/CD (6.2.7) Contention-Based Access—CSMA/CA (6.2.8) Data Link Frame (6.3) The Frame (6.3.1) Frame Fields (6.3.2) Layer 2 Addresses (6.3.3) LAN and WAN Frames (6.3.4) Summary (6.4) Purpose of the Data Link Layer Topologies Data Link Frame Practice Check Your Understanding Questions Chapter 7 Ethernet Switching Objectives Key Terms Introduction (7.0) Ethernet Frames (7.1) Ethernet Encapsulation (7.1.1) Data Link Sublayers (7.1.2) MAC Sublayer (7.1.3) Data Encapsulation Accessing the Media Ethernet Frame Fields (7.1.4) Ethernet MAC Address (7.2) MAC Address and Hexadecimal (7.2.1) Ethernet MAC Address (7.2.2) Frame Processing (7.2.3) Unicast MAC Address (7.2.4) Broadcast MAC Address (7.2.5) Multicast MAC Address (7.2.6) The MAC Address Table (7.3) Switch Fundamentals (7.3.1) Switch Learning and Forwarding (7.3.2) Examine the Source MAC Address Find the Destination MAC Address Filtering Frames (7.3.3) Switch Speeds and Forwarding Methods (7.4) Frame Forwarding Methods on Cisco Switches (7.4.1) Cut-Through Switching (7.4.2) Memory Buffering on Switches (7.4.3) Duplex and Speed Settings (7.4.4) Auto-MDIX (7.4.5) Summary (7.5) Ethernet Frame Ethernet MAC Address The MAC Address Table Switch Speeds and Forwarding Methods Practice Check Your Understanding Questions Chapter 8 Network Layer Objectives Key Terms Introduction (8.0) Network Layer Characteristics (8.1) The Network Layer (8.1.1) IP Encapsulation (8.1.2) Characteristics of IP (8.1.3) Connectionless (8.1.4) Best Effort (8.1.5) Media Independent (8.1.6) IPv4 Packet (8.2) IPv4 Packet Header (8.2.1) IPv4 Packet Header Fields (8.2.2) IPv6 Packet (8.3) Limitations of IPv4 (8.3.1) IPv6 Overview (8.3.2) IPv4 Packet Header Fields in the IPv6 Packet Header (8.3.3) IPv6 Packet Header (8.3.4) How a Host Routes (8.4) Host Forwarding Decision (8.4.1) Default Gateway (8.4.2) A Host Routes to the Default Gateway (8.4.3) Host Routing Tables (8.4.4) Introduction to Routing (8.5) Router Packet Forwarding Decision (8.5.1) IP Router Routing Table (8.5.2) Static Routing (8.5.3) Dynamic Routing (8.5.4) Introduction to an IPv4 Routing Table (8.5.6) Summary (8.6) Network Layer Characteristics IPv4 Packet IPv6 Packet How a Host Routes Introduction to Routing Practice Check Your Understanding Questions Chapter 9 Address Resolution Objectives Key Terms Introduction (9.0) MAC and IP (9.1) Destination on Same Network (9.1.1) Destination on Remote Network (9.1.2) ARP (9.2) ARP Overview (9.2.1) ARP Functions (9.2.2) Removing Entries from an ARP Table (9.2.6) ARP Tables on Networking Devices (9.2.7) ARP Issues—ARP Broadcasts and ARP Spoofing (9.2.8) IPv6 Neighbor Discovery (9.3) IPv6 Neighbor Discovery Messages (9.3.2) IPv6 Neighbor Discovery—Address Resolution (9.3.3) Summary (9.4) MAC and IP ARP Neighbor Discovery Practice Check Your Understanding Questions Chapter 10 Basic Router Configuration Objectives Introduction (10.0) Configure Initial Router Settings (10.1) Basic Router Configuration Steps (10.1.1) Basic Router Configuration Example (10.1.2) Configure Interfaces (10.2) Configure Router Interfaces (10.2.1) Configure Router Interfaces Example (10.2.2) Verify Interface Configuration (10.2.3) Configuration Verification Commands (10.2.4) Configure the Default Gateway (10.3) Default Gateway on a Host (10.3.1) Default Gateway on a Switch (10.3.2) Summary (10.4) Configure Initial Router Settings Configure Interfaces Configure the Default Gateway Practice Check Your Understanding Questions Chapter 11 IPv4 Addressing Objectives Key Terms Introduction (11.0) IPv4 Address Structure (11.1) Network and Host Portions (11.1.1) The Subnet Mask (11.1.2) The Prefix Length (11.1.3) Determining the Network: Logical AND (11.1.4) Network, Host, and Broadcast Addresses (11.1.6) Network Address Host Addresses Broadcast Address IPv4 Unicast, Broadcast, and Multicast (11.2) Unicast (11.2.1) Broadcast (11.2.2) IP Directed Broadcasts Multicast (11.2.3) Types of IPv4 Addresses (11.3) Public and Private IPv4 Addresses (11.3.1) Routing to the Internet (11.3.2) Special Use IPv4 Addresses (11.3.4) Loopback Addresses Link-Local Addresses Legacy Classful Addressing (11.3.5) Assignment of IP Addresses (11.3.6) Network Segmentation (11.4) Broadcast Domains and Segmentation (11.4.1) Problems with Large Broadcast Domains (11.4.2) Reasons for Segmenting Networks (11.4.3) Subnet an IPv4 Network (11.5) Subnet on an Octet Boundary (11.5.1) Subnet Within an Octet Boundary (11.5.2) Subnet a Slash 16 and a Slash 8 Prefix (11.6) Create Subnets with a Slash 16 Prefix (11.6.1) Create 100 Subnets with a Slash 16 Prefix (11.6.2) Create 1000 Subnets with a Slash 8 Prefix (11.6.3) Subnet to Meet Requirements (11.7) Subnet Private Versus Public IPv4 Address Space (11.7.1) What About the DMZ? Minimize Unused Host IPv4 Addresses and Maximize Subnets (11.7.2) Example: Efficient IPv4 Subnetting (11.7.3) VLSM (11.8) IPv4 Address Conservation (11.8.3) VLSM (11.8.4) VLSM Topology Address Assignment (11.8.5) Structured Design (11.9) IPv4 Network Address Planning (11.9.1) Device Address Assignment (11.9.2) Summary (11.10) IPv4 Addressing Structure IPv4 Unicast, Broadcast, and Multicast Types of IPv4 Addresses Network Segmentation Subnet an IPv4 Network Subnet a /16 and a /8 Prefix Subnet to Meet Requirements Variable-Length Subnet Masking Structured Design Practice Check Your Understanding Questions Chapter 12 IPv6 Addressing Objectives Key Terms Introduction (12.0) IPv4 Issues (12.1) Need for IPv6 (12.1.1) Internet of Things IPv4 and IPv6 Coexistence (12.1.2) Dual Stack Tunneling Translation IPv6 Address Representation (12.2) IPv6 Addressing Formats (12.2.1) Preferred Format Rule 1—Omit Leading Zeros (12.2.2) Rule 2—Double Colon (12.2.3) IPv6 Address Types (12.3) Unicast, Multicast, Anycast (12.3.1) IPv6 Prefix Length (12.3.2) Types of IPv6 Unicast Addresses (12.3.3) A Note About the Unique Local Address (12.3.4) IPv6 GUA (12.3.5) IPv6 GUA Structure (12.3.6) Global Routing Prefix Subnet ID Interface ID IPv6 LLA (12.3.7) GUA and LLA Static Configuration (12.4) Static GUA Configuration on a Router (12.4.1) Static GUA Configuration on a Windows Host (12.4.2) Static Configuration of a Link-Local Unicast Address (12.4.3) Dynamic Addressing for IPv6 GUAs (12.5) RS and RA Messages (12.5.1) Method 1: SLAAC (12.5.2) Method 2: SLAAC and Stateless DHCPv6 (12.5.3) Method 3: Stateful DHCPv6 (12.5.4) EUI-64 Process vs. Randomly Generated (12.5.5) EUI-64 Process (12.5.6) Randomly Generated Interface IDs (12.5.7) Dynamic Addressing for IPv6 LLAs (12.6) Dynamic LLAs (12.6.1) Dynamic LLAs on Windows (12.6.2) Dynamic LLAs on Cisco Routers (12.6.3) Verify IPv6 Address Configuration (12.6.4) IPv6 Multicast Addresses (12.7) Assigned IPv6 Multicast Addresses (12.7.1) Well-Known IPv6 Multicast Addresses (12.7.2) Solicited-Node IPv6 Multicast Addresses (12.7.3) Subnet an IPv6 Network (12.8) Subnet Using the Subnet ID (12.8.1) IPv6 Subnetting Example (12.8.2) IPv6 Subnet Allocation (12.8.3) Router Configured with IPv6 Subnets (12.8.4) Summary (12.9) IPv4 Issues IPv6 Address Representation IPv6 Address Types GUA and LLA Static Configuration Dynamic Addressing for IPv6 GUAs Dynamic Addressing for IPv6 LLAs IPv6 Multicast Addresses Subnet an IPv6 Network Practice Check Your Understanding Questions Chapter 13 ICMP Objectives Introduction (13.0) ICMP Messages (13.1) ICMPv4 and ICMPv6 Messages (13.1.1) Host Reachability (13.1.2) Destination or Service Unreachable (13.1.3) Time Exceeded (13.1.4) ICMPv6 Messages (13.1.5) Ping and Traceroute Tests (13.2) Ping—Test Connectivity (13.2.1) Ping the Loopback (13.2.2) Ping the Default Gateway (13.2.3) Ping a Remote Host (13.2.4) Traceroute—Test the Path (13.2.5) Round-Trip Time (RTT) IPv4 TTL and IPv6 Hop Limit Summary (13.3) ICMP Messages