Troubleshooting the Cache Engine

This chapter covers some tasks that might help you resolve problems you might encounter with the Cache Engine. If you cannot resolve your problem using the Cache Engines' management interface, or with the information in this guide, please contact Cisco Technical Support for further help.

Determining Why the Cache Engine Cannot Connect to a Web Server

If the Cache Engine cannot reach a specific web server, try pinging the web server. If the Ping is unsuccessful, try tracing the route to the server. Look for loops in the route (where the packets are sent through the same set of routers continuously, so that the packets do not get outside a certain ring of routers).

If the Ping is unsuccessful, and there is a loop in the route, contact the owner of the looping router and tell them that they have a routing problem.

If the Ping is unsuccessful, but there is no loop in the route, then the web server is having a problem, or may no longer exist. Contact the owner of the web server, or wait until they find and fix the problem themselves.

If the Ping is successful, but you cannot connect to the web server using a web browser, then the web server may not be currently running on the target machine. Contact the owner of the web server, or wait until they find and fix the problem themselves.

You can also simply disable WCCP on the router, and see if you can then connect to the web server. If you still cannot make the connection, then the problem is not with the Cache Engines, but with the web server.

Determining Why Data is Not Being Cached

If the Status page for a Cache Engine shows that no data is being cached, you have not specifically turned off caching for the machine by removing it from the cache farm, and you know that the traffic you are testing with uses port 80, follow these steps to determine why the machine is not caching data:

Step 1 Use the show ip wccp EXEC command on the home router for the Cache Engine to determine whether the router is running WCCP. This command should also show the number of Cache Engines available to the router. If the router is not running the protocol, start it using the ip wccp command.

Step 2 Use the show ip interface EXEC command on the home router for the Cache Engine to determine whether the outbound interfaces are redirecting web packets to the cache farm. The output should show "Web Cache Redirect is enabled" for each outbound interface. If the interfaces do not have web cache redirection enabled, enable it for each interface using the ip web-cache redirect interface command.

Step 3 Use the show ip wccp web-caches command if the number of Cache Engines displayed in the show ip wccp command is less than expected. Any engines shown with this command should be fully configured and functional. If an engine is not listed, connect to that engine's management interface, click Config and go to the Basic option. Fix the configuration of the engine. Ensure you are using the correct IP addresses for the engine, its home router, and its gateway.

Step 4 If all configuration parameters appear to be correct, and the home router is running the required protocols, try rebooting the Cache Engine.

Step 5 If the Cache Engine is still not caching pages, contact Cisco Technical Support for assistance.

Determining Why Customized Pages Are Not Correct

Many web pages use cookies to customize the page for the user. If users complain that they are not getting correctly customized pages, this may indicate that the web server is not set up correctly to include the appropriate caching parameters in the HTTP header. You can try to convince the owner of the web server to address this issue, or you can turn off cookie caching in the cache farm. If you turn off cookie caching, only the HTML page that uses cookies is not cached.

To turn off cookie caching:

Step 1 Click Tuning and select the Freshness option; it controls cookie caching.

Step 2 Check No for Cache Cookies.

Step 3 Click UPDATE.

Obtaining Information for Technical Support

Use the TechSupport command to gather information that can help Cisco Technical Support personnel diagnose and resolve problems you might be having with your Cache Engine. The syntax of the TechSupport command is:

TechSupport

Command Environment

You can use the TechSupport command from the Cache Engine console or from a Telnet session. You cannot use the command when running from the recovery diskette.

Example

See "TechSupport" in "Console Command Reference," for an example of the command output.