Introduction Part I Forwarding Chapter 1 Packet Forwarding 2 “Do I Know This Already?” Quiz 2 Foundation Topics 3 Network Device Communication 3 Layer 2 Forwarding 4 Layer 3 Forwarding 19 Forwarding Architectures 26 Process Switching 26 Software CEF 29 Hardware CEF 30 SDM Templates 30 Exam Preparation Tasks 32 Use the Command Reference to Check Your Memory 33 References in This Chapter 34 Part II Layer 2 Chapter 2 Spanning Tree Protocol 36 “Do I Know This Already?” Quiz 36 Foundation Topics 38 Spanning Tree Protocol Fundamentals 38 IEEE 802.1D STP 38 Building the STP Topology 41 STP Topology Changes 49 Rapid Spanning Tree Protocol 53 RSTP (802.1W) Port States 54 RSTP (802.1W) Port Roles 54 RSTP (802.1W) Port Types 54 Building the RSTP Topology 55 RSTP Convergence 55 Exam Preparation Tasks 56 Use the Command Reference to Check Your Memory 56 Chapter 3 Advanced STP Tuning 58 “Do I Know This Already?” Quiz 58 Foundation Topics 59 STP Topology Tuning 59 Placing the Root Bridge 60 Modifying STP Root Port and Blocked Switch Port Locations 63 Modifying STP Port Priority 66 Additional STP Protection Mechanisms 67 Root Guard 68 STP Portfast 68 BPDU Guard 70 BPDU Filter 72 Problems with Unidirectional Links 73 Exam Preparation Tasks 76 Use the Command Reference to Check Your Memory 77 Chapter 4 Multiple Spanning Tree Protocol 80 “Do I Know This Already?” Quiz 80 Foundation Topics 81 Multiple Spanning Tree Protocol 81 MST Instances (MSTIs) 83 MST Configuration 84 MST Verification 85 MST Tuning 87 Common MST Misconfigurations 89 MST Region Boundary 90 Exam Preparation Tasks 92 Use the Command Reference to Check Your Memory 92 Chapter 5 VLAN Trunks and EtherChannel Bundles 94 “Do I Know This Already?” Quiz 94 Foundation Topics 96 VLAN Trunking Protocol 96 VTP Communication 97 VTP Configuration 98 VTP Verification 99 Dynamic Trunking Protocol 101 EtherChannel Bundle 104 Dynamic Link Aggregation Protocols 106 Verifying EtherChannel Status 108 Viewing EtherChannel Neighbors 110 Verifying EtherChannel Packets 113 Advanced LACP Configuration Options 114 Troubleshooting EtherChannel Bundles 118 Load Balancing Traffic with EtherChannel Bundles 119 Exam Preparation Tasks 121 Use the Command Reference to Check Your Memory 121 Part III Routing Chapter 6 IP Routing Essentials 124 “Do I Know This Already?” Quiz 124 Foundation Topics 126 Routing Protocol Overview 126 Distance Vector Algorithms 128 Enhanced Distance Vector Algorithms 129 Link-State Algorithms 130 Path Vector Algorithm 131 Path Selection 132 Prefix Length 133 Administrative Distance 133 Metrics 135 Static Routing 137 Static Route Types 138 Floating Static Routing 141 Static Routes to Null Interfaces 143 IPv6 Static Routes 145 Policy-based Routing 146 Virtual Routing and Forwarding 149 Exam Preparation Tasks 151 Use the Command Reference to Check Your Memory 153 Chapter 7 EIGRP 154 “Do I Know This Already?” Quiz 154 Foundation Topics 156 EIGRP Fundamentals 156 Autonomous Systems 157 EIGRP Terminology 157 Topology Table 159 EIGRP Neighbors 160 Path Metric Calculation 160 Wide Metrics 162 Metric Backward Compatibility 163 Load Balancing 163 Failure Detection and Timers 164 Convergence 164 Route Summarization 166 Exam Preparation Tasks 167 References in This Chapter 168 Chapter 8 OSPF 170 “Do I Know This Already?” Quiz 170 Foundation Topics 172 OSPF Fundamentals 172 Inter-Router Communication 174 OSPF Hello Packets 175 Router ID 175 Neighbors 175 Designated Router and Backup Designated Router 176 OSPF Configuration 178 OSPF Network Statement 178 Interface-Specific Configuration 180 Statically Setting the Router ID 180 Passive Interfaces 181 Requirements for Neighbor Adjacency 181 Sample Topology and Configuration 181 Confirmation of Interfaces 184 Verification of OSPF Neighbor Adjacencies 185 Verification of