Ping and Traceroute Testing Practice Check Your Understanding Questions Chapter 14 Transport Layer Objectives Key Terms Introduction (14.0) Transportation of Data (14.1) Role of the Transport Layer (14.1.1) Transport Layer Responsibilities (14.1.2) Transport Layer Protocols (14.1.3) Transmission Control Protocol (TCP) (14.1.4) User Datagram Protocol (UDP) (14.1.5) The Right Transport Layer Protocol for the Right Application (14.1.6) TCP Overview (14.2) TCP Features (14.2.1) TCP Header (14.2.2) TCP Header Fields (14.2.3) Applications That Use TCP (14.2.4) UDP Overview (14.3) UDP Features (14.3.1) UDP Header (14.3.2) UDP Header Fields (14.3.3) Applications that use UDP (14.3.4) Port Numbers (14.4) Multiple Separate Communications (14.4.1) Socket Pairs (14.4.2) Port Number Groups (14.4.3) The netstat Command (14.4.4) TCP Communication Process (14.5) TCP Server Processes (14.5.1) TCP Connection Establishment (14.5.2) Session Termination (14.5.3) TCP Three-Way Handshake Analysis (14.5.4) Reliability and Flow Control (14.6) TCP Reliability—Guaranteed and Ordered Delivery (14.6.1) TCP Reliability—Data Loss and Retransmission (14.6.3) TCP Flow Control—Window Size and Acknowledgments (14.6.5) TCP Flow Control—Maximum Segment Size (MSS) (14.6.6) TCP Flow Control—Congestion Avoidance (14.6.7) UDP Communication (14.7) UDP Low Overhead Versus Reliability (14.7.1) UDP Datagram Reassembly (14.7.2) UDP Server Processes and Requests (14.7.3) UDP Client Processes (14.7.4) Summary (14.8) Transportation of Data TCP Overview UDP Overview Port Numbers TCP Communications Process Reliability and Flow Control UDP Communication Practice Check Your Understanding Questions Chapter 15 Application Layer Objectives Key Terms Introduction (15.0) Application, Presentation, and Session (15.1) Application Layer (15.1.1) Presentation and Session Layer (15.1.2) TCP/IP Application Layer Protocols (15.1.3) Peer-to-Peer (15.2) Client-Server Model (15.2.1) Peer-to-Peer Networks (15.2.2) Peer-to-Peer Applications (15.2.3) Common P2P Applications (15.2.4) Web and Email Protocols (15.3) Hypertext Transfer Protocol and Hypertext Markup Language (15.3.1) HTTP and HTTPS (15.3.2) Email Protocols (15.3.3) SMTP, POP, and IMAP (15.3.4) SMTP POP IMAP IP Addressing Services (15.4) Domain Name Service (15.4.1) DNS Message Format (15.4.2) DNS Hierarchy (15.4.3) The nslookup Command (15.4.4) Dynamic Host Configuration Protocol (15.4.6) DHCP Operation (15.4.7) File Sharing Services (15.5) File Transfer Protocol (15.5.1) Server Message Block (15.5.2) Summary Application, Presentation, and Session Peer-to-Peer Web and Email Protocols IP Addressing Services File Sharing Services Practice Check Your Understanding Questions Chapter 16 Network Security Fundamentals Objectives Key Terms Introduction (16.0) Security Threats and Vulnerabilities (16.1) Types of Threats (16.1.1) Types of Vulnerabilities (16.1.2) Physical Security (16.1.3) Network Attacks (16.2) Types of Malware (16.2.1) Viruses Worms Trojan Horses Reconnaissance Attacks (16.2.2) Access Attacks (16.2.3) Password Attacks Trust Exploitation Port Redirection Man-in-the-Middle Denial of Service Attacks (16.2.4) DoS Attack DDoS Attack Network Attack Mitigations (16.3) The Defense-in-Depth Approach (16.3.1) Keep Backups (16.3.2) Upgrade, Update, and Patch (16.3.3) Authentication, Authorization, and Accounting (16.3.4) Firewalls (16.3.5) Types of Firewalls (16.3.6) Endpoint Security (16.3.7) Device Security (16.4) Cisco AutoSecure (16.4.1) Passwords (16.4.2) Additional Password Security (16.4.3) Enable SSH (16.4.4) Disable Unused Services (16.4.5) Summary Security Threats and Vulnerabilities Network Attacks Network Attack Mitigation Device Security Practice Check Your Understanding Questions Chapter 17 Build a Small Network Objectives Key Terms Introduction (17.0) Devices in a Small Network (17.1) Small Network Topologies (17.1.1) Device Selection for a Small Network (17.1.2) Cost Speed and Types of Ports/Interfaces Expandability Operating System Features and Services IP Addressing for a Small Network (17.1.3) Redundancy in a Small Network (17.1.4) Traffic Management (17.1.5) Small Network Applications and Protocols (17.2) Common Applications (17.2.1) Network Applications Application Layer Services Common Protocols (17.2.2) Voice and Video Applications (17.2.3) Scale to Larger Networks (17.3) Small Network Growth (17.3.1) Protocol Analysis (17.3.2) Employee Network Utilization (17.3.3) Verify Connectivity (17.4) Verify Connectivity with Ping (17.4.1) Extended Ping (17.4.2) Verify Connectivity with Traceroute (17.4.3) Extended Traceroute (17.4.4) Network Baseline (17.4.5) Host and IOS Commands (17.5) IP Configuration on a Windows Host (17.5.1) IP Configuration on a Linux Host (17.5.2) IP Configuration on a macOS Host (17.5.3) The arp Command (17.5.4) Common show Commands Revisited (17.5.5) The show cdp neighbors Command (17.5.6) The show ip interface brief Command (17.5.7) Verify Switch Interfaces Troubleshooting Methodologies (17.6) Basic Troubleshooting Approaches (17.6.1) Resolve or Escalate? (17.6.2) The debug Command (17.6.3) The terminal monitor Command (17.6.4) Troubleshooting Scenarios (17.7) Duplex Operation and Mismatch Issues (17.7.1) IP Addressing Issues on IOS Devices (17.7.2) IP Addressing Issues on End Devices (17.7.3) Default Gateway Issues (17.7.4) Troubleshooting DNS Issues (17.7.5) Summary (17.8) Devices in a Small Network Small Network Applications and Protocols Scale to Larger Networks Verify Connectivity Host and IOS Commands Troubleshooting Methodologies Troubleshooting Scenarios Practice Check Your Understanding Questions Appendix A Answers to “Check Your Understanding” Questions Key Terms Glossary Index Command Syntax Conventions The conventions used to present command syntax in this book are the same conventions used in the IOS Command Reference. The Command Reference describes these conventions as follows: Boldface indicates commands and keywords that are entered literally as shown. In actual configuration examples and output (not general command syntax), boldface indicates commands that are manually input by the user (such as a show command). Italic indicates arguments for which you supply actual values. Vertical bars ( | ) separate alternative, mutually exclusive elements. Square brackets ([ ]) indicate an optional element. Braces ({ }) indicate a required choice. Braces within brackets ([{ }]) indicate a required choice within an optional element. Introduction Introduction to Networks Companion Guide (CCNAv7) is the official supplemental textbook for the Cisco Network Academy CCNA Introduction to Networks Version 7 course. Cisco Networking Academy is a comprehensive program that delivers information technology skills to students around the world. The curriculum emphasizes real-world practical application and provides opportunities to gain the skills and hands- on experience needed to design, install, operate, and maintain networks in small business, medium-sized business as well as enterprise and service provider environments. This book provides a ready reference that explains the same networking concepts, technologies, protocols, and devices as the online curriculum. This book emphasizes key topics, terms, and activities and provides some alternative explanations and examples to supplement the course. You can use the online curriculum as directed by your instructor and then use this Companion Guide’s study tools to help solidify your understanding of all the topics. WHO SHOULD READ THIS BOOK The book, like the course it accompanies, is designed as an introduction to data network technology for those pursuing careers as network professionals as well as those who need an introduction to