Ccde study guide top-down network design 2nd edition năm 2024

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CCDE Study Guide is written and reviewed by CCDE engineers and helps you to both improve your design skills and to study for and pass the CCDE exam. Network design is an art, combining broad technology knowledge and experience. This book covers a broad number of technologies, protocols and design options, and considerations that can bring these aspects together and show how they can be used and thought about based on different requirements and business goals. Therefore, this book does not attempt to teach foundational technology knowledge, instead each section:

  • Highlights, discusses, and compares the limitations and advantages of the different design options in terms of scalability, performance, flexibility, availability, complexity, security, and so on to simplify the job and help you understand what technology, protocol, or design options should be selected and why, based on the business or application requirements or to fix a broken design that need to be optimized
  • Covers design aspects of different protocols and technologies, and how they map with different requirements
  • Highlights drivers toward using these technologies whether it is intended for enterprise or service provider network, depending on the topic and technology

Using a business-driven approach, CCDE Study Guide helps you analyze business and technical requirements and develop network designs that are based on these business needs and goals, taking into account both the technical and non-technical design constraints. The various “scenario-based” design examples discussed in this book will help you craft design approaches and requirements analysis on such topics as converged enterprise network architectures, service provider network architectures, and data centers. The book also addresses high availability, IPv6, multicast, QoS, security, and network management design considerations, presenting you with an in-depth evaluation of a broad range of technologies and environments.

Whether you are preparing for the CCDE exam or simply wish to gain better insight into the art of network design in a variety of environments, this book helps you learn how to think like an expert network designer as well as analyze and compare the different design options, principles, and protocols based on different design requirements.

  • Master a business-driven approach to designing enterprise, service provider, and data center networks
  • Analyze the design impact of business, functional, and application requirements Learn from scenario-based examples, including converged enterprise networks, service provider networks, and cloud-based data centers

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CCDE Study Guide: Enterprise Campus Architecture Design

