Optimization :55:22 UTC Citrix Systems, Inc. All rights reserved. Terms of Use Trademarks Privacy Statement

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1 Optimization :55:22 UTC 2015 Citrix Systems, Inc. All rights reserved. Terms of Use Trademarks Privacy Statement

2 Contents Optimization... 5 Optimization... 6 Client Keep-Alive... 8 Configuring Client Keep-Alive Enabling or Disabling Client Keep-Alive Globally Enabling or Disabling Client Keep-Alive for a Service Configuring Connection Options with HTTP Profiles Compression Enabling or Disabling Compression Enabling and Disabling Compression for a Service Configuring Compression Actions Configuring Compression Policies Bind Points and Order of Evaluation for Default Syntax Compression Policies... Bind Points and Order of Evaluation for Classic Compression Policies Creating Policy Labels Binding Compression Policies Globally Binding Compression Policies to Virtual Servers Setting Global Compression Parameters Configuring Compression for a Load Balancing Virtual Server Viewing Compression Statistics by Using the Dashboard Viewing Compression Statistics by Using SNMP Viewing Additional Compression Statistics Integrated Caching How the Integrated Cache Works Example of Dynamic Caching Setting Up the Integrated Cache Installing the Integrated Cache License Enabling or Disabling Integrated Cache

3 Configuring Global Attributes for Caching Built-in Content Group, Pattern Set, and Policies for the Integrated Cache... Configuring Selectors and Basic Content Groups Advantages of Selectors Using Parameters Instead of Selectors Configuring a Selector About Content Groups Setting Up a Basic Content Group Expiring or Flushing Cached Objects Expiring a Content Group Manually Configuring Periodic Expiration of a Content Group Configuring Policies for Caching and Invalidation Actions to Associate with Integrated Caching Policies Bind Points for a Policy Configuring a Policy in the Integrated Cache Globally Binding an Integrated Caching Policy Binding an Integrated Caching Policy to a Virtual Server Example: Caching Compressed and Uncompressed Versions of a File 92 Configuring a Policy Bank for Caching Configuring a Policy Label in the Integrated Cache Unbinding and Deleting an Integrated Caching Policy and Policy Label 101 Caching Support for Database Protocols Configuring Expressions for Caching Policies and Selectors Expression Syntax Configuring an Expression in a Caching Policy or a Selector Displaying Cached Objects and Cache Statistics Viewing Cached Objects Finding Particular Cached Responses Viewing Cache Statistics Improving Cache Performance Reducing Flash Crowds Caching a Response after a Client Halts a Download Setting a Minimum Number of Server Hits Prior to Caching Example of Performance Optimization Configuring Cookies, Headers, and Polling Divergence of Cache Behavior from the Standards Removing Cookies from a Response

4 Inserting HTTP Headers at Response Time Ignoring Cache-Control and Pragma Headers in Requests Polling the Origin Server Every Time a Request Is Received Configuring the Integrated Cache as a Forward Proxy Example of an Integrated Caching Configuration Default Settings for the Integrated Cache Default Caching Policies Initial Settings for the Default Content Group TCP Buffering Enabling or Disabling TCP Buffering Globally Enabling or Disabling TCP Buffering for a Service Setting TCP Buffering Parameters TCP Keep-Alive Configuring Keep-Alive in TCP Profiles

5 Optimization The NetScaler optimization features reduce transaction times between the clients and the servers, and they reduce bandwidth consumption. They also enhance server performance by offloading some tasks and making others more efficient. This collection includes the following topics: Client keep-alive Compression Integrated Caching TCP-Buffering TCP keep-alive Handles multiple requests on a single client connection. The client does not have to negotiate a new connection for each request to the server. Compresses HTTP responses sent from the servers to compression-aware browsers. The smaller responses reduce download time and save bandwidth. Stores responses to client requests. Subsequent requests for the same content are served from the NetScaler cache instead of being forwarded to the origin server. Buffers the server's response and sends it to the client at the client's speed. The server can quickly offload the requested data and then devote its resources to other tasks. Sends TCP keep-alive probes to check the operational state of the peer. 5

6 Client Keep-Alive The Citrix NetScaler appliance provides features such as client keep-alive to improve the performance of a transaction management environment. Performance of any transaction management environment depends on factors such as bandwidth usage, download time, speed of the server and the client networks, and time consumed to complete a transaction. Client keep-alive improves performance by reducing the time consumed in a transaction. Two other settings that affect connection management include the maximum number of HTTP connections retained in the connection reuse pool and whether or not connection multiplexing is enabled. These variables are configured with HTTP profiles. Client keep-alive enables multiple client requests to be sent on a single client connection. This feature helps in a transaction management environment where the server closes the client connection after serving the response to the client. The client has to open a new connection for each request to the server leading to a lot of time being consumed for a transaction. The client keep-alive feature of the appliance alleviates this problem by keeping the client-side connection open between the client and the appliance even after the server closes the client connection. This allows multiple client requests to be sent using a single connection. Keeping the client-side connection open saves the packet round trips associated with opening and closing a connection. This is most beneficial to SSL sessions because this eliminates unnecessary termination and open sequences, thus reducing the time taken for a transaction to occur. Client keep-alive is useful under either of the following conditions: When the server does not support client keep-alive. When the server supports client keep-alive but an application on the server does not support client keep-alive. Client keep-alive can be applied to all HTTP services globally, or to a specific service, such as HTTP or SSL. Note that client keep-alive applies only to HTTP and HTTPS services. The following figure illustrates a typical client keep-alive deployment. 6

