Introducing Equalizer
Equalizer Installation and Administration Guide
21
The table below summarizes the basic capabilities of the cluster types supported by Equalizer.
Regardless of cluster type, Equalizer uses intelligent
load balancing
algorithms
to determine the best server to
receive a request. These algorithms take into account the configuration options set for the cluster and servers, real-
time server status information, and information from the request itself. For Layer 7 clusters, user-defined match
rules can also be used to determine the route a packet should take.
Load Balancing Configuration
When you configure a virtual cluster, you can select one of the following load-balancing algorithms to control how
Equalizer balances the load across your servers:
round robin
,
static weight
,
adaptive
,
fastest response
,
least
connections
,
server agent
, or
custom
.
When you configure the servers in a virtual cluster, you assign an
initial weight
between 0 and 200 for each server.
When you select one of the adaptive load-balancing algorithms (i.e., any algorithm other than round robin),
Equalizer uses the servers’ initial weights as a starting point to determine the percentage of requests to route to each
server. Each server handles a percentage of the total load based on its fraction of the total weights in the server
cluster. Equalizer dynamically adjusts server weights according to real-time conditions to ensure that Equalizer
routes requests to the server that is best able to respond. A server with a weight of zero (0) is considered down or
unavailable, and Equalizer does not route requests to servers in this state.
Real-Time Server Status Information
Equalizer gathers real-time information about a server’s status using ICMP Probes, TCP Probes, Active Content
Verification (
ACV)
, and Server Agents. ICMP and TCP Probes are the default probing methods.
Feature
Cluster Type
L4 UDP
L4 TCP
L7 HTTP
L7 HTTPS
Load balancing
policies
round robin, static weight, adaptive, fastest response,
least connections, server agent, custom
Server failure
detection (probes)
ICMP, TCP, Server
Agent
ICMP, TCP, ACV, Server Agent
Persistence
Based on IP
Using Cookies
Server selection by
request content
(i.e., Match Rules)
No; load is balanced according to
current load balancing policy.
Yes; load is balanced according to
decisions made by examining request
content.
Load balanced
protocols
Ideal for
stateless UDP-
based protocols,
such as DNS and
RADIUS; WAP
gateways; NFS
server clusters
that provide a
single-system
image.
Ideal for stateful
TCP-based
protocols, such
as HTTP, HTTPS,
SMTP, FTP,
LDAP/LDAPS
a
and others.
a. Note that some LDAP/LDAPS implementations are UDP-based.
HTTP
HTTPS
NAT and spoofing
Yes
Содержание E350GX
Страница 18: ...Chapter Preface 18 Equalizer Installation and Administration Guide ...
Страница 38: ...Chapter 1 Equalizer Overview 38 Equalizer Installation and Administration Guide ...
Страница 50: ...Chapter 2 Installing and Configuring Equalizer Hardware 50 Equalizer Installation and Administration Guide ...
Страница 62: ...Chapter 3 Using the Administration Interface 62 Equalizer Installation and Administration Guide ...
Страница 80: ...Chapter 4 Equalizer Network Configuration 80 Equalizer Installation and Administration Guide ...
Страница 110: ...Chapter 5 Configuring Equalizer Operation 110 Equalizer Installation and Administration Guide ...
Страница 208: ...Chapter 7 Monitoring Equalizer Operation 208 Equalizer Installation and Administration Guide ...
Страница 240: ...Chapter 8 Using Match Rules 238 Equalizer Installation and Administration Guide ...
Страница 258: ...Chapter 9 Administering GeoClusters 254 Equalizer Installation and Administration Guide Envoy Configuration Worksheet ...
Страница 262: ...Appendix A Server Agent Probes 258 Equalizer Installation and Administration Guide ...
Страница 274: ...Appendix B Timeout Configuration 270 Equalizer Installation and Administration Guide ...
Страница 280: ...Appendix D Regular Expression Format 276 Equalizer Installation and Administration Guide ...
Страница 296: ...Appendix E Using Certificates in HTTPS Clusters 292 Equalizer Installation and Administration Guide ...
Страница 310: ...Appendix F Equalizer VLB 306 Equalizer Installation and Administration Guide ...
Страница 318: ...Appendix G Troubleshooting 314 Equalizer Installation and Administration Guide ...