network technology for professional growth. Topics are presented concisely, starting with the most fundamental concepts and progressing to a comprehensive understanding of network communication. The content of this text provides the foundation for additional Cisco Networking Academy courses and preparation for the CCNA certification. BOOK FEATURES The educational features of this book focus on supporting topic coverage, readability, and practice of the course material to facilitate your full understanding of the course material. Topic Coverage The following list gives you a thorough overview of the features provided in each chapter so that you can make constructive use of your study time: Objectives: Listed at the beginning of each chapter, the objectives reference the core concepts covered in the chapter. The objectives match the objectives stated in the corresponding chapters of the online curriculum; however, the question format in the Companion Guide encourages you to think about finding the answers as you read the chapter. Notes: These are short sidebars that point out interesting facts, timesaving methods, and important safety issues. Summary: At the end of each chapter is a summary of the chapter’s key concepts. It provides a synopsis of the chapter and serves as a study aid. Practice: At the end of chapter is a full list of all the labs, class activities, and Packet Tracer activities to refer to at study time. Readability The following features are provided to help you understand networking vocabulary: Key terms: Each chapter begins with a list of key terms, along with a page-number reference to find the term used inside the chapter. The terms are listed in the order in which they are explained in the chapter. This handy reference allows you to find a term, flip to the page where the term appears, and see the term used in context. The Key Terms Glossary defines all the key terms. Key Terms Glossary: This book contains an all-new Key Terms Glossary that defines more than 1000 terms. Practice Practice makes perfect. This Companion Guide offers you ample opportunities to put what you learn into practice. You will find the following features valuable and effective in reinforcing the instruction that you receive: Check Your Understanding questions and answer key: Review questions are presented at the end of each chapter as a self- assessment tool. These questions match the style of questions in the online course. Appendix A, “Answers to ‘Check Your Understanding’ Questions,” provides an answer key to all the questions and includes an explanation of each answer. Labs and activities: Throughout each chapter, you are directed back to the online course to take advantage of the activities provided to reinforce concepts. In addition, at the end of each chapter is a “Practice” section that lists all the labs and activities to provide practice with the topics introduced in this chapter. Page references to online course: After most headings is a number in parentheses—for example, (1.1.2). This number refers to the page number in the online course so that you can easily jump to that spot online to view a video, practice an activity, perform a lab, or review a topic. About Packet Tracer Software and Activities Interspersed throughout the chapters, you’ll find a few Cisco Packet Tracer activities. Packet Tracer allows you to create networks, visualize how packets flow in a network, and use basic testing tools to determine whether a network would work. When you see this icon, you can use Packet Tracer with the listed file to perform a task suggested in this book. The activity files are available in the online course. Packet Tracer software is available only through the Cisco Networking Academy website. Ask your instructor for access to Packet Tracer. HOW THIS BOOK IS ORGANIZED This book corresponds closely to the Cisco Networking Academy CCNA IT Essential v7 course and is divided into 17 chapters, one appendix, and a glossary of key terms: Chapter 1, “Networking Today”: This chapter introduces the concept of a network and provides an overview of the different types of networks encountered. It examines how networks impact the way we work, learn, and play. This chapter also examines recent trends in networks, such as video, cloud computing, and BYOD and how to help ensure robust, reliable, secure networks to support these trends. Chapter 2, “Basic Switch and End Device Configuration”: This chapter introduces the operating system used with most Cisco devices: Cisco IOS. The basic purpose and functions of IOS are described, as are methods to access IOS. The chapter also describes how to maneuver through the IOS command-line interface as well as basic IOS device configuration. Chapter 3, “Protocols and Models”: This chapter examines the importance of rules or protocols for network communication. It explores the OSI reference model and the TCP/IP communication suite and examines how these models provide the necessary protocols to allow communication to occur on a modern converged network. Chapter 4, “Physical Layer”: This chapter introduces the lowest layer of the OSI model: the physical layer. This chapter explains the transmission of bits over the physical medium. Chapter 5, “Number Systems”: This chapter explains how to convert between decimal, binary, and hexadecimal number systems. Understanding these number systems is essential to understanding IPv4, IPv6, and Ethernet MAC addressing. Chapter 6, “Data Link Layer”: This chapter discusses how the data link layer prepares network layer packets for transmission, controls access to the physical media, and transports data across various media. This chapter includes a description of the encapsulation protocols and processes that occur as data travels across the LAN and the WAN. Chapter 7, “Ethernet Switching”: This chapter examines the functionality of the Ethernet LAN protocols. It explores how Ethernet functions, including how devices use Ethernet MAC addresses to communicate in a multiaccess network. The chapter discusses how Ethernet switches build MAC address tables and forward Ethernet frames. Chapter 8, “Network Layer”: This chapter introduces the function of the network layer—routing—and the basic device that performs this function—the router. It presents important routing concepts related to addressing, path determination, and data packets for both IPv4 and IPv6. The chapter also introduces how routers perform packet forwarding, static and dynamic routing, and the IP routing table. Chapter 9, “Address Resolution”: This chapter discusses how host computers and other end devices determine the Ethernet MAC address for a known IPv4 or IPv6 address. This chapter examines the ARP protocol for IPv4 address resolution and the Neighbor Discovery Protocol for IPv6. Chapter 10, “Basic Router Configuration”: This chapter explains how to configure a Cisco router, including IPv4 and IPv6 addressing on an interface. Chapter 11, “IPv4 Addressing”: This chapter focuses on IPv4 network addressing, including the types of addresses and address assignment. It describes how to use subnet masks to determine the number of subnetworks and hosts in a network. It examines how to improve network performance by optimally dividing the IPv4 address space based on network requirements. It explores the calculation of valid host addresses and the determination of both subnet and broadcast addresses. Chapter 12, “IPv6 Addressing”: This chapter focuses on IPv6 network addressing, including IPv6 address representation, types of addresses, and the structure of different types of IPv6 address. The chapter introduces the different methods that an end device can receive an IPv6 address automatically. Chapter 