7 Optimization Figure 1. Client Keep-Alive Entity Model As shown in the figure, to configure client keep-alive, you need to define services and enable client keep-alive for those services. Services represent applications on physical servers. The traffic from the client is intercepted by the configured service and the client request is directed to the origin server. The server sends the response and closes the connection between the server and the appliance. If a Connection: Close header is sent, this header is corrupted in the client-side response, and the client-side connection is kept open. As a result, the client does not have to open a new connection for the next request; instead, the connection to the server is reopened. Note: If a server sends back two Connection: Close headers, only one is edited. This results in significant delays on the client rendering of the object because a client does not assume that the object has been delivered completely until the connection is actually closed. 7

8 Client Keep-Alive The Citrix NetScaler appliance provides features such as client keep-alive to improve the performance of a transaction management environment. Performance of any transaction management environment depends on factors such as bandwidth usage, download time, speed of the server and the client networks, and time consumed to complete a transaction. Client keep-alive improves performance by reducing the time consumed in a transaction. Two other settings that affect connection management include the maximum number of HTTP connections retained in the connection reuse pool and whether or not connection multiplexing is enabled. These variables are configured with HTTP profiles. Client keep-alive enables multiple client requests to be sent on a single client connection. This feature helps in a transaction management environment where the server closes the client connection after serving the response to the client. The client has to open a new connection for each request to the server leading to a lot of time being consumed for a transaction. The client keep-alive feature of the appliance alleviates this problem by keeping the client-side connection open between the client and the appliance even after the server closes the client connection. This allows multiple client requests to be sent using a single connection. Keeping the client-side connection open saves the packet round trips associated with opening and closing a connection. This is most beneficial to SSL sessions because this eliminates unnecessary termination and open sequences, thus reducing the time taken for a transaction to occur. Client keep-alive is useful under either of the following conditions: When the server does not support client keep-alive. When the server supports client keep-alive but an application on the server does not support client keep-alive. Client keep-alive can be applied to all HTTP services globally, or to a specific service, such as HTTP or SSL. Note that client keep-alive applies only to HTTP and HTTPS services. The following figure illustrates a typical client keep-alive deployment. 8

9 Client Keep-Alive Figure 1. Client Keep-Alive Entity Model As shown in the figure, to configure client keep-alive, you need to define services and enable client keep-alive for those services. Services represent applications on physical servers. The traffic from the client is intercepted by the configured service and the client request is directed to the origin server. The server sends the response and closes the connection between the server and the appliance. If a Connection: Close header is sent, this header is corrupted in the client-side response, and the client-side connection is kept open. As a result, the client does not have to open a new connection for the next request; instead, the connection to the server is reopened. Note: If a server sends back two Connection: Close headers, only one is edited. This results in significant delays on the client rendering of the object because a client does not assume that the object has been delivered completely until the connection is actually closed. 9

10 Configuring Client Keep-Alive To configure the client keep-alive feature, you need to create a service and enable client keep-alive for that service. The service you configure enables the NetScaler appliance to keep the client-side connection open even after the server has closed the connection between the server and the appliance. Note that while configuring a service, if the client keep-alive option is not explicitly specified, the service uses the global setting for the client keep-alive connection. For more information, see "Enabling or Disabling Client Keep-Alive Globally." To create a service with client keep-alive enabled by using the command line interface At the command prompt, type: add service (<name> <IPaddress>) <servicetype> <port> -CKA (YES NO) Example > add service Service-HTTP HTTP 80 -CKA YES To create a service with client keep-alive enabled by using the configuration utility 1. In the navigation pane, expand Load Balancing, and then click Services. 2. In the details pane, click Add. 3. In the Create Service dialog box, amongst other service-related configurations, in the Advanced tab, under Settings, select Override Global and then select Client Keep-Alive. 4. Click Create, and then click Close. 10

11 Configuring Client Keep-Alive Parameter Descriptions (of commands listed in the CLI procedure) add service CKA The state of the Client Keep-Alive feature for the service. Possible values: YES, NO View description(s) in command reference Top 11

