184 Citrix NetScaler Policy Configuration and Reference Guide
Where limit_identifier is a NetScaler function that indicates the type of traffic to
be monitored. For an example, see “Summary Examples of Advanced
Expressions and Policies,” on page 237. For more information on configuring
limit identifiers, see the Citrix NetScaler Traffic Management Guide.
This prefix can be used in any NetScaler feature that uses advanced policies and
expressions, such as Rewrite and Responder.
Configuring Policies That Control the Traffic Rate
For complete instructions on configuring rate-limiting policies, see the Citrix
NetScaler Traffic Management Guide. Following is an overview of configuring
policies to control the rate of traffic.
Task overview: Configuring policies to limit the amount of traffic
1. Optionally, configure a rate limit selector.
2. Configure a rate limit identifier, and if you have configured a rate limit
selector, include it in the rate limit identifier's definition. The rate limit
identifier assesses particular types of traffic for a user-configured time
interval, and returns a boolean TRUE if the amount of traffic exceeds a
user-configured limit within the time interval.
3. Configure an advanced policy that applies the rate limit identifier to
particular types of data, for example, to HTTP requests with particular IP
addresses or subnets to particular file types. The policy expression must be
a compound expression that contains at least two components:
• An expression that identifies traffic to which the rate limit identifier
is applied, for example:
http.req.url.contains("myAspx.aspx").
• An expression that identifies a rate limit identifier, for example:
sys.check_limit("myLimitIdentifier").
Following is a complete example of the policy rule:
http.req.url.contains("myAspx.aspx") &&
sys.check_limit("myLimitIdentifier")