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Cluster General

Table of Contents

Load Balancer

Name | Type | Mode | Strategy

Session Management

Session Extraction | Session ID String | Session Timeout | Insert Tracking Cookie | Tracking Cookie Name

Custom Error Messages

Name

Description

A unique name for a cluster.

Type

Description

Specifies the type of cluster.

"Layer7" HTTP load balancing, also known as application-level load balancing, parses HTTP requests and distributes requests to servers based on different types of request contents.

"Layer4" load balancing is transport layer load balancing, such as TCP and UDP transport protocols. It does not look at the content when selecting a backend server. In theory, Layer 4 load balancing supports every application type.

Syntax

Select from drop down list

Mode

Description

Specifies which mode the load balancer operates in, "Stateless" or "Stateful".

"Stateful" mode track sessions associated with each back-end server. It also called "Session Affinity".

"Stateless" mode does not care about sessions.

For the Layer 4 Load Balancer, if the Mode is “Stateful”, it will track the IP address of the client to extract previous sessions.

Syntax

Select from drop down list

Strategy

Description

Select load balancing strategy from the list.

  • The round-robin algorithm cycles through a list of backend Server instances in order.
  • The least-load algorithm improves on the round-robin algorithm by taking into account current load for each server.
  • The least-session algorithm choose the server with fewest session associated.

Syntax

Select from drop down list

Session Extraction

Description

Specify how to extract session ID from request.

IP Address: Uses Client IP as session ID.

Basic Authentication: Uses username in the basic authentication as session ID.

Query String: Uses a Parameter in request query string as session ID.

Cookies: Uses a Parameter in cookie as session ID.

SSL Session: Uses SSL Session ID as session ID.

JVM Route: JVM Route is an extra section appended to a Servlet session ID, which used to identify servlet backend. Example: JSESSIONID=344BA8002DE6FBE2QDF25.tomcat1

URL Path Parameter: Uses a URL Path Parameter as session ID.

Syntax

Select from checkbox

Tips

For Layer 4 Load Balancers, only the IP Address extraction method will work. For Layer 7 Load Balancers, any of the above methods will work.

Session ID String

Description

Specifies the Session ID string. The string is used to extract the session id value from cookie, query string and URL path parameter.

Session Timeout

Description

Specify for how long a session will be valid, in seconds.

Syntax

Integer number

Insert Tracking Cookie

Description

Specify whether to insert a tracking cookie. The tracking cookie can be used to reconstruct session cache in case load balancer lost it.

Syntax

Select from radio box

Tracking Cookie Name

Description

Specify the tracking cookie name.

Syntax

string

Custom Error Messages

Description

Specify a custom error message in case error occured during distributing request to backend servers. Custom error messages configured at virtual host level will override this configuration.