Results: Fault Tolerance

Figure: The robustness of IP, MIP (tri/bi), and ROAM.

In addition to stretch, we also simulate node failures. We vary the failure probability of the clients and servers from 0% to 50% and perform 10,000 runs. In this simulation, we assume that both the MH and CH are mobile and have a HA. We assume that IP routing succeeds when both the MH and CH are operational. We assume that MIP is functional when the MH, CH, MH's HA, and CH's HA are operational. We assume that ROAM is functional when the MH and CH are operational, and the MH and CH can both find an operational trigger server in their caches (of size 10).

Figure 13 shows the results of failing nodes on the likelihood of connectivity between the MH and CH. When nodes have a 5% chance of failing, MIP has a 85% likelihood of successful connectivity. When nodes have a 15% chance of failing, MIP likelihood of successful connectivity drops to only 50%. MIP is vulnerable to the failure of the HA's network connectivity. In most cases, a host has only one HA in its HN. As a result, if the HA's network connectivity fails, the MH is unreachable. In contrast, a ROAM host can use any $i3$server in the Internet. As long as one $i3$server is operational and the ROAM host has IP connectivity, the host is reachable.