13, “ICMP”: This chapter introduces Internet Control Message Protocol (ICMP) tools, such as ping and trace. Chapter 14, “Transport Layer”: This chapter introduces Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) and examines how each of these protocols transports information across the network. It explores how TCP uses segmentation, the three-way handshake, and expectational acknowledg ments to ensure reliable delivery of data. It also examines the best-effort delivery mechanism provided by UDP and describes when its use would be preferred over the use of TCP. Chapter 15, “Application Layer”: This chapter introduces some protocols of the TCP/IP application layer, which also relates to the top three layers of the OSI model. The chapter focuses on the role of the application layer and how the applications, services, and protocols in the application layer make robust communication across data networks possible. This will be demonstrated by examining some key protocols and services, including HTTP, HTTPS, DNS, DHCP, SMTP/POP, and FTP. Chapter 16, “Network Security Fundamentals”: This chapter introduces network security threats and vulnerabilities. Various network attacks and mitigation techniques are discussed, along with how to secure network devices. Chapter 17, “Build a Small Network”: This chapter reexamines the various components in a small network and describes how they work together to allow network growth. It examines network configuration and troubleshooting issues, along with different troubleshooting methodologies. Appendix A, “Answers to ‘Check Your Understanding’ Questions”: This appendix lists the answers to the “Check Your Understanding” review questions that are included at the end of each chapter. Key Terms Glossary: The Key Terms Glossary provides definitions for all the key terms identified in each chapter. Figure Credits Figure 2-2, screen shot of Windows 10 GUI © Microsoft 2020 Figure 2-4, screen shot of PuTTY © 1997-2020 Simon Tatham Figure 2-5, screen shot of Tera Term © 2004-2019 TeraTerm Project Figure 2-6, screen shot of SecureCRT © 1995-2020 VanDyke Software, Inc. Figure 2-9, screen shot of PuTTY startup screen © 1997- 2020 Simon Tatham Figure 2-10, screen shot of setting PuTTY to log a session to a text file © 1997-2020 Simon Tatham Figure 2-11, screen shot of turn off session logging © 1997-2020 Simon Tatham Figure 2-12, screen shot of configuring or verifying IPv4 addressing on a Windows host © Microsoft 2020 Figure 2-13, screen shot of configuring or verifying IPv6 addressing on a Windows host © Microsoft 2020 Figure 2-15, screen shot of accessing IPv4 properties on a Windows host © Microsoft 2020 Figure 2-16, screen shot of manually configuring IPv4 addressing on a Windows host © Microsoft 2020 Figure 2-17, screen shot of setting a Windows host to obtain IPv4 addressing automatically © Microsoft 2020 Figure 3-21A, © 2020 IEEE Figure 3-21B, © Internet Engineering Task Force Figure 3-21C, © Internet Assigned Numbers Authority Figure 3-21D, © 2020 Internet Corporation for Assigned Names and Numbers Figure 3-21E, © ITU 2020 Figure 3-21F, © Telecommunications Industry Association Figure 3-22A, © 2020 Internet Society Figure 3-22B, © Internet Engineering Task Force Figure 3-22C, © Internet Engineering Task Force Figure 3-22D, © Internet Research Task Force Figure 11-2, screen shot of IPv4 addressing on a Windows PC © Microsoft 2020 Figure 11-13A, © 1997–2020, American Registry for Internet Numbers Figure 11-13B, © 1992-2020 the Réseaux IP Européens Network Coordination Centre RIPE NCC Figure 11-13C, © Latin America and Caribbean Network Information Centre Figure 11-13D, © 2020 African Network Information Centre (AFRINIC) Figure 11-13E, © 2020 APNIC Figure 12-1A, © 1997–2020, American Registry for Internet Numbers Figure 12-1B, © 1992-2020 the Réseaux IP Européens Network Coordination Centre RIPE NCC Figure 12-1C, © Latin America and Caribbean Network Information Centre Figure 12-1D, © 2020. All Rights Reserved - African Network Information Centre (AFRINIC) Figure 12-1E, © 2020 APNIC Figure 12-13, screen shot of Manually Configuring IPv6 Addressing on a Windows Host © Microsoft 2020 Figure 16-8, screen shot of Windows 10 Update © Microsoft 2020 Figure 17-6, screen shot of Windows Task Manager © Microsoft 2020 Figure 17-8, screen shot of Wireshark capture showing packet statistics © Microsoft 2020 Figure 17-9, screen shot of Windows 10 usage details for a Wi-Fi network connection © Microsoft 2020 Figure 17-17, screen shot of Windows 10 network connection details © Microsoft 2020 Figure 17-18, screen shot of Linux Ubuntu connection information © Canonical Ltd Figure 17-19, screen shot of configuration information on a macOS host © Microsoft 2020 Chapter 1 Networking Today OBJECTIVES Upon completion of this chapter, you will be able to answer the following questions: How do networks affect our daily lives? How are host and network devices used? What are network representations, and how are they used in network topologies? What are the characteristics of common types of networks? How do LANs and WANs interconnect to the internet? What are the four basic requirements of a reliable network? How do trends such as BYOD, online collaboration, video, and cloud computing change the way we interact? What are some basic security threats and solutions for all networks? What employment opportunities are available in the networking field? KEY TERMS This chapter uses the following key terms. You can find the definitions in the glossary at the end of the book. server page 4 client page 4 end device page 6 intermediary device page 6 topology page 10 small office and home office (SOHO) networks page 12 local-area networks (LANs) page 13 wide-area networks (WANs) page 13 internet page 15 intranet page 16 extranet page 16 internet service provider (ISP) page 17 digital subscriber line (DSL) page 18 cellular connection page 18 satellite connection page 19 dialup telephone connection page 19 converged data network page 21 fault-tolerant network page 24 scalable network page 24 quality of service (QoS) page 25 confidentiality page 27 integrity page 27 availability page 27 bring your own device (BYOD) page 28 cloud computing page 29 powerline networking page 31 wireless internet service provider (WISP) page 32 INTRODUCTION (1.0) Congratulations! This chapter starts you on your path to a successful career in information technology by giving you a foundational understanding of the creation, operation, and maintenance of networks. As a bonus, you get to dive into networking simulations using Packet Tracer. We promise you will really enjoy it! NETWORKS AFFECT OUR LIVES (1.1) Networks are all around us. They provide us with a way to communicate and share information and resources with individuals in the same location or around the world. Networks require an extensive array of technologies and procedures that can readily adapt to varying conditions and requirements. Networks Connect Us (1.1.1) Among all of the essentials for human existence, the need to interact with others ranks just below our need to sustain life. Communication is almost as important to us as our reliance on air, water, food, and shelter. In today’s world, through the use of networks, we are connected as never before. People with ideas can communicate instantly with others to make those ideas reality. News events and discoveries are known worldwide in seconds. Individuals can even connect and play games with friends physically separated by oceans and continents. Video—The Cisco Networking Academy Learning Experience (1.1.2) World changers aren’t born. They are made. Since 1997 Cisco Networking Academy has been working toward a single goal: educating and