12 Enabling or Disabling Client Keep-Alive Globally The client keep-alive feature is disabled by default. If you enable client keep-alive globally, all new services inherit the global settings by default. The following procedure describes the steps to enable or disable client keep-alive globally. To enable or disable the client keep-alive mode globally by using the command line interface At the command prompt, type one of the following commands: enable ns mode cka disable ns mode cka To enable or disable the client keep-alive mode globally by using the configuration utility 1. Navigate to System > Settings. 2. In the details pane, under Modes and Features, click Configure modes. 3. In the Configure Modes dialog box, select or clear the Client Keep-Alive check box. 4. Click OK. Parameter Descriptions (of commands listed in the CLI procedure) enable ns mode No parameters provided in this topic or the command has no parameters. View description(s) in command reference Top disable ns mode No parameters provided in this topic or the command has no parameters. View description(s) in command reference Top 12

13 Enabling or Disabling Client Keep-Alive for a Service You can enable or disable client keep-alive at the service level. Note that the service level settings take precedence over the global settings. The following procedure describes the steps to enable or disable client keep-alive at the service level. To enable or disable the client keep-alive mode for a service by using the command line interface At the command prompt, type: set service (<name> <IPaddress>) -CKA (YES NO) Example > set service Service-HTTP-1 -CKA YES To enable or disable the client keep-alive mode for a service by using the configuration utility 1. In the navigation pane, expand Load Balancing, and then click Services. 2. In the details pane, click the service for which you want to enable or disable client keep-alive, and then click Open. 3. In the Configure Service dialog box, on the Advanced tab, under Settings, select or clear the Client Keep-Alive check box. 4. Click OK. Parameter Descriptions (of commands listed in the CLI procedure) set service name The name of the service. 13

14 Enabling or Disabling Client Keep-Alive for a Service IPaddress The new IP address of the service. CKA The state of the Client Keep-Alive feature for the service. Possible values: YES, NO View description(s) in command reference Top 14

15 Configuring Connection Options with HTTP Profiles An HTTP profile is a collection of configuration settings that is used to control HTTP requests to and responses from virtual servers on a NetScaler appliance. You can use HTTP profiles to configure the maximum number of HTTP connections retained in the connection reuse pool. You can also use HTTP profiles to enable connection multiplexing if you are not sure that it is already enabled ( By default, connection multiplexing is enabled.), and to enable Persistence ETag. When Persistent ETag is enabled, the ETag header includes information about the server that served the content. This ensures that cache validation conditional requests or browser requests, for that content, always reaches the same server. By default, Persistent ETag is disabled. For more information about HTTP profiles, see "Configuring HTTP Profiles." To configure the number of connections in the reuse pool by using the command line interface At the command prompt, type: set ns httpprofile <name> -maxreusepool <value> To configure the number of connections in the reuse pool by using the configuration utility 1. Navigate to System > Profiles. 2. In the details pane, on the HTTP Profiles tab, select the HTTP profile for which you want to configure the number of connections, and then click Open. 3. In the Configure HTTP Profiles dialog box, in Max connections in reusepool, specify the maximum number of connections you want to allow in connection reuse pool. 4. Click OK. To enable connection multiplexing by using the command line interface At the command prompt, type: 15

16 Configuring Connection Options with HTTP Profiles set ns httpprofile <name> -conmultiplex ENABLED To enable connection multiplexing by using the configuration utility 1. Navigate to System > Profiles. 2. In the details pane, on the HTTP Profiles tab, select the HTTP profile for which you want to enable connection multiplexing, and then click Open. 3. In the Configure HTTP Profiles dialog box, select the Connection Multiplexing check box. Note that this check box is enabled by default. 4. Click OK. To enable Persistent ETag by using the command line interface At the command prompt, type: set ns httpprofile <name> -persistentetag enabled To enable Persistent ETag by using the configuration utility 1. Navigate to System > Profiles. 2. In the details pane, on the HTTP Profiles tab, select the HTTP profile for which you want to enable Persistent Etag, and then click Open. 3. In the Configure HTTP Profiles dialog box, select the Persistent ETag option. By default, this option is disabled. Parameter Descriptions (of commands listed in the CLI procedure) set ns httpprofile maxreusepool Maximum connections in reusepool. If set to zero, limit will not be applied. Maximum value: conmultiplex 16

17 Configuring Connection Options with HTTP Profiles Connection multiplexing Possible values: ENABLED, DISABLED Default value: ENABLED persistentetag Generate the persistent NetScaler specific ETag for the HTTP response with ETag header. Possible values: ENABLED, DISABLED Default value: DISABLED View description(s) in command reference Top 17

