Specifications

Chapter 6: Administering Virtual Clusters

70 Equalizer Installation and Administration Guide

routed to the same selected server for the entire session (while the cookie is valid -- see

cookie age, below).

• once only limits Equalizer to parsing headers (and executing match rules) for only the

first request of any client making multiple requests across a single TCP connection. This

option is on by default. If this option is turned off, then Equalizer will parse the headers

of every client request. See “Enabling the Once Only Flag for Persistent Connections” on

page 82.

11. For HTTP and HTTPS clusters, if you enable the persist flag, the following options appear in

the cluster parameters. Use these parameters to specify cookie behavior for the cluster:

• cookie age sets the time, in seconds, over which the client browser maintains the cookie

(0 means the cookie never expires). After the specified number of seconds have elapsed,

the browser can delete the cookie and any subsequent client requests will be handled by

Equalizer’s load-balancing algorithms.

• cookie generation is a value added to cookies when the cookie scheme is 2 or greater. In

order for cookies to be valid, cookie generation must match the equivalent number

embedded in the cookie. Conversely if you need to invalidate old cookies, increment this

number.

•cookie scheme (only displayed when the advanced flag is enabled) specifies the format

of the cookie to be used for the cluster as an integer between 0 and 2 (default is 2):

• cookie domain limits the presented cookie only to servers whose host name is within the

specified domain. For example, if the cookie domain is

coyotepoint.com, the browser

Note – Although it is permitted by the software, it is not recommended to define a Layer 7

cluster with persist and once only both turned off, and with no match rules. By defining a

Layer 7 cluster in such a way, you are essentially disabling Layer 7 processing, while still

incurring extra overhead for the Layer 7 cluster. If your application requires a cluster with no

persistence, header processing, or match rules, then we recommend that you define a

Layer 4 UDP or TCP cluster for the best performance.

Cookie Scheme Cookie Format

Constructs a cookie which will be named in such a way that so as

long as the cluster maintains the same IP address, servers can be

added to and removed from the cluster without invalidating all of the

existing cookies. This cookie stores the cluster IP and port, and

the server IP and port.

Constructs a cookie which will be valid across all clusters with the

same IP address (not port specific). A requirement for this to be

useful is that all clusters on that IP address share the same set of

servers. This cookie stores the Cluster IP, and Server IP and

port.

Constructs a cookie which will be valid across all clusters with the

same IP address (using any port), and the same server within those

clusters (with the server using any port). A requirement for this to

be useful is that all clusters on that IP address share the same set

of servers. This cookie encodes the Cluster IP and Server IP.