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Troubleshooting Cisco Nexus Switches and NX-OS

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  • Sample Content
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  • Copyright 2018
  • Dimensions: 7-3/8" x 9-1/8"
  • Pages: 1072
  • Edition: 1st
  • eBook (Watermarked)
  • ISBN-10: 0-13-478321-2
  • ISBN-13: 978-0-13-478321-5

The definitive deep-dive guide to hardware and software troubleshooting on Cisco Nexus switches

The Cisco Nexus platform and NX-OS switch operating system combine to deliver unprecedented speed, capacity, resilience, and flexibility in today's data center networks. Troubleshooting Cisco Nexus Switches and NX-OS is your single reference for quickly identifying and solving problems with these business-critical technologies.

Three expert authors draw on deep experience with large Cisco customers, emphasizing the most common issues in real-world deployments, including problems that have caused major data center outages. Their authoritative, hands-on guidance addresses both features and architecture, helping you troubleshoot both control plane forwarding and data plane/data path problems and use NX-OS APIs to automate and simplify troubleshooting. Throughout, you'll find real-world configurations, intuitive illustrations, and practical insights into key platform-specific behaviors.

This is an indispensable technical resource for all Cisco network consultants, system/support engineers, network operations professionals, and CCNP/CCIE certification candidates working in the data center domain.

·         Understand the NX-OS operating system and its powerful troubleshooting tools

·         Solve problems with cards, hardware drops, fabrics, and CoPP policies

·         Troubleshoot network packet switching and forwarding

·         Properly design, implement, and troubleshoot issues related to Virtual Port Channels (VPC and VPC+)

·         Optimize routing through filtering or path manipulation

·         Optimize IP/IPv6 services and FHRP protocols (including HSRP, VRRP, and Anycast HSRP)

·         Troubleshoot EIGRP, OSPF, and IS-IS neighbor relationships and routing paths

·         Identify and resolve issues with Nexus route maps

·         Locate problems with BGP neighbor adjacencies and enhance path selection

·         Troubleshoot high availability components (BFD, SSO, ISSU, and GIR)

·         Understand multicast protocols and troubleshooting techniques

·         Identify and solve problems with OTV

·         Use NX-OS APIs to automate troubleshooting and administrative tasks


Coming Soon: Bonus chapter "Troubleshooting VXLAN EVPN" will be available here in July 2018.

Sample Pages

Download the sample pages (includes Chapter 14 and the Index)