building the skills of the next generation of talent required for the digital economy. Refer to the online course to view this video. No Boundaries (1.1.3) Advancements in networking technologies are perhaps the most significant changes in the world today. They are helping to create a world in which national borders, geographic distances, and physical limitations become less relevant and present ever-diminishing obstacles. The internet has changed the manner in which our social, commercial, political, and personal interactions occur. The immediate nature of communications over the internet encourages the creation of global communities. Global communities allow for social interaction that is independent of location or time zone. The creation of online communities for the exchange of ideas and information has the potential to increase productivity opportunities around the globe. The cloud lets us store documents and pictures and access them anywhere, anytime. So whether we are on a train, in a park, or standing on top of a mountain, we can seamlessly access our cloud-stored data and applications on any device. NETWORK COMPONENTS (1.2) Many different components are required to enable a network to provide services and resources. These various components work together to ensure that resources are delivered in an efficient manner to those requiring the services. Host Roles (1.2.1) If you want to be part of a global online community, your computer, tablet, or smartphone must first be connected to a network. That network must be connected to the internet. This section discusses the parts of a network. See if you recognize these components in your own home or school network! Any computer that is connected to a network and that participates directly in network communication is classified as a host. Hosts can be called end devices. Some hosts are also called clients. However, the term host specifically refers to a device on a network that is assigned a number for communication purposes. This number, which identifies the host within the particular network, is called the Internet Protocol (IP) address. An IP address identifies the host and the network to which the host is attached. Servers are computers with software that allows them to provide information, such as email or web pages, to other end devices on the network. Each service requires separate server software. For example, a server requires web server software in order to provide web services to the network. A computer with server software can simultaneously provide services to many different clients. As mentioned earlier, a client is a type of host. Clients have software for requesting and displaying the information obtained from the server, as shown in Figure 1-1. Figure 1-1 A Client and a Server An example of client software is a web browser, such as Chrome or Firefox. A single computer can also run multiple types of client software. For example, a user can check email and view a web page while instant messaging and listening to an audio stream. Table 1-1 lists three common types of server software. Table 1-1 Common Server Software Soft Description ware Type Em An email server runs email server software. Clients use mail ail client software, such as Microsoft Outlook, to access email on the server. We A web server runs web server software. Clients use browser b software, such as Windows Internet Explorer, to access web pages on the server. File A file server stores corporate and user files in a central location. The client devices access these files with client software such as Windows File Explorer. Peer-to-Peer (1.2.2) Client and server software usually run on separate computers, but it is also possible for one computer to be used for both roles at the same time. In small businesses and homes, many computers function as both servers and clients on the network. This type of network, called a peer-to-peer network, is shown in Figure 1-2. Figure 1-2 Peer-to-Peer Network Table 1-2 outlines the advantages and disadvantages of peer-to-peer networking. Table 1-2 Peer-to-Peer Networking Advantages and Disadvantages Advantages Disadvantages Easy to set up No centralized administration Less complex Not as secure Lower cost because network Not scalable devices and dedicated servers may not be required Can be used for simple tasks All devices may act as both clients such as transferring files and and servers, which can slow their sharing printers performance End Devices (1.2.3) The network devices that people are most familiar with are end devices. To distinguish one end device from another, each end device on a network has an address. When an end device initiates communication, it uses the address of the destination end device to specify where to deliver the message. An end device is either the source or destination of a message transmitted over the network, as shown in Figure 1-3. Figure 1-3 Data Flow Through a Network Intermediary Devices (1.2.4) Intermediary devices connect individual end devices to a network. They can connect multiple individual networks to form an internetwork. These intermediary devices provide connectivity and ensure that data flows across the network. Intermediary devices use the destination end device address, in conjunction with information about the network interconnections, to determine the path that messages should take through the network. Figure 1-4 shows examples of the most common intermediary devices. Figure 1-4 Intermediary Devices Intermediary network devices perform some or all of these functions: Regenerate and retransmit communication signals Maintain information about what pathways exist through the network and internetwork Notify other devices about errors and communication failures Direct data along alternate pathways when there is a link failure Classify and direct messages according to priorities Permit or deny the flow of data, based on security settings Note Figure 1-4 does not show any legacy Ethernet hubs. An Ethernet hub is also known as a multiport repeater. Repeaters regenerate and retransmit communication signals. Notice that every intermediary device performs the function of a repeater. Network Media (1.2.5) Communication transmits across a network on media. The media provide the channel over which a message travels from source to destination. Modern networks primarily use three types of media to interconnect devices, as shown in Figure 1-5: Metal wires within cables: Data is encoded into electrical impulses. Glass or plastic fibers within cables (fiber-optic cable): Data is encoded into pulses of light. Wireless transmission: Data is encoded via modulation of specific frequencies of electromagnetic waves. Figure 1-5 Network Media Different types of network media have different features and benefits. Not all network media have the same characteristics, and they are not all appropriate for the same purpose. Check Your Understanding—Network Components (1.2.6) Refer to the online course to complete this activity. NETWORK REPRESENTATIONS AND TOPOLOGIES (1.3) A network’s infrastructure is documented using commonly used symbols to represent devices and different types of diagrams to represent the interconnection of these devices in the network. Understanding these symbols and diagrams is an important aspect of understanding network communications. Network Representations (1.3.1) Network architects and administrators must be able to show what their networks look like. They need to be able to easily see which components connect to other components, where they are located, and how they are connected. Diagrams of networks often use symbols, like those shown in Figure 1-6, to represent the different devices and connections in a