about IPsec
 

Is the IPsec will support the NATing concept.some body saying it will support and somebody not.please can you help me.....

as their own technologies, they don't have anything to do with one another. can you give a context to actually understand the probelsm you're having?

Let me explain a context where i faced this problem.

Some body in a private network( a branch office ) with private ip address is going to communicate with the peer system which is located in another private network ( a head office) with its private ip address itself. In this scenario, i need to offer security for the packets through ipsec.

So, In this context, whether my packets in one branch is natted by the NAT router or not. Because, i heard that IPsec doesn't support NATing concept. Then how does my packet with IPsec security goes to that peer system.

ok, well ipsec as a protocol doesn't use port numbers, unlike tcp or udp as such it is not possible to easily nat an ipsec packet as it traverses a device like an adsl firewall, which naturally nats traffic from an internal subnet to the single public ip. to get around this, many ipsec implementations will allow the option of adding a dummy tcp or udp header, allowing for an arbitrary port number to be added. this then can be used within a nat table to manage the connections.

in your scenario though, you have an ipsec tunnel between two edge devices at the sites? from there, there's not going to actually be any natting taking place, as the peers themselves will be the public addresses. if there's a single vpn termination point behind the edge device, then you would conventionally just forward all ipsec traffic to that internal device.

Thanks for helping me to uderstand ipsec concept