Table of Contents

Foreword xxvi

Introduction xxvii

Part I Introduction to Troubleshooting Nexus Switches

Chapter 1 Introduction to Nexus Operating System (NX-OS) 1

Nexus Platforms Overview 2

    Nexus 2000 Series 2

    Nexus 3000 Series 3

    Nexus 5000 Series 4

    Nexus 6000 Series 4

    Nexus 7000 Series 5

    Nexus 9000 Series 6

NX-OS Architecture 8

    The Kernel 9

    System Manager (sysmgr) 9

    Messages and Transactional Services 11

    Persistent Storage Services 13

    Feature Manager 14

    NX-OS Line Card Microcode 17

    File Systems 19

Understanding NX-OS Software Releases and Packaging 25

    Software Maintenance Upgrades 27

    Licensing 28

NX-OS High-Availability Infrastructure 28

    Supervisor Redundancy 29

    ISSU 34

NX-OS Virtualization Features 35

    Virtual Device Contexts 35

    Virtual Routing and Forwarding 37

    Virtual Port Channel 37

Management and Operations Capabilities 39

    NX-OS Advanced CLI 39

    Technical Support Files 44

    Accounting Log 45

    Feature Event-History 46

    Debug Options: Log File and Filters 47

    Configuration Checkpoint and Rollback 48

    Consistency Checkers 49

    Feature Scheduler, EEM, and Python 50

    Bash Shell 51

Summary 51

References 51

Chapter 2 NX-OS Troubleshooting Tools 53

Packet Capture: Network Sniffer 53

    Encapsulated Remote SPAN 57

    SPAN on Latency and Drop 60

Nexus Platform Tools 63

    Ethanalyzer 63

    Packet Tracer 71

NetFlow 72

    NetFlow Configuration 73

    NetFlow Sampling 77

    sFlow 78

Network Time Protocol 81

Embedded Event Manager 83

Logging 87

    Debug Logfiles 90

    Accounting Log 91

    Event-History 92

Summary 93

References 93

Chapter 3 Troubleshooting Nexus Platform Issues 95

Troubleshooting Hardware Issues 95

    Generic Online Diagnostic Tests 98

    Nexus Device Health Checks 108

    Nexus Fabric Extenders 124

Virtual Device Context 130

    VDC Resource Template 131

    Configuring VDC 133

    VDC Initialization 134

    Out-of-Band and In-Band Management 137

    VDC Management 137

Troubleshooting NX-OS System Components 142

    Message and Transaction Services 144

    Netstack and Packet Manager 148

    ARP and Adjacency Manager 160

    EthPM and Port-Client 175

HWRL, CoPP, and System QoS 179

    MTU Settings 192

Summary 195

References 196

Part II Troubleshooting Layer 2 Forwarding

Chapter 4 Nexus Switching 197

Network Layer 2 Communication Overview 197

Virtual LANs 200

    VLAN Creation 201

    Access Ports 203

    Trunk Ports 204

    Private VLANS 207

Spanning Tree Protocol Fundamentals 218

    IEEE 802.1D Spanning Tree Protocol 219

    Rapid Spanning Tree Protocol 220

    Multiple Spanning-Tree Protocol (MST) 236

Detecting and Remediating Forwarding Loops 241

    MAC Address Notifications 242

    BPDU Guard 243

    BPDU Filter 244

    Problems with Unidirectional Links 245

Summary 252

References 254

Chapter 5 Port-Channels, Virtual Port-Channels, and FabricPath 255

Port-Channels 255

    Basic Port-Channel Configuration 259

    Verifying Port-Channel Status 260

    Verifying LACP Packets 262

    Advanced LACP Configuration Options 265

    LACP System Priority 268

    Port-Channel Member Interface Consistency 271

    Troubleshooting LACP Interface Establishment 272

    Troubleshooting Traffic Load-Balancing 272

Virtual Port-Channel 274

    vPC Fundamentals 275

    vPC Configuration 278

    vPC Verification 280

    Advanced vPC Features 288

FabricPath 294

    FabricPath Terminologies and Components 296

    FabricPath Packet Flow 297

    FabricPath Configuration 300

    FabricPath Verification and Troubleshooting 303

    FabricPath Devices 310

Emulated Switch and vPC+ 310

    vPC+ Configuration 311

    vPC+ Verification and Troubleshooting 314

Summary 320

References 320

Part III Troubleshooting Layer 3 Routing

Chapter 6 Troubleshooting IP and IPv6 Services 321

IP SLA 321

    ICMP Echo Probe 322

    UDP Echo Probe 324

    UDP Jitter Probe 325

    TCP Connect Probe 328

Object Tracking 329