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Table of Contents

Introduction xx

Part I Business-Driven Strategic Network Design 1

Chapter 1 Network Design Requirements: Analysis and Design Principles 3

Design Scope 4

Business Requirements 5

Business Continuity 6

Elasticity to Support the Strategic Business Trends 7

IT as a Business Innovation Enabler 8

The Nature of the Business 9

Business Priorities 9

Functional Requirements 9

Technical Requirements 10

Application Requirements 10

Design Constraints 12

Crafting the Design Requirements 13

Planning 16

Decision Tree 17

Decision Matrix 17

Planning Approaches 18

Strategic Balance 18

Network Design Principles 19

Reliability and Resiliency 19

Modularity 20

Reliable and Manageable Scalability 21

Fault Isolation and Simplicity 22

Hierarchy 23

Responsiveness 25

Holistic Design Approach 25

Physical Layout Considerations 26

No Gold Plating 29

Summary 29

Part II Next Generation - Converged Enterprise Network Architectures 31

Chapter 2 Enterprise Layer 2 and Layer 3 Design 35

Enterprise Layer 2 LAN Design Considerations 35

Spanning Tree Protocol 36

VLANs and Trunking 37

Link Aggregation 37

First Hop Redundancy Protocol and Spanning Tree 38

Enterprise Layer 2 LAN Common Design Options 40

Layer 2 Design Models: STP Based (Classical Model) 40

Layer 2 Design Model: Switch Clustering Based (Virtual Switch) 41

Layer 2 Design Model: Daisy-Chained Access Switches 42

Layer 2 LAN Design Recommendations 43

Enterprise Layer 3 Routing Design Considerations 43

IP Routing and Forwarding Concept Review 43

Link-State Routing Protocol Design Considerations 45

Link-State over Hub-and-Spoke Topology 45

Link-State over Full-Mesh Topology 48

OSPF Area Types 49

OSPF Versus IS-IS 53

Further Reading 53

EIGRP Design Considerations 54

EIGRP: Hub and Spoke 55

EIGRP Stub Route Leaking: Hub-and-Spoke Topology 56

EIGRP: Ring Topology 58

EIGRP: Full-Mesh Topology 58

EIGRP Route Propagation Considerations 59

Further Reading 60

Hiding Topology and Reachability Information Design Considerations 60

IGP Flooding Domains Design Considerations 62

Link-State Flooding Domain Structure 63

EIGRP Flooding Domains Structure 69

Routing Domain Logical Separation 70

Route Summarization 76

Summary Black Holes 78

Suboptimal Routing 80

IGP Traffic Engineering and Path Selection: Summary 83


IS-IS 84


Summary of IGP Characteristics 84

BGP Design Considerations 85

Interdomain Routing 86

BGP Attributes and Path Selection 88

BGP as the Enterprise Core Routing Protocol 89

Enterprise Core Routing Design Models with BGP 90

BGP Shortest Path over the Enterprise Core 94

BGP Scalability Design Options and Considerations 96

BGP Route Reflection 96

Update Grouping 102

BGP Confederation 103

Confederation Versus Route Reflection 105

Further Reading 106

Route Redistribution Design Considerations 107

Single Redistribution Boundary Point 107

Multiple Redistribution Boundary Points 108

Metric Transformation 109

Administrative Distance 110

Route Filtering Versus Route Tagging with Filtering 110

Enterprise Routing Design Recommendations 114

Determining Which Routing Protocol to Use 115

Summary 117

Chapter 3 Enterprise Campus Architecture Design 119

Enterprise Campus: Hierarchical Design Models 119

Three-Tier Model 120

Two-Tier Model 120

Enterprise Campus: Modularity 121

When Is the Core Block Required? 122

Access-Distribution Design Model 123

Enterprise Campus: Layer 3 Routing Design Considerations 126

EIGRP Versus Link State as a Campus IGP 128

Enterprise Campus Network Virtualization 129

Drivers to Consider Network Virtualization 129

Network Virtualization Design Elements 131

Enterprise Network Virtualization Deployment Models 132

Device Virtualization 133

Path Isolation 133

Service Virtualization 136

Summary 141

Further Reading 141

Chapter 4 Enterprise Edge Architecture Design 143

Enterprise WAN Module 143

WAN Transports: Overview 144

Modern WAN Transports (Layer 2 Versus Layer 3) 145

Layer 2 MPLS-Based WAN 146

Layer 3 MPLS-Based WAN 148

Internet as WAN Transport 151

Internet as WAN Transport Advantages and Limitations 152

WAN Transport Models Comparison 153

WAN Module Design Options and Considerations 155

Design Hierarchy of the Enterprise WAN Module 155

WAN Module Access to Aggregation Layer Design Options 156

WAN Edge Connectivity Design Options 158

Single WAN Provider Versus Dual Providers 160

Remote Site (Branch) WAN Design Considerations 161

Internet as WAN Transport (DMVPN Based) 164

Enterprise WAN Module Design Options 166

Option 1: Small to Medium 166

Option 2: Medium to Large 167

Option 3: Large to Very Large 169

WAN Virtualization and Overlays Design Considerations and Techniques 170

WAN Virtualization 172

Over-the-Top WAN Virtualization Design Options (Service Provider Coordinated/Dependent) 174

Over-the-Top WAN Virtualization Design Options (Service Provider Independent) 176