OSPF Routes 186 Default Route Advertisement 187 Common OSPF Optimizations 188 Link Costs 189 Failure Detection 189 DR Placement 190 OSPF Network Types 194 Exam Preparation Tasks 198 Use the Command Reference to Check Your Memory 199 References in This Chapter 200 Chapter 9 Advanced OSPF 202 “Do I Know This Already?” Quiz 202 Foundation Topics 204 Areas 204 Area ID 207 OSPF Route Types 207 Link-State Advertisements 209 LSA Sequences 210 LSA Age and Flooding 210 LSA Types 210 Discontiguous Networks 217 OSPF Path Selection 218 Intra-Area Routes 218 Inter-Area Routes 219 Equal-Cost Multipathing 220 Summarization of Routes 220 Summarization Fundamentals 221 Inter-Area Summarization 222 Summarization Metrics 222 Configuration of Inter-Area Summarization 223 Route Filtering 224 Filtering with Summarization 225 Area Filtering 225 Exam Preparation Tasks 228 Use the Command Reference to Check Your Memory 229 References in This Chapter 229 Chapter 10 OSPFv3 230 “Do I Know This Already?” Quiz 230 Foundation Topics 231 OSPFv3 Fundamentals 231 OSPFv3 Link-State Advertisement 232 OSPFv3 Communication 232 OSPFv3 Configuration 233 OSPFv3 Verification 235 Passive Interface 237 Summarization 238 Network Type 239 IPv4 Support in OSPFv3 240 Exam Preparation Tasks 242 Use the Command Reference to Check Your Memory 242 References in This Chapter 243 Chapter 11 BGP 244 “Do I Know This Already?” Quiz 244 Foundation Topics 246 BGP Fundamentals 246 Autonomous System Numbers 246 Path Attributes 247 Loop Prevention 247 Address Families 248 Inter-Router Communication 248 BGP Neighbor States 253 Basic BGP Configuration 255 Verification of BGP Sessions 257 Route Advertisement 260 Receiving and Viewing Routes 262 BGP Route Advertisements from Indirect Sources 265 IPv4 Route Summarization 268 Aggregate Address 269 Atomic Aggregate 274 Route Aggregation with AS_SET 276 Multiprotocol BGP for IPv6 278 IPv6 Configuration 279 IPv6 Route Summarization 284 Exam Preparation Tasks 285 Use the Command Reference to Check Your Memory 286 References in This Chapter 287 Chapter 12 Advanced BGP 288 “Do I Know This Already?” Quiz 288 Foundation Topics 290 BGP Multihoming 291 Resiliency in Service Providers 291 Internet Transit Routing 292 Branch Transit Routing 293 Conditional Matching 295 Access Control Lists 295 Prefix Matching 297 Regular Expressions (regex) 300 Route Maps 301 Conditional Matching 302 Optional Actions 304 The continue Keyword 305 BGP Route Filtering and Manipulation 306 Distribute List Filtering 307 Prefix List Filtering 308 AS_Path ACL Filtering 309 Route Maps 311 Clearing BGP Connections 313 BGP Communities 313 Well-Known Communities 314 Enabling BGP Community Support 314 Conditionally Matching BGP Communities 315 Setting Private BGP Communities 317 Understanding BGP Path Selection 318 Routing Path Selection Using Longest Match 319 BGP Best Path Overview 320 Exam Preparation Tasks 329 Use the Command Reference to Check Your Memory 331 References in This Chapter 332 Chapter 13 Multicast 334 “Do I Know This Already?” Quiz 334 Foundation Topics 337 Multicast Fundamentals 337 Multicast Addressing 340 Layer 2 Multicast Addresses 342 Internet Group Management Protocol 343 IGMPv2 344 IGMPv3 346 IGMP Snooping 346 Protocol Independent Multicast 349 PIM Distribution Trees 349 PIM Terminology 352 PIM Dense Mode 354 PIM Sparse Mode 357 Reverse Path Forwarding 360 PIM Forwarder 361 Rendezvous Points 363 Static RP 364 Auto-RP 364 PIM Bootstrap Router 366 Exam Preparation Tasks 367 References in This Chapter 369 Part IV Services Chapter 14 Quality of Service (QoS) 370 “Do I Know This Already?” Quiz 371 Foundation Topics 374 The Need for QoS 374 Lack of Bandwidth 374 Latency and Jitter 374 Packet Loss 376 QoS Models 377 Modular QoS CLI 379 Classification and Marking 381 Classification 381 MQC