# Integrating IP Mobility Management Protocols and MANET: A Survey
## 4 IP Mobility Management in MANET and Comparative Summary
### Proactive Gateway Discovery-Based Mobility Management Solutions
A mobile node is only entitled to register with one gateway to avoid duplicated binding to different foreign agents, which results in duplicated packets arriving to the foreign agents and thus to the mobile nodes. The proposed system enhances the DSR protocol to propagate mobile IP advertisements and registration messages. It attaches the signaling messages to DSR source routing information. It also extends the DSR to support external route discovery and external route maintenance functions. The external route discovery is used to distinguish between internal and external nodes. It also provides mobile nodes with information about all existing gateways in the network. This information is only used to identify whether the required address is local or external, however, and help the node to choose a gateway based on hop count metrics. More information related to QoS could be passed via the process of external route discovery, however, to improve mobile node selection of a gateway. Figure 8: An efficient integrated routing for interconnecting mobile MANET and the internet. _Global connectivity for mobile IPv6-based ad hoc networks_[42] proposed an IPv6-based MANET architecture that organizes MANET nodes into a tree structure in order to configure their IPv6 addresses. It uses Mobile IPv6 to support node mobility between different MANETs. The formed tree structure is rooted to an access router that acts as the internet gateway. The proposed system then uses a routing protocol based on the longest prefix matching. The proposed routing protocol does not require a path to be found to a destination prior to sending the traffic. Each mobile node instead maintains information about its parent and child nodes. The traffic is then forwarded following the longest prefix matching mechanism. The proposed system was applied to a small network size with low mobility to control the routing overhead. However, the proposed system relies on the root node of the tree structure, which is the gateway. If the gateway fails, the whole network will collapse. _Integration of mobile-IP and OLSR for a universal mobility_[43] proposed a hierarchical architecture (Figure 10) to connect MANET to the internet that handle mobile nodes mobility at different levels; macro mobility level (inter-domain) and micro mobility level (intra domain). The mobile IP protocol and the OLSR routing protocol were used to support large-scale mobility (macro-management) and local scale mobility (micro-management) respectively. The proposed system uses an OLSR gateway to interconnect each OLSR-IP subnet to the internet. An OLSR gateway is a router that plays the role of a foreign agent for visiting mobile nodes and the role of home agent for local network. It also uses an OLSR base station underneath the OLSR gateway in the hierarchical architecture, which is wired to the OLSR gateway and uses the OLSR routing protocol on the other interface to facilitate routing between the two networks. Each OLSR-IP network contains multiple OLSR base stations to offer load balancing for a local network. The proposed system also introduces another entity called OLSR-W, which is placed in the middle between the OLSR gateway and the OLSR base station, which acts as a traffic controller. A mobile node in the proposed structure is required to implement Mobile IP to be used for mobility management in case of mobile node movement to another OLSR-IP network. The system relies on the Mobile IP tunneling procedure to deliver traffic to a mobile node outside its home network, however the proposed system does not detail how the OLSR-W would contribute toward load balancing since all the routing follows the OLSR shortest path procedure. Figure 9: Integrating DSR-based mobile ad hoc networks with the internet [41]. Dynamic agent advertisement of mobile IP to provide connectivity between ad hoc networks and internet[44] proposed a dynamic advertisement scheme for MANET-internet integrated networks using Mobile IP and AODV with the goal of reducing routing overheads.