Comparison of Enterprise WAN Transport Virtualization Techniques 181

WAN Virtualization Design Options Decision Tree 183

Enterprise WAN Migration to MPLS VPN Considerations 184

Migrating from Legacy WAN to MPLS L3VPN WAN Scenario 184

Enterprise Internet Edge Design Considerations 188

Internet Edge Architecture Overview 188

Enterprise Multihomed Internet Design Considerations 190

Multihoming Design Concept and Drivers 190

BGP over Multihomed Internet Edge Planning Recommendations 192

BGP Policy Control Attributes for Multihoming 192

Common Internet Multihoming Traffic Engineering Techniques over BGP 194

Scenario 1: Active-Standby 194

Asymmetrical Routing with Multihoming (Issue and Solution) 199

Summary 202

Part III Service Provider Networks Design and Architectures 203

Chapter 5 Service Provider Network Architecture Design 205

Service Provider Network Architecture Building Blocks 207

Point of Presence 208

Service Provider Network Core 211

Service Provider Control Plane Logical Architectures 212

IGP in Service Provider Networks 212

BGP in Service Provider Networks 213

BGP Route Aggregation (ISP Perspective) 213

Hot- and Cold-Potato Routing (SP Perspective) 217

Multiprotocol Label Switching 223

MPLS Label-Switched Path 225

MPLS Deployment Modes 225

Multiprotocol BGP 226

MPLS Traffic Engineering 227

Business and Technical Drivers 227

MPLS-TE Planning 231

MPLS-TE Strategic Planning Approach 231

MPLS-TE Tactical Planning Approach 232

MPLS-TE Design Considerations 233

Constrained Path Calculation 234

MPS-TE Tunnel Placement 237

Routing Domains 239

Forwarding Traffic Via the TE Tunnel 241

Summary 243

Further Reading 244

Chapter 6 Service Provider MPLS VPN Services Design 245


MPLS L3VPN Architecture Components 246

L3VPN Control Plane Components 248

L3VPN Forwarding Plane 251

L3VPN Design Considerations 253

Load Sharing for Multihomed L3VPN CE 253

MPLS L3VPN Topologies 254

MP-BGP VPN Internet Routing 262

PE-CE L3VPN Routing Design 264

PE-CE Routing Design Considerations 265

PE-CE Routing Protocol Selection 266

PE-CE Design Options and Recommendations 266

Layer 2 MPLS VPN (L2VPN) 282

IP NGN Carrier Ethernet 284

Virtual Private Wire Service Design Considerations 287

Transport Models 287

VPWS Control Plane 289

Virtual Private LAN Service Design Considerations 291

VPLS Architecture Building Blocks 292

VPLS Functional Components 292

Virtual Switching Instance 293

VPLS Control Plane 293

VPLS Design Models 294

Ethernet Access Model 298

MPLS Access Model 299

H-VPLS with Provider Backbone Bridging 301

EVPN Design Model (Next-Generation MPLS L2VPN) 307

EVPN BGP Routes and Extended Communities 311

Final Thoughts: L2VPN Business Value and Direction 314

Service Provider Control Plane Scalability 315

IGP Scalability Considerations 316

Route Reflection Design Options in SP Networks 318

Provider Routers as RRs for MPLS-VPN 319

Separate RR for MPLS-VPN and IPv4/v6 319

Separate RR per Service (MPLS-VPN and IPv4/v6) 320

Hierarchical RR 321

Partitioned MPLS-VPN RR 323

Hierarchical LSP (Unified MPLS) 325

Summary 327

Further Reading 327

Chapter 7 Multi-AS Service Provider Network Design 329

Inter-AS Design Options and Considerations 330

Inter-AS Option A: Back-to-Back VRF (VRF-to-VRF) 330

Inter-AS Option B: ASBR to ASBR with MP-eBGP Approach 331

Option B-1: Next-Hop-Self Approach 331

Option B-2: Redistribute Connected Approach 332

Option B-3: Multihop MP-eBGP Approach 334

Inter-AS Option C: Multihop MP-eBGP Between RR 335

Inter-AS Option D 335

Inter-AS IPv6 VPN 336

Inter-AS MPLS-TE 337

Inter-AS L2VPN 338

Inter-AS QoS 343

Comparison of Inter-AS Connectivity Options 344

Carrier Supporting Carrier 346

Non-MPLS Customer over MPLS VPN Carrier 346

MPLS Customer over MPLS VPN Carrier 347

MPLS VPN Customer over MPLS VPN Carrier 348

MPLS VPN Customer over MPLS Carrier 348

MPLS VPN Customer over IP-Only Carrier 349

Acquisition of an MPLS-L3VPN Service Provider Design Scenario 353

Background Information 353

Design Requirements 353

Available Interconnection Options 354

Inter-AS Connectivity Model Selection 355

Proposed Solution 356

Network Merger implementation Plan 358

Summary 358

Part IV Data Center Networks Design 361

Chapter 8 Data Center Networks Design 363

Traditional Data Center Network Architecture 364

STP-Based Data Center Network Architecture 365

mLAG-Based Data Center Network Architecture 367

Next-Generation Data Center Network Design 367

Data Center Virtualization and Cloud-Based Services Overview 368

Drivers Toward New Fabric-Based Data Center Network Architectures 369

Modern Data Center Network Architectures and Overlays 372

Clos Architecture 374

Clos Transport Protocols 376

MAC-in-MAC 377

MAC-in-IP 380

MPLS Based 383

Comparison of Data Center Network Architectures 387

Data Center Interconnect 389

DCI Building Blocks 392

DCI Connectivity Options 393

Routed DCI 394

Layer 2 DCI 398

Dark Fiber-Based DCI 401

Layer 2 DCI over ME Transport 403

TRILL-FabricPath-Based DCI 404

Overlay Transport Virtualization 406

VxLAN-Based DCI 408

DCI Design Considerations 411

SAN Extension 414

DCI Path Optimization Techniques 417

DNS Based 421

Route Health Injection 422

Locator/ID Separation Protocol 423

Summary 428

Further Reading 428

Part V High Availability 429

Chapter 9 Network High-Availability Design 431

Fault Tolerance 434

Fate Sharing and Fault Domains 436

Network Resiliency Design Considerations 438

Device-Level Resiliency 441

Protocol-Level Resiliency 443

Network Restoration 444

Network Protection Approach 454


Summary 469

Further Reading 470

Part VI Other Network Technologies and Services 473

Chapter 10 Design of Other Network Technologies and Services 475

IPv6 Design Considerations 475

IPv6 Business and Technical Drivers 476

IPv6 Addressing Types (Review) 477

Migration and Integration of IPv4 and IPv6 478

Discovery Phase 479

Solution Assessment and Planning 479

Detailed Design 484

Deployment, Monitoring, and Optimization 488

Transition to IPv6: Scenario 488

Network Requirements Analysis 490

Design Approach 490

Further Reading 492

IP Multicast Design Considerations 492

Enterprise Multicast Design Options and Considerations 494

Application Characteristic 494

Multicast IP Address Mapping into Ethernet MAC Address 494

Multicast Layer 3 Routing 497

Multicast BGP 506

Multicast Source Discovery Protocol 507

Embedded RP 509

SP Multicast Design Options and Considerations 510

MVPN (Draft-Rosen Model) 510

MVPN - Label Switch Multicast 511

Next-Generation MVPN 512

Multicast Resiliency Design Considerations 514

Anycast RP 514

Anycast-RP Using PIM 515

Phantom RP 516

Live-Live Streaming 517

First Hop Redundancy Protocol-Aware PIM 519

Final Thoughts on IP Multicast Design 520

Further Reading 520

QoS Design Considerations 521

QoS High Level Design: Business-Driven Approach 521

QoS Architecture 523

QoS DiffServ Architecture and Toolset 523

Traffic Classification and Marking 525