network. Figure 1-6 Network Symbols for Topology Diagrams A diagram provides an easy way to understand how devices connect in a network. This type of “picture” of a network is known as a topology diagram. The ability to recognize the logical representations of the physical networking components is critical to being able to visualize the organization and operation of a network. In addition to these representations, specialized terminology is used to describe how each of these devices and media connect to each other: Network interface card (NIC): A NIC physically connects an end device to a network. Physical port: A port is a connector or an outlet on a networking device where a medium connects to an end device or another networking device. Interface: An interface is a specialized port on a networking device that connects to a network. Because routers connect networks, the ports on a router are referred to as network interfaces. Note Often, the terms port and interface are used interchangeably. Topology Diagrams (1.3.2) Topology diagrams are mandatory documentation for anyone working with a network. Such a diagram provides a visual map of how the network is connected. There are two types of topology diagrams: physical and logical. Physical Topology Diagrams A physical topology diagram illustrates the physical locations of intermediary devices and cable installation, as shown in Figure 1-7. You can see that the rooms in which these devices are located are labeled in this physical topology. Figure 1-7 Physical Topology Example Logical Topology Diagrams A logical topology diagram illustrates devices, ports, and the addressing scheme of a network, as shown in Figure 1-8. You can see which end devices are connected to which intermediary devices and what media are being used. Figure 1-8 Logical Topology Example The topologies shown in physical and logical diagrams are appropriate for your level of understanding at this point in the course. Search the internet for “network topology diagrams” to see some more complex examples. If you add the word “Cisco” to your search phrase, you will find many topologies using icons that are similar to what you have seen in these figures. Check Your Understanding—Network Representations and Topologies (1.3.3) Refer to the online course to complete this activity. COMMON TYPES OF NETWORKS (1.4) Networks can be categorized in various ways, including by size, by location, or by function. No matter the type of network being discussed, the underlying principles apply to all types of networks. Networks of Many Sizes (1.4.1) Now that you are familiar with the components that make up networks and their representations in physical and logical topologies, you are ready to learn about the many different types of networks. Networks come in all sizes. They range from simple networks consisting of two computers to networks connecting millions of devices. Simple home networks let you share resources, such as printers, documents, pictures, and music, among a few local end devices. Small office and home office (SOHO) networks allow people to work from home or a remote office. Many self- employed workers use these types of networks to advertise and sell products, order supplies, and communicate with customers. Businesses and large organizations use networks to provide consolidation, storage, and access to information on network servers. Networks provide email, instant messaging, and collaboration among employees. Many organizations use a network connection to the internet to provide products and services to customers. The internet is the largest network in existence. In fact, the term internet means a “network of networks.” The internet is a collection of interconnected private and public networks. In small businesses and homes, many computers function as both servers and clients on the network. This type of network is called a peer-to-peer network. There are networks of varying sizes that can be categorized in various ways, including the following: Small home networks: Small home networks connect a few computers to each other and to the internet. SOHO networks: A SOHO network allows computers in a home office or a remote office to connect to a corporate network or access centralized, shared resources. Medium to large networks: Medium to large networks, such as those used by corporations and schools, can have many locations with hundreds or thousands of interconnected hosts. Worldwide networks: The internet is a network of networks that connects hundreds of millions of computers worldwide. LANs and WANs (1.4.2) Network infrastructures vary greatly in terms of Size of the area covered Number of users connected Number and types of services available Area of responsibility The two most common types of network infrastructures are local-area networks (LANs) and wide-area networks (WANs). A LAN is a network infrastructure that provides access to users and end devices in a small geographic area. A LAN is typically used in a department within an enterprise, a home, or a small business network. A WAN is a network infrastructure that provides access to other networks over a wide geographic area, which is typically owned and managed by a larger corporation or a telecommunications service provider. Figure 1-9 shows LANs connected to a WAN. Figure 1-9 Example of Connected LANs and WANs LANs A LAN is a network infrastructure that spans a small geographic area. LANs have specific characteristics: LANs interconnect end devices in a limited area such as a home, school, office building, or campus. A LAN is usually administered by a single organization or individual. Administrative control is enforced at the network level and governs the security and access control policies. LANs provide high-speed bandwidth to internal end devices and intermediary devices, as shown Figure 1-10. Figure 1-10 Example of a LAN WANs Figure 1-11 shows a WAN that interconnects two LANs. A WAN is a network infrastructure that spans a wide geographic area. WANs are typically managed by service providers (SPs) or internet service providers (ISPs). Figure 1-11 Example of a WAN Link WANs have specific characteristics: WANs interconnect LANs over wide geographic areas such as between cities, states, provinces, countries, or continents. WANs are usually administered by multiple service providers. WANs typically provide slower-speed links between LANs. The Internet (1.4.3) The internet is a worldwide collection of interconnected networks (internetworks, or internet for short). Figure 1- 12 shows one way to view the internet as a collection of interconnected LANs and WANs. Figure 1-12 Example of a View of the Internet Some of the LAN examples in Figure 1-12 are connected to each other through a WAN connection. WANs are then connected to each other. The WAN connection lines (which look like lightning bolts) represent the varieties of ways we connect networks. WANs can connect through copper wires, fiber-optic cables, and wireless transmissions (not shown). The internet is not owned by any individual or group. Ensuring effective communication across this diverse infrastructure requires the application of consistent and commonly recognized technologies and standards as well as the cooperation of many network administration agencies. Organizations have been developed to help maintain the structure and standardization of internet protocols and processes. These organizations include the Internet Engineering Task Force (IETF), Internet Corporation for Assigned Names and Numbers (ICANN), and the Internet Architecture Board (IAB), among many others. Intranets and Extranets (1.4.4) Two other terms are similar to the term internet: intranet and extranet. The term intranet