Systems and methods for forming an incident area network

A first and second subsystem comprise a respective domain name server (DNS) 116, 136, global application instance 118, 138, localised application instance 120, 140, and network address translator (NAT) 122, 142. An incident area network is formed when a network connection 402 between the sub-systems is detected, initiating a synchronisation process. The first DNS transmits a first global address 128 for the first global application and a corresponding first name 126 to the second DNS; the first NAT transmits the first global address to the second NAT; and the first localised application instance synchronises with the second localised application instance. After the synchronisation is complete, a mobile device 124 on the first sub-system may be relocated in a handover procedure to the second sub-system. A virtual network address may mapped to both first and second localised application instances, with each respective NAT readdressing the packet accordingly. Packets addressed to a global application may be forwarded to the relevant global application instance. The second DNS and NAT may transmit data to update the first DNS and NAT with the second global address and name. The first and second application instances may perform database synchronisation.