snmp on rhel cluster : from virtual address to a node

I am currently trying to set a server/client configuration, and i'm struggling a little with snmp behaviour. Just to precise, i'm not really into linux administration, nor network administration, so don't be surprised if my questions are sometimes newbie ones.

My architecture is the following :

• 2 servers on rhel6, with ip xxx.xxx.xxx.1 and xxx.xxx.xxx.2
• The 2 servers are configured with cluster suite (failover), so i have a Virtual address: VIP is xxx.xxx.xxx.3 (let's say the master is xxx.xxx.xxx.1 for the discussion)
• N nodes on centos6 (xxx.xxx.xxx.10, xxx.xxx.xxx.11, ...)
• All machines (nodes and servers) are on a unique LAN (no routers, no firewall, no routes, ...)
• No DNS, everything on static on hosts files

I wanted the master server (the one who's the master in cluster) to monitor the nodes with SNMP. So I configured the snmpd file on the nodes, specifying the host with the VIP xxx.xxx.xxx.3. I did the same configuration on the servers, in order to enable the master to monitor the slave server too.

What is happening is the following :

1. When I execute a snmpwalk from the master to a node, i reach a
   timeout. Using tcpdump, I can see the request is well sent by the
   master, and the node receive it. It seeems the node doesn't answer
   corrtectly
2. When I execute a snmpwalk from the master to the slave, everything is ok. If I change the SNMP configuration on node, specifying the host with the master address (xxx.xxx.xxx.1 for instance) it's OK.

So what I think :

• I have read that SNMP is not cluster aware; I feel i am right into the problem but I don't manage to get what's happening. From what i've seen in 1) and 2), I would say the node doesn't answer to the VIP, but the real address of the master (didn't have the time to check with tcmpdump)
• But if it's true, why the snmpwalk on the slave is working ? I would have expected the same behaviour

Should I specify on the nodes both address of servers instead of the VIP, Is it a clean solution (still have to check if it's working) ?

Or do I need to specifically configure the snmp client on the node (snmp.conf) ? I didn't modify this one at all.

Thanx for your help, I'm a little lost in there.