    Object Tracking for the Interface 330

    Object Tracking for Route State 330

    Object Tracking for Track-List State 332

    Using Track Objects with Static Routes 334

IPv4 Services 335

    DHCP Relay 335

    DHCP Snooping 341

    Dynamic ARP Inspection 345

    IP Source Guard 349

    Unicast RPF 351

IPv6 Services 352

    Neighbor Discovery 352

    IPv6 Address Assignment 357

    IPv6 First-Hop Security 362

First-Hop Redundancy Protocol 370

    HSRP 370

    VRRP 380

    GLBP 385

Summary 391

Chapter 7 Troubleshooting Enhanced Interior Gateway Routing Protocol (EIGRP) 393

EIGRP Fundamentals 393

    Topology Table 395

    Path Metric Calculation 396

    EIGRP Communication 399

    Baseline EIGRP Configuration 399

Troubleshooting EIGRP Neighbor Adjacency 401

    Verification of Active Interfaces 402

    Passive Interface 403

    Verification of EIGRP Packets 405

    Connectivity Must Exist Using the Primary Subnet 409

    EIGRP ASN Mismatch 412

    Mismatch K Values 413

    Problems with Hello and Hold Timers 414

    EIGRP Authentication Issues 416

Troubleshooting Path Selection and Missing Routes 419

    Load Balancing 421

    Stub 421

    Maximum-Hops 424

    Distribute List 426

    Offset Lists 427

    Interface-Based Settings 430

    Redistribution 430

    Classic Metrics vs. Wide Metrics 433

Problems with Convergence 439

    Active Query 441

    Stuck in Active 443

Summary 446

References 447

Chapter 8 Troubleshooting Open Shortest Path First (OSPF) 449

OSPF Fundamentals 449

    Inter-Router Communication 450

    OSPF Hello Packets 450

    Neighbor States 451

    Designated Routers 452

    Areas 453

    Link State Advertisements 453

Troubleshooting OSPF Neighbor Adjacency 456

    Baseline OSPF Configuration 456

    OSPF Neighbor Verification 458

    Confirmation of OSPF Interfaces 460

    Passive Interface 461

    Verification of OSPF Packets 463

    Connectivity Must Exist Using the Primary Subnet 468

    MTU Requirements 469

    Unique Router-ID 471

    Interface Area Numbers Must Match 471

    OSPF Stub (Area Flags) Settings Must Match 473

    DR Requirements 474

    Timers 476

    Authentication 478

Troubleshooting Missing Routes 482

    Discontiguous Network 482

    Duplicate Router ID 485

    Filtering Routes 487

    Redistribution 487

    OSPF Forwarding Address 488

Troubleshooting OSPF Path Selection 494

    Intra-Area Routes 494

    Inter-Area Routes 495

    External Route Selection 495

    E1 and N1 External Routes 496

    E2 and N2 External Routes 497

    Problems with Intermixed RFC 1583 and RFC 2328 Devices 499

    Interface Link Costs 500

Summary 504

References 505

Chapter 9 Troubleshooting Intermediate System-Intermediate System (IS-IS) 507

IS-IS Fundamentals 507

    Areas 508

    NET Addressing 509

    Inter-Router Communication 511

    IS Protocol Header 511

    TLVs 512

    IS PDU Addressing 512

    IS-IS Hello (IIH) Packets 513

    Link-State Packets 515

    Designated Intermediate System 516

    Path Selection 517

Troubleshooting IS-IS Neighbor Adjacency 518

    Baseline IS-IS Configuration 518

    IS-IS Neighbor Verification 520

    Confirmation of IS-IS Interfaces 523

    Passive Interface 526

    Verification of IS-IS Packets 528

    Connectivity Must Exist Using the Primary Subnet 535

    MTU Requirements 537

    Unique System-ID 539

    Area Must Match Between L1 Adjacencies 539

    Checking IS-IS Adjacency Capabilities 541

    DIS Requirements 543

    IIH Authentication 544

Troubleshooting Missing Routes 546

    Duplicate System ID 546

    Interface Link Costs 549

    Mismatch of Metric Modes 553

    L1 to L2 Route Propagations 556

    Suboptimal Routing 562

    Redistribution 566

Summary 567

References 568

Chapter 10 Troubleshooting Nexus Route-Maps 569

Conditional Matching 569

    Access Control Lists 569

    ACLs and ACL Manager Component 570

    Prefix Matching and Prefix-Lists 577

Route-Maps 581

    Conditional Matching 582

    Optional Actions 586

    Incomplete Configuration of Routing Policies 586

