# Integrating IP Mobility Management Protocols and MANET: A Survey
## 4 IP Mobility Management in MANET and Comparative Summary
### Hybrid Gateway Discovery-Based Mobility Management Solutions  
The hybrid gateway discovery approach combines the proactive and the reactive approaches to create a balance between gateway advertisement overhead and the delay of discovering gateways. In such an approach, the nearby mobile nodes are provided with gateway advertisement, however distant nodes must use solicitation messages to discover gateways. This section has introduced six proposals that use Mobile IP and follow the hybrid gateway discovery approach and they are summarized in Table 3.  
_Mobile IP support in ad hoc networks with wireless backbone_[54] proposed agent discovery and route discovery schemes to enable Mobile IPv4 in on demand ad hoc networks. It uses stationary internet gateways and wireless routers to support mobility management. In order to reduce broadcasting overhead in the network, the proposed solution limits agent advertisement broadcasting and utilizes proxy agent advertisement instead. It employs destination address cashing in internet gateways and  
\begin{table}
\begin{tabular}{p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt}} \hline \hline
**Scheme** & **Features** & **Mobility Scheme** & **MANET Routing** & **Handoff Metrics** & **Gateways** & **Evaluation(Simulation)** \\ \hline \multirow{5}{*}{[PERSON] et al. [49]} & Use simple additive weighting technique to calculate QoS. & \multirow{5}{*}{MIPv4} & \multirow{5}{*}{AODV} & Traffic load, path quality and hop count. & & Simulated in NS2, 50 nodes, 15 are traffic sources, compared to variants of the system: minimal hops selection based, traffic selection based and path quality based. \\  & Use simple additive weighting technique to calculate QoS. & & & & & \\  & Solicitation message is broadcast by nodes to discover gateways. & & & & & \\  & Eliminates gateway & & & & & \\  & Eliminates gateway advertisement from Mobile IP. & & & & & \\  & Solicitation message is broadcast by nodes to discover & & & & & \\  & Solicitation message is broadcast by nodes to discover & & & & & \\  & Solicitation message is broadcast by nodes to discover & & & & & \\  & Solicitation message is broadcast by request message to discover gateway. & & & & & \\  & Solicitation message is broadcast by request message to discover gateway. proxy route reply to reduce delay while discovering external destination. The proposed system applies a priority-based route request rebroadcasting scheme during the route discovery procedure to allow a mobile node to select more stable routes. Since the proposed system limits the rebroadcasting of agent advertisement, a mobile node that is multi-hops away should broadcast an agent solicitation message to discover the internet gateway. A wireless router can reply to the agent solicitation on behalf of the internet gateway. A roaming mobile node is required to identify a foreign agent and registers with its home agent using the foreign agent. Any traffic destined to the mobile nodes will be tunneled to the new foreign agent. The proposed system introduces a wireless router entity in addition to the internet gateway to the structure of the integration, which comes with expenses. There is also no explanation of the interoperability between a MANET protocol and Mobile IP, and the system was not evaluated. _Integrating mobile IP with ad hoc networks_[55] proposed an architecture (Figure 12) that connects MANET to the internet using Mobile IP and DSDV. The architecture is divided into multiple MANETs, each connected to the internet using a fixed gateway node. The border of each individual MANET is defined by its gateway. Gateways use Mobile IP to operate as foreign agents for local MANET nodes. They advertise their presence via the periodic broadcasting of an agent advertisement message. Mobile nodes use the agent solicitation message scheme as well in case they do not receive the periodic advertisements. In order to define the service scope for each gateway, the proposed system associates a parameter N with each gateway.