Design your networks to successfully manage their growing complexity     Network professionals have often been told that today’s modern control planes would simplify their networks. The opposite has happened: Technologies like SDN and NFV, although immensely valuable, are exacerbating complexity instead of solving it. Navigating Network Complexity is the first comprehensive guide to managing this complexity in both deployment and day-to-day operations.   Russ White and Jeff Tantsura introduce modern complexity theory from the standpoint of the working network engineer, helping you apply it to the practical problems you face every day. Avoiding complex mathematical models, they show how to characterize network complexity, so you can understand it and control it.   The authors examine specific techniques and technologies associated with network control planes, including SDNs, fast reroute, segment routing, service chaining, and cloud computing. They reveal how each of these affects network design and complexity and help you anticipate causes of failure in highly complex systems.   Next, they turn to modern control planes, examining the fundamental operating principles of SDNs, such as OpenFlow and I2RS, network and other service function virtualization, content distribution networks, Layer 2 fabrics, and service chaining solutions. You’ll learn how each of these might both resolve and increase complexity in network design and operations and what you can do about it.   Coverage includes:   Defining complexity, understanding its components, and measuring it Mastering a straightforward “state, speed, and surface” model for analyzing complexity Controlling complexity in design, deployment, operations, protocols, and programmable networks Understanding how complex network systems begin to fail and how to prevent failure Recognizing complexity tradeoffs in service virtualization and service chaining Managing new challenges of complexity in virtualized and cloud environments Learning why constructs such as hierarchical design, aggregation, and protocol layering work and when they work best Choosing the right models to contain complexity as your network changes   From start to finish, Navigating Network Complexity helps you assess the true impact of new network technologies, so they can capture more value with fewer problems.  

Table of Contents:
Introduction . . . . . . . . . . . . xvii     How This Book Is Organized . . . . . . . xvii Chapter 1: Defining Complexity . . . . . . . . . 1     What Is Complexity? . . . . . . . . . 3         Anything I Don’t Understand . . . . . . 3         Anything with a Lot of Parts . . . . . . . 5         Anything for Which There Is More State Than Required to         Achieve a Goal . . . . . . . . . 9         Unintended Consequences . . . . . . 11     Why So Much Complexity? . . . . . . . . 13         Future Extensions versus New Protocols . . . . 16         Unexpected Errors . . . . . . . . 17     Why Not Build Infinitely Complex Systems? . . . . . 18         Quick, Cheap, and High Quality: Choose Two . . . 20         Consistency, Availability, and Partition Tolerance:         Choose Two . . . . . . . . . 21     Journey into the Center of Complexity . . . . . . 22 Chapter 2: Components of Complexity . . . . . . . 25     Network Convergence . . . . . . . . . 26         Path Vector: A BGP Example . . . . . . 26         Distance Vector: An EIGRP Example . . . . . 28         Link State: OSPF and IS-IS Convergence . . . . 30     State . . . . . . . . . . . . 31         Amount of Information . . . . . . . 32         An Example of State Failure in the Real World . . . 33         Final Thoughts on State . . . . . . . 34     Speed . . . . . . . . . . . . 35         The Network That Never Converges . . . . . 35         The Flapping Link . . . . . . . . 37         Final Thoughts on Speed . . . . . . . 38     Surface . . . . . . . . . . . . 38     The Hourglass Model . . . . . . . . . 41     Optimization . . . . . . . . . . . 44     A Final Thought . . . . . . . . . . 46 Chapter 3: Measuring Network Complexity . . . . . . 47     Some Measures of Network Complexity . . . . . 49         Network Complexity Index . . . . . . 49         Modeling Design Complexity . . . . . . 51         NetComplex . . . . . . . . . 53     Organized Complexity . . . . . . . . . 55     Is This a Waste of Time? . . . . . . . . . 58         A Final Thought . . . . . . . . . . 58 Chapter 4: Operational Complexity . . . . . . . . 61     Exploring the Problem Space . . . . . . . . 61         The Cost of Human Interaction with the System . . . 61         Policy Dispersion versus Optimal Traffic Handling . . 66     Solving the Management Complexity Problem . . . . 69         Automation as a Solution to Management Complexity . 69         Modularity as a Solution to Management Complexity . 72         Protocol Complexity versus Management Complexity . 74         A Final Thought . . . . . . . . . . 77 Chapter 5: Design Complexity . . . . . . . . . 79     Control Plane State versus Stretch . . . . . . . 81         Aggregation versus Stretch . . . . . . . 83         Traffic Engineering . . . . . . . . 85         State versus Stretch: Some Final Thoughts . . . . 87     Topology versus Speed of Convergence . . . . . . 88         Ring Topology Convergence . . . . . . 88         Redundancy versus Resilience . . . . . . 90         Topology versus Speed of Convergence:         Some Final Thoughts . . . . . . . 93     Fast Convergence versus Complexity . . . . . . 94         Improving Convergence with Intelligent Timers: Talk Faster . . . . . . . . . 96         Removing Timers from Convergence: Precompute . . 99         Working around Topology: Tunneling to the Loop-Free         Alternate . . . . . . . . . 