To install Agent on the oracle linux server
Go to Deployments TAB from 11g Grid control page
Click on Install Agent, then the below screen will be appeared
Click on the links which you want to perform, here I click on Fresh install
NOTE: If we want to upgrade agent from 10g to 11gr1 then simply click on Upgrade agent, so no need to install 11g agent on the server it will automatically install 11g and upgrade from 10g to 11g.
Fill all the fields according to the environment.
Here you need to know the Management Server Registration Password (OMS password) to continue.
Once done verify from the server : ./emctl status agent
Verify from grid control, it should show new oracle linux HOST
Run the .../agent11g/root.sh script (as root) as soon after installation is complete (or) you can check the "run root.sh" box if you have root access