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This chapter describes the Content Engine and Cache Engine (CE) and considerations for configuring the Cache software:
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Note For complete syntax and usage information for the commands and software referred to in this chapter, refer to the Cisco Cache Software Command Reference. |
Cisco CEs 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 CE 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 CEs are installed strategically within your existing network to provide accelerated content delivery to the desktop user. To implement the CEs within your existing network, your network must support Cisco IOS software and the Web Cache Communication Protocol (WCCP).
Cisco CEs 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 CEs work with routers running Cisco IOS software and WCCP. WCCP redirects Hypertext Transfer Protocol (HTTP) traffic to a CE; the CE then manages the web request.
For transparent processing of web traffic, the CE 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 CE. If the CE has a copy of the requested object in storage, the CE sends the user the object. Otherwise, the CE obtains 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 CE 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 CE 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.
The CE can also be configured to act as a content routing agent for a Content Router. The Cisco Content Routing Software Configuration Guide and Command Reference describes this content routing process. See the "Configuring the CE as a Content Routing Agent" section for details on configuring the CE as a content routing agent.
After you physically install the CE hardware, 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 CE.
When the CE 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 CE 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 CE displays the URL for the web-based CE management interface, for example, http://10.1.58.5:8001 (the default GUI server port is 8001).
Although the CE with Cache software can function as a standalone proxy server and web cache, it is mostly used with a router running the Web Cache Communication Protocol (WCCP) to provide transparent proxy and caching services. When cache support is enabled on the router, and WCCP support enabled on the CEs, 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 CEs. (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 CE from a CE cluster or from a WCCP environment without powering down, disable the running version of WCCP on the CE by issuing the Cache software no wccp version 1 (or 2) command. The CE 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).
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Note Use service number 99 to configure the CE as a reverse proxy, and
service number 98 to redirect HTTP traffic on a port other than port 80 to the CE. The CE
also supports services 90 through 97. See the CE WCCP global configuration commands in
Chapter 3 and Chapter 4 for CE configuration requirements. |
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 CE 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 CE HTTP caching saving statistics:
show statistics http savings
Step 3 Open a window for the CE 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 CE. The entry for the CE 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 CE, you must troubleshoot your setup.
You can manage the CE with the CLI or the CE management interface. To connect to the CE 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 CE 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 CE 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.
After you have configured domains on the Content Router, the next step is to configure each CE for each domain you want it to support as a content routing agent. To configure a CE as a content routing agent, perform the following steps.
First, prepare the CE for configuration:
Console(config)# http proxy outgoing exclude enable
Step 2 Enter the following command:
Console(config)# http proxy incoming 80
Step 3 Enter the following command:
Console(config)# boomerang dns enable
Next, perform the following steps for each of the domains you associated this CE with when you configured domains on the Content Router:
Console (config)# boomerang dns domain www.foo.com
After entering this command you are in domain configuration mode.
Step 2 Use the key keyword command to configure the same keyword for the CE that you configured for the Content Router. For example, if MyKeyword is the key entered on the Content Router for this domain, enter:
Console (config-domain)# key MyKeyword
Step 3 If the CE is not serving or caching the web content, use the content-server ip-address command to point to the external content source. For example:
Console (config-domain)# content-server 10.4.23.10
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Caution A CE running Cache software Release 2.5 cannot be used for transparent caching if it has been configured as a content routing agent. Therefore, if you want to use a CE for transparent caching, make sure that none of the boomerang commands are enabled on the CE. |
You can use Simple Network Management Protocol (SNMP) with the CE. SNMP is an application-layer protocol that provides a message format for communication between SNMP managers and agents. The SNMP agent gathers information about device parameters and network data from the Management Information Base (MIB). The agent and MIBs reside on the CE. The SNMP agent contains MIB variables whose values the SNMP manager can request. An agent can also send unsolicited messages, which are called traps, that alert the SNMP manager to a condition on the network. Traps can indicate improper user authentication, restarts, link status (up or down), or other significant events.
To configure SNMP on the CE, you define the relationship between the manager and the agent. You can do this by using the CE management interface. (See the "Logging On to the Management Interface" section.) From the System menu, choose SNMP to display the SNMP configuration page. Then, click the Help button to access details on using the SNMP configuration interface.
At a minimum, you need to enable SNMP and enter an SNMP community access string. The community string is text that acts like a password and gives the SNMP manager access to the SNMP agent.
To compile the Cisco CE MIB with your network management application, download the following files from the online SNMP Help page:
The following MIBs are supported by the Cisco Cache software:
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Note Because the Counter64 syntax is not supported in SNMP Version 1, you should use SNMP Version 2C with the Cisco Cache software MIB (CISCO-CACHEENGINE-MIB.my). |
Refer to the CE hardware documentation for instructions on physically removing a CE from an active network.
The router and the CE 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 CEs are attached to the router, the router continues sending requests to the other engines.
When you remove a CE, the pages that were cached on the engine are no longer available to the router or other CEs. 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 CEs will have redistributed the load of web traffic.
If you remove the last CE 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 CEs attached has no effect on router performance.
To replace a CE, 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: Wed Jun 6 20:50:39 PDT 2001
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