Classification Configuration 382 Marking 385 DSCP Per-Hop Behaviors 387 Scavenger Class 391 Trust Boundary 391 Class-Based Marking Configuration 392 A Practical Example: Wireless QoS 393 Policing and Shaping 394 Placing Policers and Shapers in the Network 395 Markdown 395 Token Bucket Algorithms 395 Class-Based Policing Configuration 398 Types of Policers 399 Congestion Management and Avoidance 406 Congestion Management 406 Congestion-Avoidance Tools 408 CBWFQ Configuration 410 Exam Preparation Tasks 414 Use the Command Reference to Check Your Memory 416 References in This Chapter 417 Chapter 15 IP Services 418 “Do I Know This Already?” Quiz 418 Foundation Topics 420 Time Synchronization 420 Network Time Protocol 420 NTP Configuration 421 Stratum Preference 424 NTP Peers 424 Precision Time Protocol (PTP) 425 PTP Configuration 427 First-Hop Redundancy Protocol 429 Object Tracking 430 Hot Standby Router Protocol 432 Virtual Router Redundancy Protocol 438 Gateway Load Balancing Protocol 441 Network Address Translation 446 NAT Topology 447 Static NAT 449 Pooled NAT 455 Port Address Translation 458 Exam Preparation Tasks 461 Use the Command Reference to Check Your Memory 462 Part V Overlay Chapter 16 Overlay Tunnels 466 “Do I Know This Already?” Quiz 467 Foundation Topics 469 Generic Routing Encapsulation (GRE) Tunnels 469 GRE Tunnel Configuration 470 GRE Configuration Example 472 Problems with Overlay Networks: Recursive Routing 474 IPsec Fundamentals 475 Authentication Header 476 Encapsulating Security Payload 477 Transform Sets 478 Internet Key Exchange 480 IKEv1 480 IPsec VPNs 484 Site-to-Site IPsec Configuration 486 Cisco Locator/ID Separation Protocol (LISP) 495 LISP Architecture and Protocols 497 LISP Operation 499 Virtual Extensible Local Area Network (VXLAN) 504 Exam Preparation Tasks 507 Use the Command Reference to Check Your Memory 509 Part VI Wireless Chapter 17 Wireless Signals and Modulation 510 “Do I Know This Already?” Quiz 510 Foundation Topics 512 Understanding Basic Wireless Theory 512 Understanding Frequency 514 Understanding Phase 519 Measuring Wavelength 519 Understanding RF Power and dB 520 Carrying Data Over an RF Signal 531 Maintaining AP–Client Compatibility 533 Using Multiple Radios to Scale Performance 535 Maximizing the AP–Client Throughput 538 Exam Preparation Tasks 540 Chapter 18 Wireless Infrastructure 542 “Do I Know This Already?” Quiz 542 Foundation Topics 545 Wireless Deployment Models 545 Autonomous Deployment 545 Cisco AP Operation 547 Cisco Wireless Deployments 548 Pairing Lightweight APs and WLCs 552 AP States 552 Discovering a WLC 554 Selecting a WLC 555 Maintaining WLC Availability 556 Segmenting Wireless Configurations 557 Leveraging Antennas for Wireless Coverage 559 Radiation Patterns 560 Gain 562 Beamwidth 563 Polarization 563 Omnidirectional Antennas 564 Directional Antennas 567 Exam Preparation Tasks 570 Chapter 19 Understanding Wireless Roaming and Location Services 572 “Do I Know This Already?” Quiz 572 Foundation Topics 574 Roaming Overview 574 Roaming Between Autonomous APs 574 Intracontroller Roaming 577 Intercontroller Roaming 579 Layer 2 Roaming 579 Layer 3 Roaming 581 Scaling Mobility with Mobility Groups 583 Locating Devices in a Wireless Network 584 Exam Preparation Tasks 587 Chapter 20 Authenticating Wireless Clients 590 “Do I Know This Already?” Quiz 590 Foundation Topics 592 Open Authentication 593 Authenticating with Pre-Shared Key 595 Authenticating with EAP 597 Configuring EAP-Based Authentication with External RADIUS Servers 600 Verifying EAP-Based Authentication Configuration 602 Authenticating with WebAuth 603 Exam Preparation Tasks 606 Chapter 21 Troubleshooting Wireless Connectivity 608 “Do I Know This Already?” Quiz 608 Foundation Topics 610 Troubleshooting Client Connectivity from