Tài liệu Load Balancing Servers, Firewalls, and Caches

Chapter 1: Introduction .1
The Need for load balancing 1
The Server Environment .1
The Network Environment .2
Load Balancing: Definition and Applications .3
LoadưBalancing Products 4
The Name Conundrum .5
How This Book Is Organized 5
Who Should Read This Book 6
Summary 6
Chapter 2: Server Load Balancing: Basic Concepts .7
Overview 7
Networking Fundamentals .7
Switching Primer 7
TCP Overview 8
Web Server Overview .9
The Server Farm with a Load Balancer .10
Basic Packet Flow in load balancing .12
Health Checks 14
Basic Health Checks .15
ApplicationưSpecific Health Checks 15
Application Dependency .16
Content Checks .16
Scripting 16
AgentưBased Checks 17
The Ultimate Health Check 17
NetworkưAddress Translation .18
Destination NAT .18
Source NAT 18
Reverse NAT 20
Enhanced NAT .21
PortưAddress Translation .21
Direct Server Return 22
Summary 24
Chapter 3: Server load balancing: Advanced Concepts .25
Session Persistence 25
Defining Session Persistence 25
Types of Session Persistence 27
Source IP–Based Persistence Methods .27
The Megaproxy Problem 30
Delayed Binding .32
Cookie Switching 34
CookieưSwitching Applications .37
CookieưSwitching Considerations .38
SSL Session ID Switching 38
Designing to Deal with Session Persistence .40
HTTP to HTTPS Transition 41
URL Switching 43
Separating Static and Dynamic Content .44
URL Switching Usage Guidelines 45
Summary 46
Chapter 4: Network Design with Load Balancers .47
The Load Balancer as a Layer 2 Switch versus a Router 47
Simple Designs 49
Designing for High Availability 51
Active–Standby Configuration .51
Active–Active Configuration 53
Stateful Failover 55
Multiple VIPs 56
LoadưBalancer Recovery .56
HighưAvailability Design Options .56
Communication between Load Balancers 63
Summary 63
Chapter 5: Global Server load balancing .64
The Need for GSLB .64
DNS Overview .65
DNS Concepts and Terminology 65
Local DNS Caching 67
Using Standard DNS for load balancing .67
HTTP Redirect .68
DNSưBased GSLB 68
Fitting the Load Balancer into the DNS Framework 68
Selecting the Best Site 72
Limitations of DNSưBased GSLB .79
GSLB Using Routing Protocols .80
Summary 82
Chapter 6: LoadưBalancing Firewalls 83
Firewall Concepts 83
The Need for Firewall load balancing .83
LoadưBalancing Firewalls .84
TrafficưFlow Analysis 84
LoadưDistribution Methods 86
Checking the Health of a Firewall 88
Understanding Network Design in Firewall load balancing 89
Firewall and LoadưBalancer Types 89
Network Design for Layer 3 Firewalls .90
Network Design for Layer 2 Firewalls .91
Advanced Firewall Concepts 91
Synchronized Firewalls .91
Firewalls Performing NAT .92
Addressing High Availability 93
Active–Standby versus Active–Active .93
Interaction between Routers and Load Balancers .94
Interaction between Load Balancers and Firewalls 95
Multizone Firewall load balancing 96
VPN load balancing .97
Summary 98
Chapter 7: LoadưBalancing Caches 99
Cache Definition 99
Cache Types .99
Cache Deployment .100
Forward Proxy 100
Transparent Proxy .101
Reverse Proxy .102
TransparentưReverse Proxy 103
Cache LoadưBalancing Methods .103
Stateless load balancing 104
Stateful load balancing 104
Optimizing load balancing for Caches 104
ContentưAware Cache Switching .106
Summary 107
Chapter 8: Application Examples .108
Enterprise Network 108
ContentưDistribution Networks .110
Enterprise CDNs .110
Content Provider .111
CDN Service Providers .112
Chapter 9: The Future of LoadưBalancing Technology .113
Server load balancing .113
The Load Balancer as a Security Device .113
Cache load balancing .114
SSL Acceleration .114
Summary 115
Appendix A: Standard Reference 116
References 117