Integration of IP Mobility in OPNET: Modeling and simulation

Using the base MIP protocol, two routing inefficiencies can be observed. The first is what’s called triangular routing: all traffic for the mobile node has to go through the home agent, increasing the routing path from the corresponding node to the mobile node. A possible solution is to let the correspondent nodes tunnel traffic directly to the care-of address: when the home agent first intercepts traffic destined for a registered node, it sends a socalled binding update to the correspondent node, providing it with the tunnel endpoint. A second issue is when a mobile node changes networks: traffic in flight to the previous foreign agent care-of address is lost after the mobile node has left that network. By notifying the previous foreign agent of its new location, packets in flight can be re-tunneled to the new care-of address and possibly update a correspondent node of the new address. These improvements are bundled in an extension to Mobile IP called Route Optimization [2]. Abstract This paper presents the design, the implementation and the enhancements required to provide IP mobility in OPNET Modeler. The following mobility protocols are integrated into the standard OPNET models: Mobile IPv4, Route Optimization and Regional Tunnel Management (Hierarchical Mobile IP). Two types of activities can be distinguished. Firstly, the standard OPNET IP stack was modified with new features (e.g. proxy ARP, routing enhancements, etc.). Secondly, new process models were developed, such as tunneling, mobility registration, etc... The resulting models are then applied to a number of case studies where performance measures (delay, packet loss) are determined for various WLAN mobility scenarios which illustrate the effect of Mobile IP on transport-level protocols.