I am using RHEL 5.3 with cluster suite.
I need to configure a two node cluster which belongs to the same VLAN.
Each node has two NICs and each NIC has two IP addresses, so in total I have 4 IP addresses.
Is there any way (a normal or a forced way, like changing the cluster.conf) to have this cluster working with one VIP service?
Because when I use Conga, I can only configure one IP on each node.
Eventually, the network will look like:

---------------------------
| Switch |
---------------------------
| | | |
|eth0 |eth1 |eth0 |eth1
| | | |
-------- ------------
| Node A | | Node B |
-------- ------------

IP_eth0_A = 10.10.10.2
IP_eth1_A = 10.10.10.4
IP_eth0_B = 10.10.10.3
IP_eth1_B = 10.10.10.5
VIP=10.10.10.6

Note 1: I cannot have a virtual server for our system, this is mandatory

I know it is a very weird configuration, but that's the way it is

First, if you are not aware, having multiple interfaces with IPs on the same subnet can present its own set of problems if not properly implemented (port flapping, mac flapping, arp-flux, ...). With a little work this can be mitigated if it must be done. The ARP Flux Problem


That said, let me make sure I understand... when you say cannot have a virtual server in this context, are you meaning that the system can not be virtualized (VMware guest, KVM or xen domU, ..., ...)?

I'm not certain what steps you are taking to configure VIPs for use with clustered service(s), but you should be able to within Conga's luci management interface. It should be a resource for whatever service you are intending to provide. If the vIP itself is the service then you'll want to make a custom initscript for it that honors at least start, stop, status with expected exit codes for the cluster to monitor if you want to be able to failover the vIP(s). Although, without more context and what service you want to bring under Conga's control for HA, I'm just making some big assumptions.