18 Compression The Citrix NetScaler appliance compression feature compresses the size of HTTP responses sent from servers to compression-aware browsers and thereby improves the performance of Web sites by reducing the download time of Web content. Bandwidth is also saved in the process. Another indirect benefit of HTTP compression is that the data passed between the Web server and the browser is encrypted by virtue of the compression algorithm, adding more security to the data. After you enable the compression feature and compression is set at the service level, global compression policies are enabled, and the NetScaler can compress data for traffic that matches these policies. You can augment the built-in compression policies by creating new compression actions and policies and binding the policies globally or to particular virtual servers. When you bind a policy globally, you specify a bind point, which corresponds to a step in the sequence in which traffic is processed. Policies bound to a virtual server have their own place in the sequence. Therefore, binding the policies affects the order in which they are evaluated. Alternatively, you can associate policies with policy labels that are not associated with a bind point. Such policies can be invoked only by other policies. You can view statistics for compressed data that the NetScaler transmits. Note: The compression feature uses both classic and default syntax policies. This content is best understood if you are familiar with configuration principles for basic policies, virtual servers, and services. For more information about policies, see "Policies and Expressions." For more information about virtual servers and services, see "Creating a Virtual Server" and "Configuring Services." The NetScaler can compress HTML and other content that is generated statically or dynamically, including MIME types such as text/html, text/plain, text/xml, text/css, text/rtf, application/msword, application/vnd.ms-excel, and application/vnd.ms-powerpoint. After you enable the compression feature on the NetScaler and set compression ON for HTTP and SSL services, built-in compression policies are applied to the HTTP and SSL services. You can disable compression on a particular service, and you can create custom compression policies and bind both the built-in and custom compression policies to a load balancing virtual server. 18

19 Enabling or Disabling Compression If you want the NetScaler appliance to compress data, enable the compression feature and set compression ON for the configured service. After enabling compression, the built-in compression policies are in effect, and compression is automatically enabled for any services that you create. If you want to use compression in a load balancing environment, you also enable the load balancing feature. To compress traffic that is sent over SSL, you also enable the SSL feature. To enable or disable compression, load balancing, and SSL by using the command line interface At the command prompt, type one of the following commands: enable ns feature cmp lb ssl disable ns feature cmp lb ssl To enable or disable compression, load balancing, and SSL by using the configuration utility 1. Navigate to System > Settings. 2. In the details pane, under the Modes and Features group, click Configure basic features. 3. In the Configure Basic Features dialog box, select the Compression check box to enable it; clear the check box to disable it. If appropriate, also select the Load Balancing and SSL Offloading check boxes. 4. Click OK, and click Yes in the Enable/Disable Feature(s)? message box. Parameter Descriptions (of commands listed in the CLI procedure) enable ns feature No parameters provided in this topic or the command has no parameters. View description(s) in command reference Top 19

20 Enabling or Disabling Compression disable ns feature No parameters provided in this topic or the command has no parameters. View description(s) in command reference Top 20

21 Enabling and Disabling Compression for a Service By default, if the compression feature is disabled, any new service that you create is disabled for compression and uses the built-in compression policies. If you create any services prior to enabling compression, you must manually enable compression for the service. You can disable or enable compression for HTTP and SSL services. Compression is in effect for a compression-enabled service once you bind the service to a virtual server. You can bind HTTP services to an HTTP load balancing vserver, and bind SSL services to an SSL load balancing virtual server. The protocol types must match. To create a compression-enabled service by using the command line interface At the command prompt, type: add service <name> <IPAddress> HTTP <portnumber> set service <name> -CMP YES Example > add service Service-HTTP HTTP 80 > set service Service-HTTP-1 -CMP YES To enable or disable service-level compression by using the configuration utility 1. In the navigation pane, expand Load Balancing, and then click Services. 2. In the details pane, on the Services tab, select the service for which you want to enable or disable compression, and then click Open. 3. In the Configure Service dialog box, on the Advanced tab, under Settings, select Override Global, and then select or clear the Compression check box. 4. Click OK, and then click Close. 21

22 Enabling and Disabling Compression for a Service Parameter Descriptions (of commands listed in the CLI procedure) add service set service No parameters provided in this topic or the command has no parameters. View description(s) in command reference Top CMP The state of the HTTP Compression feature for this service. Possible values: YES, NO View description(s) in command reference Top 22

23 Configuring Compression Actions You associate actions with compression policies. If an HTTP request matches the policy rule, the action is applied to the response. For example, you can configure a compression policy that identifies requests that are sent to a particular server, and associate the policy with an action that compresses data that is sent with the response. There are four built-in compression actions: COMPRESS: Uses the GZIP algorithm to compress data for browsers that support either GZIP or both GZIP and DEFLATE. The NetScaler appliance uses the DEFLATE algorithm to compress data for browsers that support the DEFLATE algorithm. If the browser does not support either algorithm, and the action has been set to COMPRESS, the NetScaler appliance does not compress data. NOCOMPRESS: Does not compress data. GZIP: Uses the GZIP algorithm to compress data for browsers that support GZIP compression. If the browser does not support the GZIP algorithm the NetScaler appliance does not compress data. DEFLATE: Uses the DEFLATE algorithm to compress data for browsers that support the DEFLATE algorithm. If the browser does not support the DEFLATE algorithm, and the action has been set to DEFLATE, the NetScaler appliance does not compress data. Compression actions determine whether and what type of compression the NetScaler appliance applies to a response. After creating an action, you associate the action with one or more compression policies. To create a compression action by using the command line interface At the command prompt, type: add cmp action <name> -cmptype (compress gzip deflate nocompress) 23

