1. Setup a Load balancer such that it forwards requests to first middle tier only.
2. Make sure sticky bit is set on load balancer for session persistence (Check Load balancer documentation), You can Network level switch as well to send requests to multiple middle tier
3. Apply Prereq. patches (3175852, 3077386, 3209878)
4. Edit following entry in XML or Context File directly ($APPL_TOP/admin/$CONTEXT_NAME.xml) or via Oracle Application Manager
-- 4.1 "Web entry point Host" to the HTTP load-balancer machine name
-- 4.2 "Web entry point Domain" to the HTTP load-balancer domain name
-- 4.3 "Web entry protocol" to the HTTP load-balancer protocol e.g. "http" or "https"
-- 4.4 "Active Web Port" to the value of the HTTP load-balancer's external port
-- 4.5 "Login Page" to include "Web entry protocol"://"Web Host entry point"."Web domain entry point":"Active Web Port"
-- 4.6 "disco_machine" to load balancer machine
5. Run Autoconfig
6. Start Services & check if you can login to applications via Load balancer
7. Now clone this middle tier to another node (where you want to add another node)
8. Make sure above parameter are pointing to load balancer in second node as well
9. Change load balancer to point to second node only
10. shutdown services on first node
11. try accessing application from second node (you should be able to access application without issues)
11.1 -- If forms are not opening properly , check "ICX Form Launcher .." Profile option should point to load balancer
12. Now start application on both middle tier
13. Point load balancer to both middle tier
14. You should be able to access applications
Things to Note :
Above solution is for HTTP Layer load balancing & HTTP Server will forward Forms request to form server running on same node .
Metalink Note : 217368.1 Advanced Configurations and Topologies for Enterprise Deployments of E-Business Suite 11i