Special Edition Using TCP/IP, Second Edition

Mobile IPv6

One of the biggest disadvantages in implementing mobile IP has been its undue overhead because of the fact that datagrams need to travel in a triangular circuitous path during the exchange of datagrams between the mobile device and the destination computer. This problem, called the triangular forwarding problem, worsens when the destination computer is located on the foreign network. In this case, the datagrams sent by the destination computer must travel all the way back to the home agent and must be transmitted back to the foreign network. This means that the datagram must cross the foreign network boundaries two times, giving the anomaly its name, the Two-crossing problem. Figure 25.5 shows you how the Two-crossing problem ...