101         Some Final Thoughts on Fast Convergence . . . 104     Virtualization versus Design Complexity . . . . . 106         Functional Separation . . . . . . . 108         Forwarding Plane Complexity . . . . . . 109         Control Plane Complexity . . . . . . 109         Shared Fate Risk Groups . . . . . . . 111     A Final Thought . . . . . . . . . . 111 Chapter 6: Managing Design Complexity . . . . . . 113     Modularity . . . . . . . . . . . 113         Uniformity . . . . . . . . . 114         Interchangeable Modules . . . . . . . 120         How Modularity Attacks the Complexity Problem . . 121     Information Hiding . . . . . . . . . 122         Aggregation . . . . . . . . . 122         Failure Domains and Information Hiding . . . . 126         Final Thoughts on Information Hiding . . . . 128     Models . . . . . . . . . . . 129         Waterfall . . . . . . . . . . 129         Places in the Network . . . . . . . 131         Hierarchical . . . . . . . . . 132         UML . . . . . . . . . . . 134     A Final Thought . . . . . . . . . . 136 Chapter 7: Protocol Complexity . . . . . . . . 137     Flexibility versus Complexity: OSPF versus IS-IS . . . . 138     Layering versus Protocol Complexity . . . . . . 141         The Seven-Layer Model . . . . . . . 143         The Four-Layer Model . . . . . . . 146         The Iterative Model . . . . . . . . 147         Protocol Stacks and Design . . . . . . 148     Protocol Complexity versus Design Complexity . . . . 149         Microloops and Fast Reroute . . . . . . 149         EIGRP and the Design Conundrum . . . . . 158     Final Thoughts on Protocol Complexity . . . . . 162 Chapter 8: How Complex Systems Fail . . . . . . . 163     Feedback Loops . . . . . . . . . . 164         Positive Feedback Loops in Network Engineering . . 169         Speed, State, and Surface: Stability in the         Network Control Plane . . . . . . . 174     Shared Fate . . . . . . . . . . . 177         Virtual Circuits . . . . . . . . . 177         TCP Synchronization as a Shared Fate Problem . . 179     A Final Thought . . . . . . . . . . 181         Thoughts on Root Cause Analysis . . . . . 181         Engineering Skills and Failure Management . . . 182 Chapter 9: Programmable Networks . . . . . . . 185     Drivers and Definition . . . . . . . . . 186         Business Drivers . . . . . . . . 186         The Ebb and Flow of Centralization . . . . . 188         Defining Network Programmability . . . . . 191     Use Cases for Programmable Networks . . . . . 193         Bandwidth Calendaring . . . . . . . 193         Software-Defined Perimeter . . . . . . 196     Programmable Network Interfaces . . . . . . 200     The Programmable Network Landscape . . . . . 201         OpenFlow . . . . . . . . . . 202         YANG . . . . . . . . . . 204         Path Computation Element Protocol . . . . . 207         Interface to the Routing System . . . . . 210     A Final Thought . . . . . . . . . . 212 Chapter 10: Programmable Network Complexity . . . . . 215     The Subsidiarity Principle . . . . . . . . 216     Policy Management . . . . . . . . . 217         Policy Dispersion . . . . . . . . 220         Policy Consistency . . . . . . . . 222         Policy Complexity . . . . . . . . 223     Surface and the Programmable Network . . . . . 224     Impact on Failure Domains . . . . . . . . 226         Wide Area Failure Domains . . . . . . 227         Data Center Failure Domains . . . . . . 228         Application to Control Plane Failure Domain . . . 229         Controller to Controller Failure Domain . . . . 229         Final Thoughts on Failure Domains . . . . . 229     A Final Thought . . . . . . . . . . 230 Chapter 11: Service Virtualization and Service Chaining . . . . 233     Network Function Virtualization . . . . . . . 234         NFV: A Use Case . . . . . . . . 236     Service Chaining . . . . . . . . . . 242         Service Function Chaining . . . . . . 243         Segment Routing . . . . . . . . 245     A Final Thought . . . . . . . . . . 248 Chapter 12: Virtualization and Complexity . . . . . . 249     Policy Dispersion and Network Virtualization . . . . 250         State and Service Chaining . . . . . . 253         State and Optimization . . . . . . . 254         Surface and Policy Interaction . . . . . . 255         Surface and Policy Proxies . . . . . . 255     Other Design Considerations . . . . . . . 256         Coupling and Failure Domains . . . . . . 257         Troubleshooting . . . . . . . . 260     The Orchestration Effect . . . . . . . . 262     Managing Complexity . . . . . . . . . 264     A Final Thought . . . . . . . . . . 266 Chapter 13: Complexity and the Cloud . . . . . . . 267     Where Does the Complexity Live? . . . . . . 268         Cloud Centric . . . . . . . . . 269         Vendor Centric . . . . . . . . . 270         Network Centric . . . . . . . . 271         Is There a “Right Way?” . . . . . . . 271     Centralize What? . . . . . . . . . . 272     Cloudy Complications . . . . . . . . . 273         Security . . . . . . . . . . 273         Data Portability . . . . . . . . 276     A Final Thought . . . . . . . . . . 277 Chapter 14: A Simple Ending . . . . . . . . . 279     Defining Complexity . . . . . . . . . 279         Difficult to Understand . . . . . . . 280         Unintended Consequences . . . . . . 280         Large Numbers of Interacting Parts . . . . . 280         What Makes Something “Too Complex”? . . . 281     Complexity Is a Tradeoff . . . . . . . . 282     Modeling Complexity . . . . . . . . . 284     Managing Complexity in the Real World . . . . . 286         Don’t Ignore Complexity . . . . . . . 286         Find a Model to Contain the Complexity . . . . 287     A Final Thought . . . . . . . . 288 TOC, 9780133989359, 10/28/2015