the WLC 611 Checking the Client's Association and Signal Status 613 Checking the Client Properties 614 Checking the AP Properties 614 Checking the Client Security 615 Troubleshooting the Client 615 Troubleshooting Connectivity Problems at the AP 617 Exam Preparation Tasks 620 Part VII Architecture Chapter 22 Enterprise Network Architecture 622 “Do I Know This Already?” Quiz 622 Foundation Topics 624 Hierarchical LAN Design Model 624 Access Layer 625 Distribution Layer 627 Core Layer 628 High Availability Network Design 629 High Availability Technologies 630 Enterprise Network Architecture Options 632 Two-Tier Design (Collapsed Core) 632 Three-Tier Design 634 Layer 2 Access Layer (STP Based) 634 Layer 3 Access Layer (Routed Access) 636 Simplified Campus Design 637 Software-Defined Access (SD-Access) Design 640 Exam Preparation Tasks 640 Chapter 23 Fabric Technologies 642 “Do I Know This Already?” Quiz 643 Foundation Topics 645 Software-Defined Access (SD-Access) 645 What Is SD-Access? 646 SD-Access Architecture 646 Physical Layer 647 Controller Layer 656 Management Layer 657 Software-Defined WAN (SD-WAN) 661 Cisco SD-WAN Architecture 661 vBond Orchestrator 662 vManage NMS 663 vSmart Controller 663 Cisco SD-WAN Edge Devices 663 vAnalytics 664 Cisco SD-WAN Cloud OnRamp 664 SD-WAN Policy 665 Application-Aware Routing 665 Cloud OnRamp for SaaS 666 Cloud OnRamp for IaaS 668 Exam Preparation Tasks 669 Chapter 24 Network Assurance 672 Do I Know This Already? 672 Foundation Topics 674 Network Diagnostic Tools 675 ping 675 traceroute 680 Debugging 685 Conditional Debugging 692 Simple Network Management Protocol (SNMP) 695 syslog 701 NetFlow and Flexible NetFlow 706 Switched Port Analyzer (SPAN) Technologies 716 Local SPAN 717 Specifying the Source Ports 717 Remote SPAN (RSPAN) 720 Encapsulated Remote SPAN (ERSPAN) 722 IP SLA 724 Cisco DNA Center Assurance 728 Exam Preparation Tasks 734 Part VIII Security Chapter 25 Secure Network Access Control 736 “Do I Know This Already?” Quiz 736 Foundation Topics 738 Network Security Design for Threat Defense 738 Next-Generation Endpoint Security 741 Cisco Talos 741 Cisco Secure Malware Analytics (Threat Grid) 742 Cisco Advanced Malware Protection (AMP) 742 Cisco Secure Client (AnyConnect) 744 Cisco Umbrella 744 Cisco Secure Web Appliance (WSA) 746 Cisco Secure Email (ESA) 748 Cisco Secure IPS (FirePOWER NGIPS) 749 Cisco Secure Firewall (NGFW) 751 Cisco Secure Firewall Management Center (FMC) 753 Cisco Secure Network Analytics (Stealthwatch Enterprise) 753 Cisco Secure Cloud Analytics (Stealthwatch Cloud) 755 Cisco Identity Services Engine (ISE) 756 Network Access Control (NAC) 758 802.1x 758 MAC Authentication Bypass (MAB) 762 Web Authentication (WebAuth) 764 Enhanced Flexible Authentication (FlexAuth) 766 Cisco Identity-Based Networking Services (IBNS) 2.0 766 Cisco TrustSec 766 MACsec 772 Exam Preparation Tasks 774 Chapter 26 Network Device Access Control and Infrastructure Security 778 “Do I Know This Already?” Quiz 778 Foundation Topics 781 Access Control Lists (ACLs) 781 Numbered Standard ACLs 782 Numbered Extended ACLs 783 Named ACLs 784 Port ACLs (PACLs) and VLAN ACLs (VACLs) 785 PACL, VACL, and RACL Interaction 787 Terminal Lines and Password Protection 788 Password Types 789 Password Encryption 789 Username and Password Authentication 790 Configuring Line Local Password Authentication 790 Verifying Line Local Password Authentication 791 Configuring Line Local Username and Password Authentication 792 Verifying Line Local Username and Password Authentication 792 Privilege Levels and Role-Based Access Control (RBAC) 793 Verifying Privilege Levels 794 Controlling Access to vty Lines with ACLs 796 Verifying Access to vty Lines with ACLs 796 Controlling Access to vty Lines Using Transport Input 797 Verifying Access