IPMN Architecture
	At the mobile node, when the link layer detects signal fading and initiates L2 handoff (event 1), it signals the subscribing application. When the event is received at the application layer, a Transientware module (handler 1) is activated immediately; this module simply makes a simple system call which lets TCP advertise a zero window to the correspondent node. This would normally cause the correspondent node to stop transmission. When the mobile node gets a new IP from the future network (event 2), it activates (handler 2) which transmits the future IP to the correspondent node at TCP level through a system call. The new IP is sent in a special TCP segment with ‘option=SWITCH_IP’. At the correspondent node, When TCP recognizes this option (event 4) it activates (handler 4) which then triggers a switch_ip() system call to replace the ‘destination IP’ field in the TCP/IP stack with the newly received IP number. Meanwhile, at the mobile node (handler 2) also makes a similar system call which changes the ‘source IP’ filed in its own TCP/IP stack. When the previous ‘SWITCH_IP’ segment is ACKed at the mobile node (event 3), the mobile node advertises a non-zero window to the correspondent node which enables it to resume transmission.