24 Configuring Compression Actions To create a compression action by using the configuration utility 1. In the navigation pane, expand HTTP Compression, and then click Actions. 2. In the details pane, click Add. 3. In the Create Compression Action dialog box, in the Name text box, type the name of the action (for example, Action-CMP-1). 4. Under Compression Type, choose the compression type (for example, GZIP). 5. Click Create, and then click Close. If you try to delete a built-in action, or any action that is associated with a policy, an error message appears. Only custom actions that have no associated policy can be deleted. Parameter Descriptions (of commands listed in the CLI procedure) add cmp action name The name of the compression action. cmptype The type of compression action. Possible values: compress, gzip, deflate, nocompress View description(s) in command reference Top 24

25 Configuring Compression Policies A compression policy contains a rule, which is a logical expression that enables the NetScaler appliance to identify the traffic that should be compressed. When the Citrix NetScaler appliance receives an HTTP response from a server, it evaluates a built-in or custom compression policy to determine whether to compress the response and the type of compression to apply. There are five built-in classic and advanced and default syntaxcompression policies. These policies are activated globally when you enable compression. The following table describes the built-in compression policies. Table 1. Built-in Classic and Advanced and Default Syntax Policies for Compression Built-in Classic and Advanced Compression Policies ns_nocmp_mozilla_47 ns_adv_nocmp_mozilla_47 ns_cmp_mscss ns_adv_cmp_mscss ns_cmp_msapp ns_adv_cmp_msapp Description Does not compress CSS files when a request is sent from a Mozilla 4.7 Web browser. Compresses CSS files when the request is sent from a Microsoft Internet Explorer Web browser. Compresses files that are generated by the following applications: Microsoft Office Word Microsoft Office Excel Microsoft Office PowerPoint ns_cmp_content_type ns_adv_cmp_content_type ns_nocmp_xml_ie ns_adv_nocmp_xml_ie Compresses data when the response contains the header 'Content-Type' and contains text. Does not compress when a request is sent from a Microsoft Internet Explorer browser with the response header 'Content-Type' and contains text or xml. To view built-in compression policies by using the configuration utility 1. In the navigation pane, expand HTTP Compression, and then click Policies. 2. In the details pane, view the built-in compression policies. 25

26 Configuring Compression Policies You can create a compression policy by using the built-in compression actions and named expressions, or you can use custom actions and expressions. To create a compression policy by using the command line interface At the command prompt, type: add cmp policy <name> -resaction (compress gzip deflate nocompress) -rule <build_in_rule_name> <user_defined_rule> Example > add cmp policy Policy-CMP-2 -resaction gzip -rule HTTP.REQ.HEADER( User-Agent ).CONTAINS( Mozilla/4. To create a compression policy by using the configuration utility 1. In the navigation pane, expand HTTP Compression, and then click Policies. 2. In the details pane, click Add. 3. In the Create Compression Policy dialog box, in the Policy Name text box, type the name of the policy. 4. In Response Action, do one of the following: To use a built-in or existing compression action, choose a compression action in the drop-down list. To create a new compression action, click New. In the Create Compression Action dialog box, enter a compression action name and type, and then click Create. 5. In the Expression box, either type the default syntax expression or do one of the following: Click Prefix, and then select the expression prefix you want. Then, select the flow type (REQ or RES), and then enter a period (.) to display a list of functions that can be used with the flow type. Type a period after each function until you have entered the expression you want. Click the Operators button to insert an operator (for example, a Boolean or relational operator). Click Add, and then select a named expression. 6. If you want to evaluate your expression, click Evaluate. 7. If you want to clear the Expression box, click Clear. 8. Click Create, and then click Close. You can modify the actions and expressions that are associated with a user-defined policy. However, you cannot make any modifications to the built-in compression policies. 26

27 Configuring Compression Policies You can remove a compression policy if the policy is not bound globally or to a vserver. If the compression policy is bound, you must first unbind it. You cannot remove a built-in compression policy. Parameter Descriptions (of commands listed in the CLI procedure) add cmp policy name The name of the HTTP compression policy to be created. resaction rule The compression action that needs to be performed when the rule matches. The string value can be either be a created compression action (user-defined) or one of the following built-in compression actions: NOCOMPRESS action - can be used to define a policy that disables compression for the matching policy.compress action - can be used to enable compression for a specific policy. This action will do GZIP or DEFLATE, based on the browser. GZIP action - can be used to enable GZIP compression for a specific policy. With this action, GZIP compression will be performed if the browser supports GZIP, other wise compression is disabled. DEFLATE action - can be used to enable DEFLATE compression for a specific policy. With this action, DEFLATE compression will be performed if the browser supports DEFLATE, otherwise compression is disabled. The rule associated with the HTTP compression policy. View description(s) in command reference Top 27

