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Troubleshooting Cisco Nexus Switches and NX-OS

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  • About
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  • Troubleshoot data center deployments with NX-OS
  • Master techniques for minimizing network outages and increasing network performance and scalability
  • Gain an in-depth understanding of Nexus and NX-OS architecture at the packet level to become a more effective troubleshooter
  • Learn detailed troubleshooting techniques for unicast and multicast forwarding issues
  • Master key concepts and techniques for troubleshooting at Layer 2, including FabricPath, vPC and vPC+

  • Copyright 2018
  • Dimensions: 7-3/8" x 9-1/8"
  • Pages: 1072
  • Edition: 1st
  • Book
  • ISBN-10: 1-58714-505-7
  • ISBN-13: 978-1-58714-505-6

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

Online Sample Chapter

NX-OS Troubleshooting Tools

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


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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