Net. Manage. contents

Table of Contents For

Network Management Systems

Preface xv

Chapter 1 The Network Management Challenge 1

1.1	Introduction 1
1.2	The Internet And Network Management 1
1.3	Internet Structure 2
1.4	Managing An Entity 2
1.5	Internal And External Policies 3
1.6	The State Of Network Management 3
1.7	Network Management In The Gartner Model 4
1.8	Benefits Of Automation 4
1.9	The Lack Of Industry Response 5
1.10	Impact On Business 5
1.11	Distributed Systems And New Abstractions 6
1.12	Remainder Of The Text 7
1.13	Summary 7

PART I Basics And Definitions 9

Chapter 2 A Review Of Network Elements And Services 11

2.1	Introduction 11
2.2	Network Devices And Network Services 11
2.3	Network Elements And Element Management 12
2.4	Effect Of Physical Organization On Management 12
2.5	Examples Of Network Elements And Services 13
2.6	Basic Ethernet Switch 14
2.7	VLAN Switch 15
2.8	Access Point For A Wireless LAN 15
2.9	Cable Modem System 16
2.10	DSL Modem System And DSLAM 17
2.11	CSU\^/\^DSU Used In Wide Area Digital Circuits 18
2.12	Channel Bank 19
2.13	IP Router 19
2.14	Firewall 20
2.15	DNS Server 20
2.16	DHCP Server 21
2.17	Web Server 22
2.18	HTTP Load Balancer 22
2.19	Summary 23

Chapter 3 The Network Management Problem 25

3.1	Introduction 25
3.2	What Is Network Management? 25
3.3	The Scope Of Network Management 26
3.4	Variety And Multi-Vendor Environments 27
3.5	Element And Network Management Systems 28
3.6	Scale And Complexity 29
3.7	Types Of Networks 31
3.8	Classification Of Devices 31
3.9	FCAPS: The Industry Standard Definition 32
3.10	The Motivation For Automation 33
3.11	Why Automation Has Not Occurred 33
3.12	Organization Of Management Software 34
3.13	Summary 36

Chapter 4 Configuration And Operation 39

4.1	Introduction 39
4.2	Intuition For Configuration 39
4.3	Configuration And Protocol Layering 40
	4.3.1	Topology And Layer 2 40
	4.3.2	Logical Subnets And Layer 3 41
	4.3.3	Access And Layer 4 41
	4.3.4	Applications And Layer 5 (or Layer 7) 42
4.4	Dependencies Among Configuration Parameters 43
4.5	Seeking A More Precise Definition Of Configuration 44
4.6	Configuration And Temporal Consequences 44
4.7	Configuration And Global Consistency 45
4.8	Global State And Practical Systems 46
4.9	Configuration And Default Values 46
4.10	Partial State, Automatic Update, And Recovery 47
4.11	Interface Paradigm And Incremental Configuration 48
4.12	Commit And Rollback During Configuration 49
4.13	Automated Rollback And Timeout 50
4.14	Snapshot, Configuration, And Partial State 50
4.15	Separation Of Setup And Activation 51
4.16	Configuring Multiple Network Elements 52
4.17	Summary 52

Chapter 5 Fault Detection And Correction 55

5.1	Introduction 55
5.2	Network Faults 55
5.3	Trouble Reports, Symptoms, And Causes 56
5.4	Troubleshooting And Diagnostics 56
5.5	Monitoring 57
5.6	Baselines 58
5.7	Items That Can Be Monitored 59
5.8	Alarms, Logs, And Polling 59
5.9	Identifying The Cause Of A Fault 60
5.10	Human Failure And Network Faults 62
5.11	Protocol Layering And Faults 62
5.12	Hidden Faults And Automatic Correction 63
5.13	Anomaly Detection And Event Correlation 64
5.14	Fault Prevention 64
5.15	Summary 65