28 Bind Points and Order of Evaluation for Default Syntax Compression Policies For a default syntax policy to take effect, you must ensure that the policy is invoked at some point during the Citrix NetScaler appliance s processing of traffic. To specify the invocation time, you associate the policy with a bind point. The following are the built-in bind points, listed in order of evaluation: Request-time override. If a request matches a request-time override policy, by default request-time policy evaluation ends and the NetScaler appliance stores the action that is associated with the matching policy. Request-time load balancing virtual server. If policy evaluation cannot be completed after all the request-time override policies are evaluated, the NetScaler appliance processes request-time policies that are bound to load balancing virtual servers. If the request matches one of these policies, evaluation ends and the NetScaler appliance stores the action that is associated with the matching policy. Request-time content switching virtual server. Policies that are bound to this bind point are evaluated after request-time policies that are bound to load balancing virtual servers. Request-time default. If policy evaluation cannot be completed after all request-time, virtual server-specific policies are evaluated, the NetScaler appliance processes request-time default policies. If the request matches a request-time default policy, by default request-time policy evaluation ends and the NetScaler appliance stores the action that is associated with the matching policy. Response-time override. Similar to request-time override policy evaluation. Response-time load balancing virtual server. Similar to request-time virtual server policy evaluation. Response-time content switching virtual server. Similar to request-time virtual server policy evaluation. Response-time default. Similar to request-time default policy evaluation. You can associate multiple policies with each bind point. To control the order of evaluation of the policies associated with the bind point you configure a priority level. In the absence of any other flow control information, policies are evaluated according to priority level, starting with the lowest numeric priority value. You can also bind a given default syntax compression policy to more than one bind point. However, the bind point at which the policy is evaluated first is determined by the order specified in the preceding list. Assigned priority values must be unique within the collection of policies bound to a specific bind point. Additionally, for a given policy, only one binding is allowed per bind point at any given time. You should bind a policy with an INVAL action to a request-time override or a response-time override bind point. To delete a policy, you must first unbind it. 28

29 Bind Points and Order of Evaluation for Default Syntax Compression Policies Table 1. Entries to Control Evaluation Flow in a Policy Label Attribute Name Bound To Priority Goto Expression Specifies The name of the policy that you bound to the virtual server. The name of the virtual server to which the policy is bound. The priority level used to determine when the policy is evaluated relative to other policies that are bound to this virtual server. Specify an integer. The lower the integer, the higher the priority. Determines the next policy to evaluate in this label. Goto can proceed only forward in a policy label. Omitting the Goto expression is the same as specifying END. You can provide one of the following values: NEXT: Go to the policy with the next higher priority. END: Stop evaluation. USE_INVOCATION_RESULT: Applicable if this entry invokes another policy label. If the final Goto in the invoked bank has a value of END, evaluation stops. If the final Goto is anything other than END, the current policy label performs a NEXT. Positive number: Priority number of the next policy to be evaluated. Numeric expression: Expression that produces the priority number of the next policy to be evaluated. Flow Type Invoke Label Type You must specify a flow type to determine whether this policy is evaluated at request time or response time. Designates a policy label type. The value can be one of the following: Invoke Label Name Request Vserver: Invokes request-time policies that are associated with a virtual server. Response Vserver: Invokes response-time policies that are associated with a virtual server. Policy label: Invokes another policy label, as identified by the policy label for the bank. The name of a virtual server or a policy label, depending on the value that you specified for the invocation type. Finally, you can also bind compression policies to custom bind points bind points that you create. The bind points that you create are called policy labels. For more information about policy labels, see "Creating Policy Labels." 29

30 Bind Points and Order of Evaluation for Classic Compression Policies You can bind a classic compression policy either at the global level or at the virtual server (content switching or load balancing virtual server) level. You can also bind a given compression policy to more than one bind point. The priority values that are assigned to a policy that is bound to various bind points need not have the same value. For example, if you bind a policy called mycompressionpolicy both globally and to a load balancing virtual server, you can assign the policy a priority of 10 at the global bind point and a priority of 100 at the virtual server bind point. If you do not assign a policy a priority value, the NetScaler appliance assigns the classic compression policy a default priority value of 0 (zero). Therefore, the priorities assigned to the classic compression policies that are bound to various bind points at any given time might be an assortment of custom priority values and default values. During classic policy evaluation, priority values are considered first. The NetScaler appliance begins with the policy that has the lowest priority value (the default value of 0, if any, or the next higher custom priority value if none of the policies have a priority value of 0) regardless of the bind point to which the policy is bound. Then, the appliance evaluates policies in ascending order of priority values while moving from one bind point to the other if necessary. When the NetScaler appliance is evaluating policies based on their priority values, if multiple policies bound to different bind points happen to have the same priority value, the bind points of those policies are considered, with the order of evaluation progressing from the most specific bind point to the least specific bind point. For example, if classic policies are bound globally, to a content switching virtual server, and to a load balancing virtual server, the policies bound to the load balancing virtual server are evaluated first because, in this configuration, the load balancing virtual server represents the most specific bind point. The NetScaler appliance then evaluates the policies that are bound to the content switching virtual server. Finally, the appliance evaluates the policies that are bound at the global level (which is the least specific bind point in this configuration). Finally, at a given bind point, if two or more policies have the same priority value, the chronological order in which the policies were configured is considered. Among the policies that are bound to the same bind point, with the same priority value, the policy that was configured first is evaluated first, followed by the policy that was configured second, and so on. In this way, the NetScaler appliance evaluates classic policies based first on assigned priorities, then on bind points, and finally on the chronological order in which the policies were configured. 30