    Diagnosing Route Policy Manger 586

Policy-Based Routing 591

Summary 594

References 595

Chapter 11 Troubleshooting BGP 597

BGP Fundamentals 597

    Address Families 598

    Path Attributes 599

    Loop Prevention 599

BGP Sessions 600

    BGP Identifier 601

    BGP Messages 601

    BGP Neighbor States 602

    BGP Configuration and Verification 605

Troubleshooting BGP Peering Issues 609

    Troubleshooting BGP Peering Down Issues 609

    Demystifying BGP Notifications 619

    Troubleshooting IPv6 Peers 621

    BGP Peer Flapping Issues 622

BGP Route Processing and Route Propagation 630

    BGP Route Advertisement 631

    BGP Best Path Calculation 636

    BGP Multipath 640

    BGP Update Generation Process 643

    BGP Convergence 646

Scaling BGP 649

    Tuning BGP Memory 650

    Soft Reconfiguration Inbound Versus Route Refresh 654

    Scaling BGP with Route-Reflectors 657

    Maximum Prefixes 659

    BGP Max AS 662

BGP Route Filtering and Route Policies 662

    Prefix-List-Based Filtering 663

    Filter-Lists 669

BGP Route-Maps 673

    Regular Expressions (RegEx) 676

    AS-Path Access List 684

    BGP Communities 684

Looking Glass and Route Servers 687

Logs Collection 687

Summary 687

Further Reading 688

References 688

Part IV Troubleshooting High Availability

Chapter 12 High Availability 689

Bidirectional Forwarding Detection 689

    Asynchronous Mode 691

    Asynchronous Mode with Echo Function 693

    Configuring and Verifying BFD Sessions 693

Nexus High Availability 707

    Stateful Switchover 707

    ISSU 713

Graceful Insertion and Removal 719

    Custom Maintenance Profile 727

Summary 731

References 732

Part V Multicast Network Traffic

Chapter 13 Troubleshooting Multicast 733

Multicast Fundamentals 734

    Multicast Terminology 735

    Layer 2 Multicast Addresses 738

    Layer 3 Multicast Addresses 739

NX-OS Multicast Architecture 741

    Replication 744

    Protecting the Central Processing Unit 745

    NX-OS Multicast Implementation 747

IGMP 750

    IGMPv2 751

    IGMPv3 752

    IGMP Snooping 756

    IGMP Verification 761

PIM Multicast 771

    PIM Protocol State and Trees 772

    PIM Message Types 773

    PIM Interface and Neighbor Verification 780

    PIM Any Source Multicast 785

    PIM Bidirectional 799

    PIM RP Configuration 811

    PIM Source Specific Multicast 841

Multicast and Virtual Port-Channel 848

    vPC-Connected Source 849

    vPC-Connected Receiver 861

    vPC Considerations for Multicast Traffic 870

Ethanalyzer Examples 871

Summary 871

References 872

Part VI Troubleshooting Nexus Tunneling

Chapter 14 Troubleshooting Overlay Transport Virtualization (OTV) 875

OTV Fundamentals 875

    Flood Control and Broadcast Optimization 877

    Supported OTV Platforms 878

    OTV Terminology 878

    Deploying OTV 881

Understanding and Verifying the OTV Control Plane 885

    OTV Multicast Mode 887

    OTV IS-IS Adjacency Verification 888

    OTV IS-IS Topology Table 898

    OTV IS-IS Authentication 905

    Adjacency Server Mode 907

    OTV Control Plane Policing (CoPP) 912

Understanding and Verifying the OTV Data Plane 913

    OTV ARP Resolution and ARP-ND-Cache 915

    Broadcasts 917

    Unknown Unicast Frames 918

    OTV Unicast Traffic with a Multicast Enabled Transport 919

    OTV Multicast Traffic with a Multicast Enabled Transport 924

    OTV Multicast Traffic with a Unicast Transport (Adjacency Server Mode) 932

Advanced OTV Features 937

    First Hop Routing Protocol Localization 938

    Multihoming 939

    Ingress Routing Optimization 940

    VLAN Translation 941

    OTV Tunnel Depolarization 942

    OTV Fast Failure Detection 944

Summary 946

References 947

Part VII Network Programmability

Chapter 15 Programmability and Automation 949

Introduction to Automation and Programmability 949

Introduction to Open NX-OS 950

    Shells and Scripting 951

NX-SDK 964

NX-API 968

Summary 975

References 975

9781587145056    TOC    4/24/2018


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