Chapter 6 Accounting And Billing 67

6.1	Introduction 67
6.2	Business Model And Network Charges 67
6.3	Service Level Agreements (SLAs) 68
6.4	Service Fees 68
6.5	Accounting For Flat-Rate Service 69
6.6	Accounting For Use-Based Service 69
6.7	Tiered Levels Of Service 70
6.8	Exceeding Quotas And Penalties 70
6.9	Assessing Financial Penalties 71
6.10	Traffic Policing And Strict Enforcement Of Limits 71
6.11	Technologies For Limiting The Rate Of Traffic 72
6.12	Priorities And Absolute Guarantees 73
6.13	Absolute Bandwidth Guarantees And MPLS 73
6.14	Relative Bandwidth Guarantees And Priorities 73
6.15	Priorities And Types Of Traffic 74
6.16	Peering Agreements And Accounting 74
6.17	Summary 75

Chapter 7 Performance Assessment And Optimization 77

7.1	Introduction 77
7.2	Aspects Of Performance 77
7.3	Items That Can Be Measured 78
7.4	Measures Of Network Performance 78
7.5	Application And Endpoint Sensitivity 79
7.6	Degraded Service, Variance In Traffic, And Congestion 80
7.7	Congestion, Delay, And Utilization 81
7.8	Local And End-To-End Measurements 81
7.9	Passive Observation Vs. Active Probing 82
7.10	Bottlenecks And Future Planning 83
7.11	Capacity Planning 83
7.12	Planning The Capacity Of A Switch 84
7.13	Planning The Capacity Of A Router 84
7.14	Planning The Capacity Of An Internet Connection 85
7.15	Measuring Peak And Average Traffic On A Link 86
7.16	Estimated Peak Utilization And 95\v'-.35m'\s-4t\s0\v'+.35m'\v'-.35m'\s-4h\s0\v'+.35m' Percentile 87
7.17	Relationship Between Average And Peak Utilization 87
7.18	Consequences For Management And The 50/80 Rule 88
7.19	Capacity Planning For A Complex Topology 89
7.20	A Capacity Planning Process 89
	7.20.1	Forecasting Future Load 89
	7.20.2	Measuring Existing Resource Use 90
	7.20.3	A Load Model Based On A Traffic Matrix 90
	7.20.4	Flows And Aggregates 92
	7.20.5	Deriving Estimates And Validation 93
	7.20.6	Experimenting With Possible Changes 93
7.21	Route Changes And Traffic Engineering 94
7.22	Failure Scenarios And Availability 94
7.23	Summary 95

Chapter 8 Security 97

8.1	Introduction 97
8.2	The Illusion Of A Secure Network 97
8.3	Security As A Process 98
8.4	Security Terminology And Concepts 98
8.5	Management Goals Related To Security 99
8.6	Risk Assessment 100
8.7	Security Policies 101
8.8	Acceptable Use Policy 102
8.9	Basic Technologies Used For Security 102
	8.9.1	Encryption Technologies 102
	8.9.2	Perimeter Control Technologies 103
	8.9.3	Content Control Technologies 104
8.10	Management Issues And Security 105
8.11	Security Architecture: Perimeter Vs. Resources 105
8.12	Element Coordination And Firewall Unification 106
8.13	Resource Limits And Denial Of Service 107
8.14	Management of Authentication 107
8.15	Access Control And User Authentication 108
8.16	Management Of Wireless Networks 109
8.17	Security Of The Network 110
8.18	Role-Based Access Control 111
8.19	Audit Trails And Security Logging 112
8.20	Key Management 112
8.21	Summary 113

PART II Tools And Platforms 115

Chapter 9 Management Tools And Technologies 117

9.1	Introduction 117
9.2	The Principle Of Most Recent Change 117
9.3	The Evolution Of Management Tools 118
9.4	Management Tools As Applications 118
9.5	Using A Separate Network For Management 119
9.6	Types Of Management Tools 120
9.7	Physical Layer Testing Tools 121
9.8	Reachability And Connectivity Tools (ping) 122
9.9	Packet Analysis Tools 123
9.10	Discovery Tools 124
9.11	Device Interrogation Interfaces And Tools 126
9.12	Event Monitoring Tools 127
9.13	Triggers, Urgency Levels, And Granularity 127
9.14	Events, Urgency Levels, And Traffic 129
9.15	Performance Monitoring Tools 129
9.16	Flow Analysis Tools 132
9.17	Routing And Traffic Engineering Tools 133
9.18	Configuration Tools 133
9.19	Security Enforcement Tools 134
9.20	Network Planning Tools 134
9.21	Integration Of Management Tools 135
9.22	NOCs And Remote Monitoring 136
9.23	Remote CLI Access 137
9.24	Remote Aggregation Of Management Traffic 138
9.25	Other Tools 140
9.26	Scripting 141
9.27	Summary 141

