[j-nsp] Ipsec tunnel between Cisco and juniper srx

[Roman]

Hi, 

i want to do this

My_Cisco(Public_IP) -- Internet -- router(NAT_ISP) -- My_Juniper_srx_(private_ip)
                    |                                                                                        |
                    |-------------(Ipsec_Tunnel)_or_(gre_over_ipsec)-------------------------| 

What is the best way to do this?