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This chapter describes the Cisco Content Engine and considerations for configuring the Cache software.
Cisco Content Engines are the content distribution and delivery elements of a larger Cisco
Content Delivery Network (CDN) solution, which includes content routing, content switching, content delivery network management, and content services, as well as content distribution and delivery. The Content Engine solution addresses the need to distribute and receive high-bandwidth, media-rich content across the Internet or intranet without performance losses or content delivery delays.
Cisco Content Engines are installed strategically within your existing network to provide accelerated content delivery to the desktop user. To implement the Content Engines within your existing network, your network must support Cisco IOS software and the Web Cache Coordination Protocol (WCCP).
Cisco Content Engines accelerate content delivery and optimize bandwidth usage by transparently caching frequently accessed content and fulfilling content requests locally rather than traversing the Internet or intranet to a distant server farm each time a request is made.
Cisco Content Engines work with routers running Cisco IOS software and WCCP. WCCP redirects Hypertext Transfer Protocol (HTTP) traffic to a Content Engine; the Content Engine then manages the Web request.
For transparent processing of Web traffic, the Content Engine works in tandem with a router. This traffic includes user requests to view pages and graphics (objects) on World Wide Web servers, whether internal or external to your network, and the replies to those requests.
When a user requests an object from a Web server, the router first sends the request to a Content Engine. If the Content Engine has a copy of the requested object in storage, the Content Engine sends the user the object. Otherwise, the Content Engine gets the requested objects from the Web server, stores a copy of the objects (caches them), and simultaneously forwards the objects on to the user.
By caching Web objects in this manner, the Content Engine can speed the satisfaction of user requests if more than one user wants to access the same objects. This also reduces the amount of traffic between your network and the Internet, potentially improving your overall network performance and optimizing your bandwidth usage.
The Content Engine is configured with the command-line interface (CLI), or the Web-based management interface, which is a graphical user interface (GUI) accessed with a Web browser. Most configuration options can be made with the management interface, which also provides online help pages.
After you physically install the Content Engine hardware (refer to the Cisco Content Engine 500 Series Hardware Installation Guide), configure the software by performing the following tasks:
1. Collecting the Information Required for Initial Configuration
2. Initializing the Cache Software
3. Enabling and Disabling Cache Support on the Router
Step 2 Open a window for the Content Engine console using your terminal emulation program and power on the Content Engine.
When the Content Engine begins booting, it sends messages to the console window. After the operating system boots, you are ready to initialize the basic software configuration.
Step 3 Proceed to the next section, "Initializing the Cache Software."
To initialize the basic configuration after the operating system has booted, perform the following steps:
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Note The Cache software does not display ***** (asterisks) while you are verifying your admin password. |
---- System Configuration Dialog ----
You may use Ctrl-D to abort Configuration Dialog at any prompt.
Would you like to enter the initial configuration? [yes]: yes
host name: cache
domain name: cisco.com
admin password: test
cache IP address: 10.1.58.5
IP network mask: 255.255.255.0
gateway IP address: 10.1.58.1
DNS server: 172.16.2.132
Step 2 If the basic configuration is acceptable, enter yes. The Content Engine indicates whether the configuration is accepted. At this point, the basic configuration is finished.
Use this configuration? [yes]: yes
>> Building configuration...
>> . . START - phase complete
Once you have entered an acceptable basic configuration, the Content Engine displays the URL for the Web-based Content Engine management interface, for example, http://10.1.58.5:8001 (the default GUI server port is 8001).
Although the Content Engine with Cache software can function as a standalone proxy server and Web cache, it is mostly used with a router running the Web Cache Coordination Protocol (WCCP) to provide transparent proxy and caching services. When cache support is enabled on the router, and WCCP support enabled on the Content Engines, the devices can communicate and deliver the services for which they are configured. You can disable cache support on the router to suspend proxy and caching services, rather than turning off or otherwise disabling individual Content Engines. (Use the no ip wccp command on the router to disable caching.)
You must already know how to configure the router to make these configuration changes. If you do not know how to configure the router, consult the Cisco IOS documentation supplied with the router. Detailed information for the commands mentioned here is in the Cisco IOS documentation. See "Web Cache Communication Protocol Version 1," and "Web Cache Communication Protocol Version 2," for information on which Cisco IOS software release supports which version of WCCP on which platform.
To remove a Content Engine from a Content Engine cluster or from a WCCP environment without powering down, disable the running version of WCCP on the Content Engine by issuing the Cache software no wccp version 1 (or 2) command. The Content Engine will still service proxy-style requests and preserve its configuration settings.
router(config)# ip wccp enable
For example, to enable redirection, enter:
router(config-if)# ip web-cache redirect
You can confirm your settings using the following show commands on the router:
In global configuration mode, use the ip wccp command to enable cache support. For example, enter:
router(config)# ip wccp webcache
or
router(config)# ip wccp service-number
where service-number is the number of a predefined service (0 to 99).
For example, to enable redirection on port 80, enter:
router(config-if): ip web-cache redirect out
To enable redirection of HTTP traffic on port 80 and on another port, enter:
router(config-if): ip wccp 98 redirect out
You can confirm your settings using the following show commands on the router:
Once you have installed and configured the Content Engine and enabled caching on the router, check that the Cache software is working properly.
Step 2 From the CLI, enter the following to display the Content Engine HTTP caching saving statistics:
show statistics http savings
Step 3 Open a window for the Content Engine console using your terminal emulation program to connect to the home router or routers, and enter the show ip wccp web-cache command to display information about the Content Engine. The entry for the Content Engine should show a number greater than 0 for packets redirected. Also, check for hash assignments.
If the router shows that no packets are being redirected to the Content Engine, you must troubleshoot your setup.
You can manage the Content Engine with the CLI or the Content Engine management interface. To connect to the Content Engine management interface, perform the following steps:
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Note Be sure to enable Java, JavaScript, and Cascading Style Sheets on your Internet Explorer browser, or use the Netscape 4.0 or later browser. |
Step 2 Open the URL used in the basic Content Engine configuration, for example, http://10.1.58.5:8001.
You must include the port number in the URL (the default is 8001).You are prompted for a username and password. (See Figure 1-1.)
Step 3 Enter a correct username and password. The Content Engine returns the initial management page, which contains links to other management pages.
If you forget your password, you must have another administrator reset your password. The password for the user admin is specified in the basic system configuration dialog.
Refer to the Content Engine hardware documentation for instructions on physically removing a Content Engine from an active network.
The router and the Content Engine are in constant communication; thus, when the router notices that the engine is no longer responding to it, the router stops sending requests to the engine. This is transparent to users. If other Content Engines are attached to the router, the router continues sending requests to the other engines.
When you remove a Content Engine, the pages that were cached on the engine are no longer available to the router or other Content Engines. Thus, you might see an increase in outgoing Web traffic that might have otherwise been fulfilled by the engine you are removing. However, after a time, the router and other Content Engines will have redistributed the load of Web traffic.
If you remove the last Content Engine from a router, you can also disable cache support on the router. However, this is not necessary; having cache support enabled when there are no Content Engines attached has no effect on the router's performance.
To replace a Content Engine, remove the old engine from the network. Then, add the new engine and configure it using the same configuration parameters (IP address, and so forth) that you used for the removed engine.
Posted: Tue Jun 5 19:29:54 PDT 2001
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