Using OOB code
1. stop the JSP engine

3. restart the JSP engine

This setting will add an HTTP response header to certain responses, 'ARRESPONSEHOSTIP', which will be the IP address of the responding Mid-tier machine, e.g.:

HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
ARRESPONSEHOSTIP: 172.29.84.38
Cache-Control: public,max-age=86400
Expires: Fri, 06 Aug 2010 16:37:18 GMT
...

An HTTP tracing utility, like FiddlerTool or the native Network Capture functionality of the browsers, can show these raw HTTP responses.

NOTE: The IP address should not change during the user's session; if it does, the user may see ARERR 9201 or 9351 errors.

Using the DebugFilterServlet (attached) for midtier 9.1.03 or lower
To get an ARRESPONSEHOSTIP  and JVMID header on every response, use the DebugFilterServlet
There is a INSTALL.txt file included in the zip, but here are the basic install instructions:
 
1)            Stop the web application engine (Tomcat, for example)
2)            Copy the 'DebugServletFilter.jar' into your web app's /WEB-INF/lib directory
3)           Backup the original 'web.xml' file (in /WEB-INF) to 'web.xml.bak' (for example)
4)            Add the following <filter> and <filter-mapping> elements to your web.xml file (place it among the other <filter> elements), and start the web application engine
 
                <filter>
                                <filter-name>DebugServletFilter</filter-name>
                                <filter-class>com.bmc.support.util.filter.DebugServletFilter</filter-class>
                                <init-param>
                                                <param-name>addresponsehostip</param-name>
                                                <param-value>true</param-value> <!-- *** Set this to 'false' to disable *** -->
                                </init-param>
                                <init-param>
                                                <param-name>jvmid</param-name>
                                                <param-value>midtier_1</param-value> <!-- *** Set this to a unique value for each Mid-Tier instance *** -->
                                </init-param>                  
                </filter>
                <filter-mapping>
                                <filter-name>DebugServletFilter</filter-name>
                                <url-pattern>/*</url-pattern>
                </filter-mapping>                          
 
(NOTE: Use a unique "jvmid" in the web.xml entry for each instance of web application server (physical or clustered), for example:midtier_1, midtier_2, midtier_3)
 

5. Do a hard cache flush while your JSP Engine is stopped

Deleting the content of the <Mid Tier install Directory>/cache directory
Deleting the <Tomcat Installation Directory>/work/Catalina/localhost/arsys/ directory.

6. Restart the JSP engine
7. Clear your browser cache
When you clear your IE browser cache, please make sure that you have not checked the "Preserve Favorite website data" option as this will keep the Mid Tier pages cached in your browser and defeat the purpose of clearing your browser cache for this issue.
8. Retest the issue with Fiddler tools running to check the the ARRESPONSEHOSTIP  and JVMID parameters are now displayed in BackChannel lines as well as FORM request lines.

RESPONSEHOSTIP: 123.45.67.890
JVMID: midtier_1

Using the DebugFilter for midtier 9.1.04 or betterer
To get an ARRESPONSEHOSTIP  and JVMID header on every response, use the DebugFilter
 
1)            Stop the web application engine (Tomcat, for example)
2)            Backup the original 'web.xml' file (in /WEB-INF) to 'web.xml.bak' (for example)
3)            Uncomment the following <filter> and <filter-mapping> elements in your web.xml file
 
                <filter>
                                <filter-name>DebugFilter</filter-name>
                                <filter-class>com.remedy.arsys.stubs.DebugFilter</filter-class>
                                <init-param>
                                                <param-name>addresponsehostip</param-name>
                                                <param-value>true</param-value> <!-- *** Set this to 'false' to disable *** -->
                                </init-param>
                                <init-param>
                                                <param-name>jvmid</param-name>
                                                <param-value>midtier_1</param-value> <!-- *** Set this to a unique value for each Mid-Tier instance *** -->
                                </init-param>                  
                </filter>
                <filter-mapping>
                                <filter-name>DebugFilter</filter-name>
                                <url-pattern>/*</url-pattern>
                </filter-mapping>                          
 
(NOTE: Use a unique "jvmid" in the web.xml entry for each instance of web application server (physical or clustered), for example:midtier_1, midtier_2, midtier_3)

4. Do a hard cache flush while your JSP Engine is stopped

Deleting the content of the <Mid Tier install Directory>/cache directory
Deleting the <Tomcat Installation Directory>/work/Catalina/localhost/arsys/ directory.

5. Restart the JSP engine
6. Clear your browser cache
When you clear your IE browser cache, please make sure that you have not checked the "Preserve Favorite website data" option as this will keep the Mid Tier pages cached in your browser and defeat the purpose of clearing your browser cache for this issue.
7. Retest the issue with Fiddler tools running to check the the ARRESPONSEHOSTIP  and JVMID parameters are now displayed in BackChannel lines as well as FORM request lines.

RESPONSEHOSTIP: 123.45.67.890
JVMID: midtier_1