31 Creating Policy Labels You can create compression policy labels and configure banks of policies for these new labels. Policy labels can be considered as abstract bind points that you create. You can create policy labels only for advanced policies. The policies that are bound to a policy label can be evaluated by invoking the policy label from a policy that is bound to one of the following bind points: Request-time override Request-time default Response-time override Response-time default A virtual server You can invoke a policy label any number of times, unlike a policy which can only be invoked once. To create a policy label for compression by using the command line interface At the command prompt, type: add cmp policylabel <labelname> -type (REQ RES) 31

32 Creating Policy Labels To create a policy label for compression by using the configuration utility 1. In the navigation pane, expand HTTP Compression, and then click Policy Labels. 2. In the details pane, click Add. 3. In the Create Compression Policy Label dialog box, in Name, specify a name for the policy label. 4. In the Evaluates drop-down list, select whether the policy label will be evaluated at request time (REQ) or response time (RES). 5. Click Insert Policy, and then select the policy, or click New Policy to create a new policy. Note: To ensure that the NetScaler appliance processes the policy label at the right time, you can configure an invocation of this label from the policy labels that are associated with the built-in bind points. Select the appropriate policy label of request vserver from the Invoke column field. 6. Click Create, and then click Close. Note: You can use the NOPOLICY dummy policy to invoke any policy label from another policy label. The NOPOLICY entry is a placeholder that does not process a rule. Parameter Descriptions (of commands listed in the CLI procedure) add cmp policylabel labelname type The name of the HTTP compression policy label to be created. Specifies when policies bound to this policy label will be evaluated. Possible values: REQ, RES View description(s) in command reference Top 32

33 Binding Compression Policies Globally A global compression policy applies to all services that support compression. When binding the policy, you assign it a priority. The policy is enabled by default upon creation. To globally bind a compression policy by using the command line interface At the command prompt, type: bind cmp global <policyname> -priority <positiveinteger> -state (enabled disabled) To unbind a globally bound compression policy by using the command line interface At the command prompt, type: unbind cmp global <policyname> 33

34 Binding Compression Policies Globally To globally bind a compression policy by using the configuration utility 1. In the navigation pane, expand HTTP Compression, and then click Policies. 2. From the Action drop down list, select Policy Manager. 3. In the Compression Policy Manager dialog box, do one of the following: To bind compression policies by using classic expressions, perform the following: Click Switch to Classic Syntax on the top right corner of the page. Click Global. Click Insert Policy, and then click the policy name that you want to bind. Double-click the Priority field for the policy and set the priority. A lower value causes the policy to be evaluated before policies with a higher priority value. Click Apply Changes. Optionally, to configure an expression as described in "Binding Compression Policies Globally", double-click the field in the Expression column, and specify a valid expression. To bind compression policies by using advanced expressions, perform the following: Click Switch to Default Syntax on the top right corner of the page. Select a Request or Response bind point, and then select a second level of binding of either Override Global or Default Global. A list of policies appears. These are policies that are bound to this bind point. Click Insert Policy, and then click the policy name that you want to bind. Double-click the Priority field for the policy and set the priority. A lower value causes the policy to be evaluated before policies with a higher priority value. Specify other optional values, such as a Goto expression or invocation of an external policy label. To configure a Goto expression, double-click the field in the Goto Expression column, and enter valid priority level, the keywords NEXT or END, or an advanced expression. 4. Click Apply Changes, and then click Close. 34

35 Binding Compression Policies Globally Parameter Descriptions (of commands listed in the CLI procedure) bind cmp global No parameters provided in this topic or the command has no parameters. View description(s) in command reference Top unbind cmp global No parameters provided in this topic or the command has no parameters. View description(s) in command reference Top 35

