Product Documentation

Content Switching

Nov 03, 2016

  • I have installed a non-NetScaler load balancing appliance on the network. However, I would like to use the content switching feature of the NetScaler appliance to direct the client requests to the load balancing appliance. Is it possible to use the Content switching feature of the NetScaler appliance with a non-NetScaler load balancing appliance?

    Yes. You can use the Content switching feature of the NetScaler appliance with the load balancing feature of the NetScaler appliance or a non-NetScaler load balancing appliance. However, when using the non-NetScaler load balancing appliance, make sure that you create a load balancing virtual server on the NetScaler appliance and bind it to the non-NetScaler load balancing appliance as a service.

  • How is a Content switching virtual server different from a load balancing virtual server?

    A Content switching virtual server is capable only of sending the client requests to other virtual servers. It does not communicate with the servers.

    A Load balancing virtual server balances the client load among servers and communicates with the servers. It monitors server availability and can be used to apply different load balancing algorithms to distribute the traffic load.

    Content switching is a method used to direct client requests for specific types of content to targeted servers by way of load balancing virtual servers. You can direct the client requests to the servers best suited to handle them. This result in reduced overheads to process the client requests on the servers.

  • I want to implement the Content switching feature of the NetScaler appliance to direct the client requests. What types of client request can I direct by using the Content switching feature?

    You can direct only HTTP, HTTPS, FTP, TCP, Secure TCP, and RTSP client requests by using the Content switching feature. To direct HTTPS client requests, you must configure the SSL offload feature on the appliance.

  • I want to create Content switching rules on the NetScaler appliance. What are the various elements of the client request on which I can create a content switching rule?

    You can create the content switching rules based on the following elements and their values in the client request:

    • URL
    • URL tokens
    • HTTP version
    • HTTP Headers
    • Source IP address of the client
    • Client version
    • Destination TCP port
  • I understand that the content switching feature of the NetScaler appliance helps enhance the performance of the network. Is this correct?

    Yes. You can direct the client requests you the servers best suited to handle them. The result is reduced overhead for processing the client requests on the servers.

  • Which feature of the NetScaler appliance should I configure on the NetScaler appliance to enhance the site manageability and response time to the client requests?

    You can configure the content switching feature of the NetScaler appliance to enhance the site manageability and response time to the client request. This feature enables you to create content groups within the same domain name and IP address. This approach is flexible, unlike the common approach of explicitly partitioning the content into different domain names and IP addresses, which are visible to the user.

    Multiple partitions dividing a Web site into various domain names and IP addresses force the browser to create a separate connection for each domain it finds when rendering and fetching the content of a web page. These additional WAN connections degrade the response time for the web page.

  • I have hosted a web site on a web server farm. What advantages does the NetScaler content switching feature offer for this type of setup?

    The content switching feature provides the following advantages on a NetScaler appliance in a site that is based in a web server farm:

    • Manage the site content by creating a content group within the same domain and IP address.
    • Enhance the response time to client requests by using the content group within the same domain and IP address.
    • Avoid the need for full content replication across domains.
    • Enable application-specific content partitioning. For example, you can direct client requests to a server that handles only dynamic content or only static content, as appropriate for the request.
    • Support multi-homing of multiple domains on the same server and use the same IP address.
    • Reuse connections to the servers.
  • I want to implement the content switching feature on the NetScaler appliance. I want to direct the client requests to the various servers after evaluating the various parameters of each request. What approach should I follow to implement this setup when configuring the content switching feature?

    You can use policy expressions to create policies for the content switching feature. An expression is a condition evaluated by comparing the qualifiers of the client request to an operand by using an operator. You can use the following parameters of the client request to create an expression:

    • Method- HTTP request method.
    • URL- URL in the HTTP header.
    • URL TOKENS- Special tokens in the URL.
    • VERSION- HTTP request version.
    • URL QUERY- Contains the URL Query LEN, URL LEN, and HTTP header.
    • SOURCEIP- IP address of the client.

    Following is a complete list of the operators that you can use to create an expression:

    • == (equals)
    • != (not equals)
    • EXISTS
    • NOT EXISTS
    • CONTAINS
    • NOT CONTAINS
    • GT (greater than)
    • LT (less than)
    You can also create various rules, which are logical aggregations of a set of expressions. You can combine multiple expressions to create rules. To combine expressions, you can use the && (AND) and   (OR) operators. You can also use parenthesis to create nested and complex rules.
  • I want to configure a rule based policy along with a URL based policy for the same content switching virtual server. Is it possible to create both types of policies for the same content switching virtual server?

    Yes. You can create both type of policies for the same content switching virtual server. However, be sure to assign priorities to set an appropriate precedence for the policies.

  • I want to create content switching policies that evaluate the domain name, along with a prefix and suffix of a URL, and direct the client requests accordingly. Which type of content switching policy should I create?

    You can create a Domain and Exact URL policy. When this type of policy is evaluated, the NetScaler appliance selects a content group if the complete domain name and the URL in the client request match the ones configured. The client request must match the configured domain name and exactly match the prefix and suffix of the URL if they are configured.

  • I want to create content switching policies that evaluate the domain name, along with a partial prefix and suffix of URL, and direct the client requests accordingly. Which type of content switching policy should I create?

    You can create a Domain and Wildcard URL policy for the content switching virtual server. When this type of policy is evaluated, the NetScaler appliance selects a content group if the request matches the complete domain name and partially matches the URL prefix.

  • What is a Wildcard URL policy?

    You can use wildcards to evaluate partial URLs in client requests to the URL you have configured on the NetScaler appliance. You can use wildcards in the following types of URL-based policies:

    • Prefix only. For example, the /sports/* expression matches all URLs available under the /sports URL. Similarly, the /sports* expression matches all URLs whose prefix is /sports .
    • Suffix only. For example the /*.jsp expression matches all URLs with a file extension of jsp.
    • Prefix and Suffix. For example, the /sports/*.jsp expression matches all URLs under the /sports/ URL that also have the jsp file extension. Similarly, the /sports*.jsp expression matches all URLs with a prefix of /sports* and a file extension of jsp.
  • What is a Domain and Rule policy?

    When you create a Domain and Rule policy, the client request must match the complete domain and the rule configured on the NetScaler appliance.

  • What is the default precedence set for evaluating policies?

    By default, the rule based policies are evaluated first.

  • If some of the content is the same for all client requests, what type of precedence should I use for evaluating policies?

    If some of the content is same for all the users and different content should be served on the basis of client attributes, you can use URL-based precedence for policy evaluation.

  • What policy expression syntaxes are supported in content switching?

    Content switching supports two types of policy expressions:

    • Classic Syntax- Classic syntax in content switching starts with the keyword REQ and is more advanced than the default syntax. Classic policies cannot be bound to an action. Therefore, the target load balancing virtual server can be added only after binding the content switching virtual server.
    • Default Syntax: Default syntax generally starts with key word HTTP and is easier to configure. A target load balancing virtual server action can be bound to a Default Syntax policy, and the policy can be used on multiple content switching virtual servers.
  • Can I create an action based policy using classic expressions?

    No. As of now NetScaler does not support policies using classic syntax expressions with actions. The target load balancing virtual server should be added when binding the policy instead of defining it in an action.