is often used to refer to a private connection of LANs and WANs that belongs to an organization. An intranet is designed to be accessible only by the organization’s members, employees, or others with authorization. An organization may use an extranet to provide secure and safe access to individuals who work for a different organization but require access to the organization’s data. Here are some examples of extranets: A company that is providing access to outside suppliers and contractors A hospital that is providing a booking system to doctors so they can make appointments for their patients A local education office that is providing budget and personnel information to the schools in its district Figure 1-13 illustrates the levels of access that different groups have to a company intranet, a company extranet, and the internet. Figure 1-13 Levels of Access from Intranet to Internet Check Your Understanding—Common Types of Networks (1.4.5) Refer to the online course to complete this activity. INTERNET CONNECTIONS (1.5) End devices such as computers and smartphones connect to a network in a variety of ways, using both wired and wireless means. These same types of connections are used to interconnect intermediary devices. Internet Access Technologies (1.5.1) Now you have a basic understanding of what makes up a network and the different types of networks. How do you actually connect users and organizations to the internet? As you may already know, there are many different ways to do this. Home users, remote workers, and small offices typically require a connection to an internet service provider (ISP) to access the internet. Connection options vary greatly between ISPs and in different geographic locations. However, popular choices include broadband cable, broadband digital subscriber line (DSL), wireless WANs, and mobile services. Organizations usually need access to other corporate sites as well as the internet. Fast connections are required to support business services such as IP phones, video conferencing, and data center storage. ISPs offer business-class interconnections. Popular business-class services include business DSL, leased lines, and Metro Ethernet. Home and Small Office Internet Connections (1.5.2) Figure 1-14 illustrates common connection options for small office and home office users: Figure 1-14 Small Office and Home Office Connection Options Cable connection: With this type of connection, typically offered by cable television service providers, the internet data signal transmits on the same cable that delivers cable television. This connection type provides a high-bandwidth, high-availability, and an always-on connection to the internet. Digital subscriber line (DSL): DSL provides high bandwidth, high availability, and an always-on connection to the internet. DSL runs over a telephone line. In general, small office and home office users connect using asymmetrical DSL (ADSL), which means that the download speed is faster than the upload speed. Cellular connection: Cellular internet access uses a cellphone network to connect. Wherever you can get a cellular signal, you can get cellular internet access. Performance is limited by the capabilities of the phone or other device and the cell tower to which it is connected. Satellite connection: The availability of satellite internet access is a benefit in areas that would otherwise have no internet connectivity at all. A satellite dish must have a clear line of sight to the satellite. Dialup telephone connection: This is an inexpensive option that uses any phone line and a modem. The low bandwidth provided by a dialup modem connection is not sufficient for large data transfers, although it is useful for mobile access while traveling. The choice of connection varies depending on geographic location and service provider availability. Businesses Internet Connections (1.5.3) Corporate connection options differ from home user options. Businesses may require higher bandwidth, dedicated bandwidth, and managed services. Connection options that are available differ depending on the type of service providers located nearby. Figure 1-15 illustrates common connection options for businesses: Figure 1-15 Business Connection Options Dedicated leased lines: Leased lines are reserved circuits within a service provider’s network that connect geographically separated offices for private voice and/or data networking. The circuits are rented at a monthly or yearly rate. Metro Ethernet: This is sometimes known as Ethernet WAN. In this chapter, we will refer to it as Metro Ethernet. Metro Ethernet can be used to extend LAN access technology into the WAN. Ethernet is a LAN technology you will learn about in a later chapter. Business DSL: Business DSL is available in various formats. A popular choice is symmetric DSL (SDSL), which is similar to the consumer version of DSL but provides uploads and downloads at the same high speeds. Satellite: Satellite service can provide a connection when a wired solution is not available. The choice of connection varies depending on geographic location and service provider availability. The Converging Network (1.5.4) Consider a school built 30 years ago. Back then, some classrooms were cabled for the data network, telephone network, and video network for televisions. These separate networks could not communicate with each other. Each network used different technologies to carry communication signals. Each network had its own set of rules and standards to ensure successful communication. Multiple services ran on multiple networks, as shown in Figure 1-16. Figure 1-16 Traditional Networks Today, separate data, telephone, and video networks have converged. Unlike dedicated networks, converged networks are capable of delivering data, voice, and video between many different types of devices over the same network infrastructure. This network infrastructure uses the same set of rules, agreements, and implementation standards. Converged data networks carry multiple services on one network, as shown in Figure 1-17. Figure 1-17 Converged Network Video—Download and Install Packet Tracer (1.5.5) This video shows you how to download and install Packet Tracer, which you can use to simulate the creation and testing of networks on your computer. Packet Tracer is a fun, take-home, flexible software program that will give you the opportunity to use the network representations and theories that you have just learned to build network models and explore relatively complex LANs and WANs. Students commonly use Packet Tracer to Prepare for a certification exam Practice what they learn in networking courses Sharpen their skills for a job interview Examine the impact of adding new technologies into existing network designs Build their skills for jobs in the Internet of Things Compete in global design challenges (such as at the 2017 PT 7 Design Challenge on Facebook) Packet Tracer is an essential learning tool used in many Cisco Networking Academy courses. To obtain and install a copy of Cisco Packet Tracer, follow these steps: Step 1. Log in to your Cisco Networking Academy “I’m Learning” page. Step 2. Select Resources. Step 3. Select Download Packet Tracer. Step 4. Select the version of Packet Tracer you require. Step 5. Save the file to your computer. Step 6. Launch the Packet Tracer installation program. Refer to the online course to view this video. Video—Getting Started in Cisco Packet Tracer (1.5.6) Packet Tracer is a tool that allows you to simulate real networks. It provides three main features: You can add devices and connect them via cables or wirelessly You can select, delete, inspect, label, and group components within a network You can manage a network by