Thanks a lot Bala for the quick reply.
Actually I have followed this link for my setup. All steps work fine. I am only stuck at Steps to install ESXi onto an iSCSI LUN via Software iSCSI .
The link says , iSCSI target lun will be listed as installation disk which needs to be chosen for installation. but in my case the iSCSI lun is not getting listed. however the previous step was successful. I was able to do successful login to iSCSI target lun from bios. That is something really strange. I am able to discover and login to iSCSI target lun from bios so why it is not getting listed as one of the installation disk??
Thanks again for all your help.