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Manual Chapter: Accelerating HTTP Traffic with an Asymmetric WebAccelerator System
Manual Chapter
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Overview: Accelerating HTTP traffic with an asymmetric WebAccelerator system

Operating asymmetrically, the BIG-IP® WebAccelerator™ system caches objects from origin web servers and delivers them directly to clients. The WebAccelerator system handles both static content and dynamic content, by processing HTTP responses, including objects referenced in the response, and then sending the included objects as a single object to the browser. This form of caching reduces server TCP and application processing, improves web page loading time, and reduces the need to regularly expand the number of web servers required to service an application.

Task summary for accelerating HTTP traffic with an asymmetric WebAccelerator system

Perform these tasks to accelerate HTTP traffic with an asymmetric WebAccelerator™ system.

Defining an NTP server

Network Time Protocol (NTP) synchronizes the clocks on a network by means of a defined NTP server.
  1. On the Main tab, click System > Configuration > Device > NTP . The NTP screen displays.
  2. Type an address for the NTP server in the Address field.
  3. Click Add.
  4. Click Update.
The NTP server is defined.

Creating an application profile for an asymmetric WebAccelerator system

An application profile provides the key information that the WebAccelerator™ system needs to appropriately handle requests to your site's web applications.
  1. On the Main tab, click WebAccelerator > Applications. The Applications List screen opens.
  2. Click Create.
  3. Name the application.
  4. In the Description field, type a description.
  5. From the Policy list, select a policy.
  6. In the Requested Host field, type each domain name (host name) that might appear in HTTP requests for your web application. The specified domain names are defined in the host map for the application profile.
  7. Click Save.
The application profile appears in the Application column on the Applications List screen.

Enabling the WebAccelerator system with the Web Acceleration profile

A WebAccelerator™ application must be available.
The Web Acceleration profile enables the WebAccelerator system by using WebAccelerator applications that run on a virtual server.
  1. On the Main tab, click Local Traffic > Profiles > Services > Web Acceleration . The Web Acceleration profile list screen opens.
  2. Click the name of a profile.
  3. Select the Custom check box. The fields in the Settings area become available for revision.
  4. For the WA Applications setting, select an application in the Available list and click Enable. The WebAccelerator application is listed in the Enabled list.
  5. Click Update.
The WebAccelerator system is enabled through the WebAccelerator application in the Web Acceleration profile.

Creating a pool to manage HTTP traffic

You can create a pool to manage HTTP connections.
  1. On the Main tab, click Local Traffic > Pools. The Pool List screen opens.
  2. Click Create. The New Pool screen opens.
  3. In the Name field, type a unique name for the pool.
  4. For the Health Monitors setting, from the Available list, select the http monitor, and click << to move the monitor to the Active list.
  5. From the Load Balancing Method list, select how the system distributes traffic to members of this pool. The default is Round Robin.
  6. For the Priority Group Activation setting, specify how to handle priority groups:
    • Select Disabled to disable priority groups. This is the default option.
    • Select Less than, and in theAvailable Members field, type the minimum number of members that must remain available in each priority group in order for traffic to remain confined to that group.
  7. Using the New Members setting, add each resource that you want to include in the pool:
    1. Type an IP address in the Address field, or select a node address from the Node List.
    2. Type 80 in the Service Port field, or select HTTP from the list.
    3. (Optional) Type a priority number in the Priority field.
    4. Click Add.
  8. Click Finished.
The new pool appears in the Pools list.

Creating a virtual server to manage HTTP traffic

You can create a virtual server to manage HTTP traffic as either a host virtual server or a network virtual server.
  1. On the Main tab, click Local Traffic > Virtual Servers . The Virtual Server List screen displays a list of existing virtual servers.
  2. Click the Create button. The New Virtual Server screen opens.
  3. In the Name field, type a unique name for the virtual server.
  4. For the Destination setting, in the Address field, type the IP address you want to use for the virtual server. The IP address you type must be available and not in the loopback network.
  5. In the Service Port field, type 80, or select HTTP from the list.
  6. From the HTTP Profile list, select http.
  7. From the Web Acceleration Profile list, select one of the following profiles with an enabled WebAccelerator application:
    • optimized-acceleration
    • optimized-caching
    • webacceleration
    • A customized profile
  8. In the Resources area of the screen, from the Default Pool list, select a pool name.
  9. Click Finished.
The HTTP virtual server appears in the list of existing virtual servers on the Virtual Server List screen.

Verifying an application profile

Verifying an application profile requires a personal computer (PC) that can run a web browser.
You must verify that the WebAccelerator™ system is able to properly send data to and receive data from the origin web servers.
  1. On a PC, open the hosts file to edit.
  2. Add the host name that you used to access the web site application. The host name must point to the IP address for the virtual server that you configured.
    Note: On Microsoft® Windows® 2000 and Windows® XP machines, the hosts file is located at: C:\WINDOWS\system32\drivers\etc\hosts.
    For example, if you can access the web site at the domain, and the virtual server is at IP address, add the following line to the hosts file on the machine running the browser: All network traffic from the web browser machine for the web site application subsequently goes to the virtual server.
  3. Request a page from the web site application. For example, if you configured, request a page from
    • If the browser times out the request, then the WebAccelerator system is not running, or the firewall is blocking access to port 80 on the WebAccelerator system.
    • If you receive an Access denied by intermediary error:
      • Verify that the hosts file is correct.
      • Verify that the host map for the application profile is correct.
      • Verify that you used a domain in the request that matches a requested host in the host map, and that it maps to the destination host.
    The page appears directly from the origin web servers.
  4. Remove any entries that you changed or added, once you verify the application profile and the host mapping.
The WebAccelerator system is verified to properly send data to and receive data from the origin web servers.

Implementation result

The WebAccelerator™ system is configured asymmetrically to accelerate HTTP traffic.

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