opening an existing/sample network, saving your current network, and modifying your user profile or preferences If you have used any program such as a word processor or spreadsheet, you are already familiar with the File menu commands located in the top menu bar. The Open, Save, Save As, and Exit commands work as they would for any program, but there are two commands that are special to Packet Tracer: The Open Samples command displays a directory of prebuilt examples of features and configurations for various network and Internet of Things devices included within Packet Tracer. The Exit and Logout command removes the registration information for this copy of Packet Tracer and requires the next user of this copy of Packet Tracer to go through the login procedure again. Refer to the online course to view this video. Packet Tracer—Network Representation (1.5.7) In this activity, you will explore how Packet Tracer serves as a modeling tool for network representations. RELIABLE NETWORKS (1.6) A network is a platform for distributing a wide range of services to end users in a reliable, efficient, and secure manner. Network Architecture (1.6.1) Have you ever been busy working online only to have “the internet go down”? As you know by now, the internet did not go down, but it is possible to lose your connection to it—and that can be very frustrating. With so many people in the world relying on network access to work and learn, it is imperative that networks be reliable. In this context, reliability means more than your connection to the internet. This section focuses on the four aspects of network reliability. The role of networks has changed. What was once a data- only network is now a system that enables connections between people, devices, and information in a media- rich, converged network environment. For networks to function efficiently and grow in this type of environment, networks must be built on a standard network architecture. Networks also support a wide range of applications and services. They must operate over the many different types of cables and devices that make up the physical infrastructure. The term network architecture, in this context, refers to the technologies that support the infrastructure and the programmed services and rules, or protocols, that move data across the network. As networks evolve, there are four basic characteristics that network architects must address to meet user expectations: Fault tolerance Scalability Quality of service (QoS) Security Fault Tolerance (1.6.2) A fault-tolerant network is a network that limits the number of devices affected by a failure. It is built to allow quick recovery when a failure occurs. These networks depend on multiple paths between the source and destination of a message. If one path fails, the messages are instantly sent over a different link. Having multiple paths to a destination is known as redundancy. Implementing a packet-switched network is one way to provide redundancy. Packet switching splits traffic into packets that are routed over a shared network. A single message, such as an email or a video stream, is broken into multiple message blocks, called packets. Each packet has the necessary addressing information of the source and destination of the message. The routers within the network switch the packets based on the condition of the network at that moment. This means that all the packets in a single message could take very different paths to the same destination. In Figure 1-18, the user is unaware and unaffected by the router that is dynamically changing the route when a link fails. Figure 1-18 Fault-Tolerant Design Scalability (1.6.3) A scalable network expands quickly to support new users and applications. It does this without degrading the performance of services that are being accessed by existing users. Figure 1-19 shows how a new network is easily added to an existing network. These networks are scalable because the designers have followed accepted standards and protocols. Because of these standards and protocols, software and hardware vendors can focus on improving products and services without having to design a new set of rules for operating within the network. Figure 1-19 Scalable Design Quality of Service (1.6.4) Quality of service (QoS) is an increasing requirement in networks today. New applications available to users over networks, such as voice and live video transmissions, create higher expectations for the quality of the delivered services. Have you ever tried to watch a video and experienced constant breaks and pauses? As data, voice, and video content continue to converge onto the same network, QoS becomes a primary mechanism for managing congestion and ensuring reliable delivery of content to all users. Congestion occurs when the demand for bandwidth exceeds the amount available. Network bandwidth is measured in the number of bits that can be transmitted in a single second, or bits per second (bps). When simultaneous communications are attempted across a network, the demand for network bandwidth can exceed its availability, creating network congestion. When the volume of traffic is greater than what can be transported across the network, devices hold the packets in memory until resources become available to transmit them. In Figure 1-20, one user is requesting a web page, and another is on a phone call. With a QoS policy in place, the router can manage the flow of data and voice traffic and give priority to voice communication if the network experiences congestion. Figure 1-20 QoS Design Network Security (1.6.5) The network infrastructure, the services, and the data contained on network-attached devices are crucial personal and business assets. Network administrators must address two types of network security concerns: network infrastructure security and information security. Securing the network infrastructure involves physically securing devices that provide network connectivity and preventing unauthorized access to the management software that resides on them, as shown in Figure 1-21. Figure 1-21 Security Design Network administrators must also protect the information contained within the packets being transmitted over the network, as well as the information stored on network-attached devices. In order to achieve the goals of network security, there are three primary requirements: Confidentiality: Data confidentiality means that only the intended and authorized recipients can access and read data. Integrity: Data integrity assures users that the information has not been altered in transmission, from origin to destination. Availability: Data availability assures users of timely and reliable access to data services for authorized users. Check Your Understanding—Reliable Networks (1.6.6) Refer to the online course to complete this activity. NETWORK TRENDS (1.7) The network environment continues to evolve, providing new experiences and opportunities for end users. The network is now capable of delivering services and applications in a manner that was once only a dream. Recent Trends (1.7.1) You know a lot about networks now, including what they are made of, how they connect us, and what is needed to keep them reliable. But networks, like everything else, continue to change. You, as a NetAcad student, need to know about a few trends in networking. As new technologies and end-user devices come to market, businesses and consumers must continue to adjust to the ever-changing network environment. Several networking trends affect organizations and consumers: Bring your own device (BYOD) Online collaboration Video communications Cloud computing Bring Your Own Device (BYOD)

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