Deliuery Networks. A Practical Guide to Content. Gilbert Held. Second Edition. CRC Press. Taylor & Francis Group

Transcription

1 A Practical Guide to Content Deliuery Networks Second Edition Gilbert Held CRC Press Taylor & Francis Group Boca Raton London NewYork CRC Press is an imprint of the Taylor & Francis Croup, an informa business AN AUERBACH BOOK

2 Contents Preface Acknowledgments xiii xvii Chapter 1 Introduction to Content Delivery Networking Hie Modern Content Delivery Network Advantages Disadvantages Evolution Client-Server Computing Client-to-Mainframe Data Flow Modern Client-Server Operations Use of Video Servers Video Length Video Resolution Frame Rate Color Depth Data Compression Server NetworkArchitecture Two-Tier Architecture Three-Tier Architecture Tie Road to Push Technology Teletext Systems Videotext Pull Technology Role of Caching Pull Limitations 22 V

3 VI CONTENTS Multicast Advantages Addresses Limitations Push Technology Evolution Crawling Feeds Advantages S Disadvantages Content Delivery Networking Client-Server Operations on the Internet Client Server Operating on the Same Network Client-Server Operations on Different Networks Peering Point Video Considerations 38 Client-Server Models Overview Client Operations URLs Absolute and Relative Shortening URLs HTML Versions HTML Documents Font Control Hypertext Links Adding Images Adding Video HTTP Versions Operation HTTP State Maintenance Browser Programs Helpers Plug-Ins Java VBScript ActiveX Server Operations Evolution Common Web Server Programs Server Characteristics 71

4 CONTENTS VII Application Servers Access Java Application Servers General Server Tools Microsoft's.NET Framework Distance Relationship Using Ping Using Traceroot 80 Chapter 3 Understanding TCP/IP The TCP/IP Protocol Suite Protocol Suite Components Physical and Data-Link Layers MAC Addressing Layer 3 Addressing ARP The Network Layer IP Header The Transport Layer TCP UDP Port Meanings The Domain Name System Need for Address Resolution Domain Name Servers Top-Level Domain DNS Operation Configuring Your Computer Root Name Servers The NSLookup Tool Expediting the Name Resolution Process DNS Resource Records SOAResource Record Name Server (NS) Records Address (A) records Host Information (HINFO) Record Mail Exchange (MX) Canonical Name (CNAME) Records 105 Records Other Records 105 Chapter 4 The CDN Model Why Performance Matters Economics of Poor Performance Predictability Customer Loyalty Scalability 111

5 CONTENTS 4.1.S Flexibility Company Perception Summary Examining Internet Bottlenecks Entry and Egress Considerations Access Delays Egress Delays Benefits of Edge Servers Peering Points Rationale Peering and Transit Operations Transit and Peering Operations Global Structure of Peering Points Representative Peering Points Peering Point Delays 144 Edge Operations CDN Operation The Akamai Network Type of Content Support Centralized Web Site Access Edge Server Model Limitations Edge Side Includes ESI Support Inclusion and Conditional Inclusion Environmental Variables Exception and Error Handling Language Tags Tne ESI Template Edge Side Includes for Java Statistics Summary The Akamai HD Network Using the HD Network with Flash Selecting the Client Population Selecting Bit Rates Selecting Frame Sizes Profiles Levels Keyframes 165 Caching and Load Balancing Caching Browser Cache Other Types ofweb Caches Proxy Caches Gateway Caches Server Caches 173

6 CONTENTS IX Application Caching Cache Operation Cache Control Methods META Tags HTTP Headers Cache-Control Header Directive Application Cache-Request Directives Cache-Response Directives Windows DNS Caching Problems Viewing HTTP Headers Considering Authentication Enhancing Cacheability Load Balancing Types ofload Balancing Rationale Load Balancing Techniques DNS Load Balancing Load Balancing Methods Hardware versus Software DNS Load Balancing DNS Load-Sharing Methods Using CNAMES UsingA Records Managing User Requests Hidden Fields Settings URL Rewriting 203 The CDN Enterprise Model Overview Rationale Concentrated Customer Base Distributed Locations Available for Use Knowledgeable Staff Control Economics Summary Traffic Analysis Using Web Logs Apache Access Logs Access Records HTTP Response Codes Using Logging Strings Web-Log Analysis Top Referring Domains 217

7 X CONTENTS Considering Status Codes Web-Log Statistics Reverse Mapping SOA Record Components Origination Country 22^ Originating Time Zone Other Statistics Other Analysis Tools 22« Cookies Cookie Basics Writing Cookies How a Cookie Moves Data How Web Sites Use Cookies Problems with Cookies Other Logging Information Microsoft's Performance Monitor Activating Performance Monitor Adding Counters and Instances Working with Performance Monitor Summary Using a Network Analyzer Other Tools to Consider Content Delivery Models Single-Site, Single-Server Model Advantages Disadvantages Considering Server Options Considering Network Operations Single-Site, Multiple-Server Model Advantages Disadvantages Multiple-Sites, Single-Server per Site Model Advantages Disadvantages Multiple-Site, Multiple-Server per Site Model Advantages Disadvantages An In-Between Model 257 Chapter 7 Web-Hosting Options 7.1 Rationale Cost Elements and Total Cost Performance Elements Server-Side Language Support Web-Service Tools Hie Importance of Images 266

8 CONTENTS XI Back-End Database Support Facility Location(s) Types of Web-Hosting Facilities Dedicated Hosting Shared Server Hosting Colocated Hosting Evaluation Factors 273 Index 277