# Integrating IP Mobility Management Protocols and MANET: A Survey
## 2 IP Mobility Management Protocols
### Micro Mobility Management Solutions  
Mobile IP suffers excessive signaling overhead in its two variant versions when there is a frequent handoff within the wireless network. This is a result of the required control messages, whether between the mobile node and its HA, as in MIPv6, or between the mobile node and its HA and FA, as in MIPv4. This, however, leads to a need for mobility management protocols to handle mobility for scenarios where mobile nodes move and change their point of attachment frequently. The solution should provide a fast and seamless handover. In the following, we highlight some of the common mobility management protocols proposed for such micro mobility management. Figure 3: Route optimization in Mobile IPv6. Figure 2: Mobile IPv4. **HMIP** was introduced to enhance the performance of MIPv6 while minimizing the impact on it. HMIP aims to reduce signaling cost and binding updates resulting from frequent user mobility, and thus smooths and speeds up the handover process. It introduces a new functional node called the Mobility Anchor Point (MAP), which is located at a higher level of the hierarchical network structure. Figure 4 shows the HMIP hierarchical structure. The MAP is not required to be located at a top of each single subnet. It is intended to reduce the number of control messages that are usually sent outside the local domain. A MAP node is supposed to serve a domain consisting of multiple access routers. A mobile node is required to register with an access router to get an On-Link Care of Address (LCoA), and registers with a local MAP to get a Regional Care of Address (RCoA). The RCoA is the address used for communication with any CN node. If the mobile node moves into the coverage of a new access router within the local MAP, it registers with the new router, obtains a new LCoA, and notifies its MAP of the new LCoA. It will not inform the CN node of the new address since the RCoA is used for connection with the external node. When the MAP receives any traffic destined for the mobile node, it forwards the traffic to the appropriate access router according to its mapping knowledge. _Cellular IP_ was designed to handle mobility between subnets within the same domain. It can interwork with the IP mobility protocol to provide macro-mobility between different domains. The main components of cellular IP are the Base Station (BS), working as an access point, and the gateway router that is the boundary between a cellular IP network and the internet (see Figure 5). Gateways are used by the cellular IP to link subnets to the internet, and its IP address is used as the CoA for all mobile nodes within the cellular network. For location and routing purposes, cellular IP maintains two distributed caches by mobile nodes and cellular IP nodes. Packets sent by mobile nodes are used to update the cellular IP node cache. Mobile nodes maintain a map to the available cellular IP base stations. Mapping entries are updated through regular route-update messages. Cellular IP provides two approaches for handoff, hard handoff and semi-soft handoff, to allow mobility within a local domain. The first approach is fast and simple but comes with potential packet loss. In the semi-soft handoff, when a mobile node receives a signal from a new base station, it sends a semi-soft packet and returns to listen to the old base station. This will update the mapping cache. The final handoff takes place after a delay called a semi-soft delay. **HAWAII**: The Handoff-Aware Wireless Access Internet Infrastructure (HAWAII) is another micro-mobility protocol to manage mobility within a domain. HAWAII builds a home domain following a hierarchy approach as illustrated in Figure 6. Each home domain consists of the Domain Root Router (DRR), which acts as a gateway linking the local domain to the external network. The DRR covers several base stations and routers, which in turn serve mobile nodes.