36 Binding Compression Policies to Virtual Servers When you configure virtual server-based compression, you bind services and compression policies to a virtual server. This causes traffic that flows through a virtual server (to and from the bound services) to be subject to compression policies that you bind to the vserver. If you bind a policy to a vserver, the policy is evaluated only by compression-enabled services that are bound to this vserver. When binding a policy, you set a priority value. Policies with a lower priority value are evaluated before policies with a higher value. After unbinding a policy from a vserver, the policy ceases to act on the services associated with that vserver. To bind a compression policy to a load balancing vserver by using the command line interface At the command prompt, type: bind lb vserver <vservername> -policyname <policyname> -priority <positiveint> To bind a compression policy to a load balancing vserver by using the configuration utility 1. In the navigation pane, expand Load Balancing, and then click Virtual Servers. 2. In the details pane, click the name of the virtual server, and then click Open. 3. In the Configure Virtual Server (Load Balancing) dialog box, on the Policies tab, click Compression. 4. Click either Classic Expression or Advanced Expression. Click Insert Policy and select the policy that you want to bind. Optionally, you can double-click the Priority field and type a new priority level. To invoke another policy label or to configure a policy for a request vserver, from the Invoke drop-down list, make an appropriate selection. If you select a request vserver, you can bind a compression policy for the selected vserver by double-clicking the Invoke field. The Configure Compression Policies dialog box appears. 5. Click OK, and then click Close. 36

37 Binding Compression Policies to Virtual Servers Parameter Descriptions (of commands listed in the CLI procedure) bind lb vserver policyname The SureConnect/priority queuing/compression/appsecure/transform/filter/authorizati on/rewrite/responder/cache/syslog/nslog/tmtraffic policy that needs to be bound to the specified load balancing virtual server for SureConnect or priority queuing to be activated on a load balancing virtual server. View description(s) in command reference Top 37

38 Setting Global Compression Parameters You can customize the way the NetScaler appliance compresses data. To set global compression parameters by using the command line interface At the command prompt, type: set cmp parameter [-cmplevel <compressionlevel>] [-quantumsize <integer>] [-servercmp (ON OFF)] [-minressize <positiveinteger>] [-cmpbypasspct <positiveinteger>] [-cmponpush (ENABLED DISABLED)] [-policytype (CLASSIC ADVANCED)] To set global compression parameters by using the configuration utility 1. In the navigation pane, click HTTP Compression. 2. In the details pane, click Change compression settings. 3. In the Configure Compression Parameters dialog box, configure the settings (for example, set the Quantum size and Compression level), and then click OK. Parameter Descriptions (of commands listed in the CLI procedure) set cmp parameter cmplevel Compression level. Possible values: optimal, bestspeed, bestcompression Default value: NSCMPLVL_OPTIMAL quantumsize Minimum amount of data to compress as one unit. Default value: Minimum value: 8 Maximum value: servercmp Compression at back-end server. Possible values: ON, OFF Default value: ON minressize 38

39 Setting Global Compression Parameters Size of the smallest HTTP response that will be compressed. cmpbypasspct CPU usage (%) at which NetScaler should start progressively bypassing compression on HTTP requests. Default value: 100 Maximum value: 100 cmponpush Enable/disable compression on PUSH packet Possible values: ENABLED, DISABLED Default value: DISABLED policytype The type of the HTTP compression global policy bindings to be used for virtual servers that have no HTTP compression policies bound. Possible values: CLASSIC, ADVANCED Default value: NS_EXPR_TYPE_CLASSIC View description(s) in command reference Top 39

40 Configuring Compression for a Load Balancing Virtual Server When you configure virtual server-based compression, you bind services and compression policies to a virtual server. This causes traffic that flows through a virtual server to and from the bound services to be subject to compression policies that you bind to the vserver. When a client request flows through a vserver, compression policies identify whether the client can accept compressed data. The Citrix NetScaler appliance forwards the request to the destination server, as identified by a service that is bound to the load balancing vserver. After the NetScaler appliance receives the response from the server, it determines whether the response is compressible based on the compression policies that are bound to the virtual server. If the content is compressible, it is compressed and forwarded to the client. Task overview: configuring compression for a load balancing vserver. 1. Enable compression and load balancing, as described in "Enabling and Disabling Compression." 2. Add a vserver, as explained in Creating a Virtual Server" and Configuring an SSL-Based Virtual Server". 3. Add one or more HTTP or SSL services and bind the services to a vserver, as explained in "Creating a Service" and "Binding Services to the Virtual Server." 4. Create compression policies, as described in "Configuring Compression Policies." 5. Bind the compression policies to the vserver, as described in "Binding Compression Policies to Virtual Servers." 40

41 Viewing Compression Statistics by Using the Dashboard The Dashboard utility displays summary and detailed compression statistics in tabular and graphic format. Note: For more information about the statistics and charts, see the Dashboard help on the Citrix NetScaler appliance. To view compression statistics by using the Dashboard 1. In the Dashboard utility, in the Select Group list, choose Compression, and then do one or more of the following: To view of summary of compression statistics, click the Summary tab. To view compression statistics by protocol type, click the Details tab. To view the rate of requests processed by the compression feature, click the Chart tab. 41