# 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
Thereafter, MANET nodes can register with the home agent through recently discovered foreign agents. This version of MEWLANA optimizes the DSDV routing table information where MIP floods the advertisement message only if the routing table has a new entry for a node that just joined the network. However, firing mobility traffic in addition to DSDV traffic is seen as a drawback of the proposed system, and instead the DSDV traffic should be used to deliver mobility traffic. The other version of MEWLANA is _MEWLANA-RD_, which is based on a proposed root driven routing algorithm TBBR. MANET nodes and the foreign agent are organized as a tree structure with the foreign agent as the root of the tree. Beaconing from the foreign agent is used to form the tree structure and each mobile node has a depth level number, which is the hop count of the arriving beacon. A mobile node can only process a beacon with a hop count less than its depth level number. After construction of the tree structure, each mobile node registers with the foreign agent by sending a multi-level registration request to its parent in the tree structure. Mobile IP is used to route traffic to its destination. If two mobile nodes are in the same MANET domain but in different tree structure, the traffic destined between them needs to go through home agents and then foreign agents. The system is claimed to suit a large MANET with low internal traffic, however, the use of a root node at the top of the structure would make the gateway susceptible to congestion and therefore a single point of failure. **MIPMANET** was proposed by [47]. MIPMANET provides mobility management services for MANET networks connected to the internet. It incorporates traditional Mobile IP with an AODV routing protocol. Mobile IP foreign agents are used as access points for MANET nodes. MIPMANET uses the Mobile IP agent advertisement scheme to announce access point presence. Each foreign agent is required to broadcast an agent advertisement in every five second period, compared to one second in the traditional Mobile IP. Mobile nodes that wants internet access are required to register with one of the foreign agents based on the distance metric. For routing purposes, MIPMANET uses the default route concept in AODV routing tables, where a mobile node sets its foreign agent as its default route entry. However, the default route is only used after a node broadcasts an AODV route discovery message and finds no route to the desired destination. The OADV route discovery message is also used in the proposed system to find a route to the foreign agent. Roaming between different foreign agents is supported in MIPMANET using the hop counts criteria. A mobile node can register with a new foreign agent if it is two hops closer to the new foreign agent than the current foreign agent. The proposed system can experience long delays before a node can connect to other entities on the internet, however. This is due to the delay in discovering the gateway, when a node must search the whole network and if no route is found, the default route will be used. The delay can also be seen as a result of the high frequency of firing the gateway advertisement. Table 1 shows a summary of the proactive gateway discovery-based mobility solutions.