Chapter 10 Simple Network Management Protocol (SNMP) 143

10.1	Introduction 143
10.2	The Remote Management Paradigm And Applications 143
10.3	Management Functions And Protocol Definition 144
10.4	The Read-Write Paradigm 145
10.5	Arbitrary Operations And Virtual Items 146
10.6	Standards For Network Management Protocols 146
10.7	SNMP Scope And Paradigm 147
10.8	Basic SNMP Commands And Optimizations 148
10.9	Asynchronous Traps And Event Monitoring 148
10.10	Traps, Polling, Bandwidth, And CPU Cycles 149
10.11	Management Information Base (MIB) And Variables 150
10.12	A Hierarchy Of MIB Variable Names 151
10.13	Advantages And Disadvantages Of A Hierarchy 153
10.14	Complex Data Aggregates And MIB Tables 154
10.15	Granularity Of Aggregate Access 155
10.16	Transport Protocols And Interaction 155
10.17	Updates, Messages, And Atomicity 156
10.18	The Remote Monitoring MIB (RMON) 157
10.19	A Manager's View Of MIB Variables 158
10.20	Security And The Community String 159
10.21	Summary 160

Chapter 11 Flow Data And Flow Analysis (NetFlow) 163

11.1	Introduction 163
11.2	Basic Traffic Analysis 163
11.3	The Flow Abstraction 164
11.4	The Two Types Of Flows 165
11.5	The Purpose Of Flow Analysis 166
11.6	Levels Of Flow Aggregation 167
11.7	Online And Offline Flow Analysis 168
11.8	Examples Of Flow Data Analysis 169
11.9	Flow Data Capture And Filtering 171
11.10	Packet Inspection And Classification 173
11.11	Capture For Online And Offline Analysis 174
11.12	Flows Using Packet Content 175
11.13	Flows And Optimized Forwarding 175
11.14	Flow Data Export 177
11.15	Origin Of NetFlow Technology 178
11.16	Basic NetFlow Characteristics 178
11.17	Extensibility And Templates 179
11.18	NetFlow Message Transport And Consequences 180
11.19	Effect Of Configuration Choices 181
11.20	Summary 182

Chapter 12 Routing And Traffic Engineering 185

12.1	Introduction 185
12.2	Definitions Of Forwarding And Routing 185
12.3	Automation And Routing Update Protocols 186
12.4	Routing Basics And Route Metrics 186
	12.4.1	Shortest Paths And Route Metrics 187
	12.4.2	Types And Scope Of Routing 188
12.5	Example Routing Update Protocols 188
12.6	Management Of Routes 189
12.7	The Difficulty Of Route Management 189
12.8	Use Of Routing Metrics To Enforce Policy 190
12.9	Overcoming Automation 191
12.10	Routing And Management Of Quality-of-Service 192
12.11	Traffic Engineering And MPLS Tunnels 193
12.12	Precomputation Of Backup Paths 193
12.13	Combinatorial Optimization And Infeasibility 195
12.14	Precomputation And Fast Convergence For IP Routing 196
12.15	Traffic Engineering, Security, And Load Balancing 196
12.16	Overhead, Convergence, And Routing Protocol Choices 197
12.17	OSPF Areas And The Principle Of Hierarchical Routing 198
12.18	Management Of Routing And Hidden Problems 199
12.19	The Global Nature Of Routing 200
12.20	Summary 201
	For Further Study 202

