NAT Traversal (NAT-T) technology can detect whether both IPSec peers support NAT-T. NAT Traversal (NAT-T) technology can also detect NAT devices between IPSec Peers. ISAKMP Main Mode messages one and two are used to detect whether both IPSec peers support NAT-T. If both IPSec peers support NAT-T, NAT Devices are detected in ISAKMP Main Mode messages three and four.f