Thanks for your reply! In fact I've checked "squid", it's a cache server more than a load balancer, I'll give more info about my applications and my concern:
1- Applications are based on PHP pages that query an Oracle DB and return results (No need to worry about the data of the DB, it will be replicated on both servers.) Cache servers will not be a good idea for me since data in the DB changes frequently.
2- I'm concerned about load balancing the HTTP traffic when both servers are alive, but also I have to keep the virtual IP alive if one server goes down; since I have two servers and same applications on both of them, I will care about redundancy also.
Hope this will clarify my query and my homeworks
Still any clue about the applications listed previously (LVS, Piranha, RH Cluster suite) will be appreciated.