to vty Lines Using Transport Input 798 Enabling SSH vty Access 800 Auxiliary Port 802 EXEC Timeout 802 Absolute Timeout 802 Authentication, Authorization, and Accounting (AAA) 803 TACACS+ 803 RADIUS 804 Configuring AAA for Network Device Access Control 805 Verifying AAA Configuration 809 Zone-Based Firewall (ZBFW) 809 The Self Zone 810 The Default Zone 810 ZBFW Configuration 811 Verifying ZBFW 816 Control Plane Policing (CoPP) 817 Configuring ACLs for CoPP 817 Configuring Class Maps for CoPP 818 Configuring the Policy Map for CoPP 819 Applying the CoPP Policy Map 819 Verifying the CoPP Policy 820 Device Hardening 822 Exam Preparation Tasks 823 Use the Command Reference to Check Your Memory 824 Part IX SDN Chapter 27 Virtualization 826 “Do I Know This Already?” Quiz 826 Foundation Topics 828 Server Virtualization 828 Virtual Machines 828 Containers 830 Virtual Switching 831 Network Functions Virtualization 833 NFV Infrastructure 834 Virtual Network Functions 834 Virtualized Infrastructure Manager 834 Element Managers 835 Management and Orchestration 836 Operations Support System (OSS)/Business Support System (BSS) 836 VNF Performance 836 Cisco Enterprise Network Functions Virtualization (ENFV) 842 Exam Preparation Tasks 847 Chapter 28 Foundational Network Programmability Concepts 850 “Do I Know This Already?” Quiz 850 Foundation Topics 854 Command-Line Interface 854 Application Programming Interface 855 Northbound API 855 Southbound API 856 Representational State Transfer (REST) APIs 856 API Tools and Resources 857 Introduction to Postman 857 Data Formats (XML and JSON) 860 Cisco DNA Center APIs 862 Cisco vManage APIs 867 Data Models and Supporting Protocols 870 YANG Data Models 870 Cisco DevNet 877 Documentation 878 Learn 878 Technologies 878 Community 879 Events 879 GitHub 880 Basic Python Components and Scripts 882 Exam Preparation Tasks 889 References in This Chapter 890 Chapter 29 Introduction to Automation Tools 892 “Do I Know This Already?” Quiz 892 Foundation Topics 894 Embedded Event Manager 894 EEM Applets 895 EEM and Tcl Scripts 899 EEM Summary 901 Agent-Based Automation Tools 902 Puppet 902 Chef 904 SaltStack (Agent and Server Mode) 909 Agentless Automation Tools 912 Ansible 912 Puppet Bolt 922 SaltStack SSH (Server-Only Mode) 923 Comparing Tools 924 Exam Preparation Tasks 925 Chapter 30 Final Preparation 926 Getting Ready 926 Tools for Final Preparation 927 Pearson Test Prep Practice Test Software and Questions on the Website 927 Customizing Your Exams 928 Updating Your Exams 929 Premium Edition 929 Chapter-Ending Review Tools 930 Suggested Plan for Final Review/Study 930 Summary 930 Chapter 31 ENCOR 350-401 Exam Updates 932 The Purpose of This Chapter 932 About Possible Exam Updates 932 Impact on You and Your Study Plan 933 News About the Next Exam Release 934 Updated Technical Content 934 Appendix A Answers to the “Do I Know This Already?” Questions 936 Glossary 956 Online Elements Appendix B Memory Tables Appendix C Memory Tables Answer Key Appendix D Study Planner Glossary 9780138216764 TOC 8/17/2023

This second edition has an updated Wireless Section to accommodate the Cisco IOS XE-based wireless LAN controllers. The wireless chapters now include enhanced security features like 802.1x and EAPOL, wireless segmentation capabilities, and troubleshooting client connectivity via the GUI. The Routing Section has also been updated to include topics such as Policy Based Routing. The chapter on Quality of Service has been expanded to include the Modular QoS Command Line commands to help readers understand actual QoS  configurations. The chapter on Cisco Security has been updated to match changes within the Cisco security portfolio.  The Enterprise Network Architecture chapter includes a  new section on High Availability Network Design.