Chapter 13 Management Scripting 205

13.1	Introduction 205
13.2	Limits Of Configuration 205
13.3	Iterative Improvement Using The Upgrade Paradigm 206
13.4	Extending Functionality Without An Upgrade Cycle 207
13.5	The Traditional Concept Of Scripting 207
13.6	Scripts And Programs 208
13.7	Stand-Alone Management Scripts 209
13.8	CLI, The Unix Expect Program, And Expect Scripts 210
13.9	Example Expect Script 211
13.10	Management Scripts, Homogeneity, And Expect 212
13.11	An Example Stand-Alone Script With Graphical Output 214
13.12	Using Scripts As An Extension Mechanism 223
13.13	Example Server With Scripting Extensions 223
13.14	Example Of Server Extension Points 225
13.15	Script Interface Functionality 226
13.16	Example Server Extension Script 227
13.17	Example Script That Manipulates A Reply 230
13.18	Handling Multiple Tasks With A Single Script 232
13.19	Script Timing, External Access, And Overhead 233
13.20	Summary 234
	For Further Study 235

PART III The Future Of Network Management 237

Chapter 14 Network Automation: Questions And Goals 239

14.1	Introduction 239
14.2	Network Automation 240
14.3	Dividing The Problem By Network Type 241
14.4	Shortcomings Of Existing Automation Tools 242
14.5	Incremental Automation Vs. A Blank Slate 243
14.6	Interface Paradigm And Efficiency 244
14.7	The Goal Of An Automated Management System 246
14.8	Desiderata For An Automated Management System 248
14.9	Multiple Sites And Managers 250
14.10	Authority Domains And Role-Based Access Control 250
14.11	Focus On Services 251
14.12	Policies, Constraints, And Business Rules 251
14.13	Correlation Of Multiple Events 253
14.14	Mapping From Logical To Physical Locations 253
14.15	Autonomy, Manual Override, And Policy Changes 254
14.16	Summary 255

Chapter 15 Architectures For Network Management Software 257

15.1	Introduction 257
15.2	Paradigms For Management System Design 258
15.3	Characteristics Of A Top-Down Approach 258
15.4	Characteristics Of A Bottom-Up Approach 259
15.5	Selecting Any Or All In A Bottom-Up Design 260
15.6	Weaknesses of The Two Design Paradigms 260
15.7	A Hybrid Design Methodology 261
15.8	The Critical Need For Fundamental Abstractions 262
15.9	An Analogy To Operating Systems 263
15.10	Separation Of Management From Elements 264
15.11	Mapping From Abstractions To Network Elements 264
15.12	Northbound And Southbound Interfaces 265
15.13	A Set Of Architectural Approaches 266
	15.13.1	Monolithic Architecture 266
	15.13.2	Extensible Framework 268
	15.13.3	Software Backplane 268
	15.13.4	Tiered Hierarchy 270
	15.13.5	Database-Centric 272
15.14	Useful Implementation Techniques 273
15.15	Late Binding Of A Programmatic Interface 275
15.16	Validation Of External Expectations 276
15.17	An Architecture Of Orthogonal Tools 278
15.18	Summary 279

Chapter 16 Representation, Semantics, And Information Models 283

16.1	Introduction 283
16.2	Data For Management Software 283
16.3	The Issue Of Data Representation 284
16.4	Internal Representation And Programming Language 286
16.5	The Effect Of Programming Paradigm On Representation 286
16.6	Objects And Object-Based Representation 287
16.7	Object Representation And Class Hierarchy 288
16.8	Persistence, Relations, And Database Representation 288
16.9	Representations At Various Points And Times 289
16.10	Translation Among Representations 290
16.11	Heterogeneity And Network Transmission 291
16.12	Serialization And Extensibility 292
16.13	The Need For Semantic Specification 293
16.14	Semantic Validity And Global Inconsistency 293
16.15	Information Models And Model-Driven Design 294
16.16	Information And Data Models 295
16.17	Class Hierarchies In An Object-Oriented Model 296
16.18	Multiple Hierarchies 298
16.19	Hierarchy Design And Efficiency 299
16.20	Cross-Hierarchy Relationships And Associations 300
16.21	Prescriptive Models And Generality 301
16.22	Purpose Of Models And Semantic Inference 303
16.23	Standardized Information Models 303
16.24	Graphical Representation Of Models (UML) 304
16.25	The Issue Of Complexity 306
16.26	Mapping Objects To Databases And Relations 307
16.27	Representation And Storage Of Topology Information 307
16.28	Ontology And Data Mining 309
16.29	Summary 309

