Communication system, a base station and a communication method for femtocell

Femtocell base station obtains the IP address of the CS relay apparatus from the first management apparatus, based on the IP address of the acquired CS relay device, connected to the CS relay device, CS relay device establishing a first IPsec Tunnel between. Furthermore, a femtocell base station an IP address of the PS relay device via a first IPsec Tunnel obtained from the second management apparatus, based on the IP address of the acquired PS relay device, for PS connected to the relay device, establishing a second IPsec Tunnel between the PS relay device.