Chapter 17 Design Tradeoffs 313

17.1	Introduction 313
17.2	Tradeoffs Involving Scope And Overall Approach 313
17.3	Architectural Tradeoffs 315
17.4	Engineering Tradeoffs And Costs 317
17.5	Tradeoffs In Representation And Semantics 318
17.6	Summary 321

Chapter 18 Open Questions And Research Problems 323

18.1	Introduction 323
18.2	Fundamental Abstractions For A Management System 323
18.3	Separation Of Control And Validation 324
18.4	Boundary Between A Network And End Systems 324
18.5	Taxonomy Of Network Management Architectures 325
18.6	Extent Of Functionality Offered By Existing Systems 325
18.7	Management Of Routing And Traffic Engineering 325
18.8	Automated Address Assignment 325
18.9	Analysis Of Routing 326
18.10	Security Policy Enforcement 326
18.11	Infrastructure Redesign For Automated Management 326
18.12	Peer-To-Peer Propagation Of Management Information 327
18.13	Routing Failure Analysis 327
18.14	Limits Of Automated Topology Discovery 327
18.15	Data Mining Of NetFlow Data 327
18.16	Storage Of Network State 328
18.17	Anomaly Detection Using Bayesian Filtering 328
18.18	Cost Of Protection In Scripting 328
18.19	Late-Binding Interface Management Applications 328
18.20	Boundary Between Management System And Elements 329
18.21	Summary 329

Table of Contents For

Network Management Systems

Preface xv

Chapter 1 The Network Management Challenge 1

PART I Basics And Definitions 9

Chapter 2 A Review Of Network Elements And Services 11

Chapter 3 The Network Management Problem 25

Chapter 4 Configuration And Operation 39

Chapter 5 Fault Detection And Correction 55

Chapter 6 Accounting And Billing 67

Chapter 7 Performance Assessment And Optimization 77

Chapter 8 Security 97

PART II Tools And Platforms 115

Chapter 9 Management Tools And Technologies 117

Chapter 10 Simple Network Management Protocol (SNMP) 143

Chapter 11 Flow Data And Flow Analysis (NetFlow) 163

Chapter 12 Routing And Traffic Engineering 185

Chapter 13 Management Scripting 205

PART III The Future Of Network Management 237

Chapter 14 Network Automation: Questions And Goals 239

Chapter 15 Architectures For Network Management Software 257

Chapter 16 Representation, Semantics, And Information Models 283

Chapter 17 Design Tradeoffs 313

Chapter 18 Open Questions And Research Problems 323

Bibliography 331

Index 335

Table of Contents For Network Management Systems

Preface xv

Chapter 1 The Network Management Challenge 1

PART I Basics And Definitions 9

Chapter 2 A Review Of Network Elements And Services 11

Chapter 3 The Network Management Problem 25

Chapter 4 Configuration And Operation 39

Chapter 5 Fault Detection And Correction 55

Chapter 6 Accounting And Billing 67

Chapter 7 Performance Assessment And Optimization 77

Chapter 8 Security 97

PART II Tools And Platforms 115

Chapter 9 Management Tools And Technologies 117

Chapter 10 Simple Network Management Protocol (SNMP) 143

Chapter 11 Flow Data And Flow Analysis (NetFlow) 163

Chapter 12 Routing And Traffic Engineering 185

Chapter 13 Management Scripting 205

PART III The Future Of Network Management 237

Chapter 14 Network Automation: Questions And Goals 239

Chapter 15 Architectures For Network Management Software 257

Chapter 16 Representation, Semantics, And Information Models 283

Chapter 17 Design Tradeoffs 313

Chapter 18 Open Questions And Research Problems 323

Bibliography 331

Index 335

Table of Contents For

Network Management Systems