# Tunnel-Free Distributed Mobility Management (DMM) Support Protocol for Future Mobile Networks
## 1 Introduction
Connections can be established to the two BMAs simultaneously, and in this manner, the MN can communicate with two BMAs. With the availability of more than one active connection through the handover process, this leads to a more seamless and reliable handover performance. Once the handover with the MBB is complete, the connection to the previous BMA is dropped, and the MN continues to communicate with the new BMA. Since the establishment of the DMM working group in 2012, research is in progress that focuses on providing mobility management in a distributed manner. As DMM is yet to be standardized, substantial research [5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22] has been done in this area. DMM has been introduced as an architectural model to facilitate the surfacing mobile IP networks [5]. There is the need for a change to move toward more flat architectures from the current hierarchical trends. The standard-making bodies like IETF and 3 GPP (3 rd Generation Partnership Project) are developing designs to facilitate DMM needs and requirements. DMM approaches have been classified into client-based, network-based, and routing-based approaches. In the client-based approach, the existing suggestions plan on distributing the anchoring by installing more than one HA at the edge of an access network. If the MN is on the move, the previous session is maintained by tunneling and is forwarded to the care of address (CoA). Bi-directional tunnels are used to ensure session continuity between the MN and each HA. Tunneling and address management is one of the challenges of DMM, and there is a need for a more efficient tunneling mechanism, as well as the management of multiple IPs assigned to MN along the way. [PERSON], [PERSON] et. al. [6] have discussed DMM from the perspective of IETF. They have discussed how the IETF DMM workgroup plans to distribute mobile internet traffic in an ideal way while deploying the mobility anchors in a distributed manner. They have discussed in detail the two possible DMMapproaches, i.e., a host-based DMM approach and a network-based DMM approach, along with their comprehensive comparison. They have pointed out the four main challenges faced by DMM: address and tunneling management, registration delay and signaling overhead, network configuration and resource management, and security considerations. [PERSON], [PERSON] et al. [PERSON] et al. (2018) have proposed a DMM protocol for host-based IPv6 mobile networks. They have introduced an access mobility anchor at an access network level. Mobility signaling is handled by the MN itself. The MN is attended by its nearest mobility anchor. They have compared their design to MIPv6 in terms of throughput and handover delay. On the other hand, they have kept their analysis limited to only one mode of MIPv6, i.e., bi-directional tunneling, and they have not considered a MIPv6 route optimization mode. [PERSON], [PERSON] et al. (2018) have discussed DMM architecture and deployment scenarios. Two types of deployment scenarios were given: network function virtualization and selected internet IP traffic offload/local IP access scenario in 3 GPP. The first type suggests the separation of data and control planes. Mobility management is provided in two ways: mobility management functions with separate control and data planes under one controller, or with separate control and data planes with separate control in core and access networks. [PERSON] et al. [PERSON] et al. (2018) have proposed a DMM design that offers global and local mobility support in a distributed fashion called distributed dynamic MIPv6. They have performed an analysis considering the mobility costs. Global mobility is ensured by keeping a record of the most recent session entry even after it is terminated. [PERSON], [PERSON] et al. [PERSON] et al. (2018) have explored distributed and dynamic mobility management in the context of mobile internet. They have discussed the issues, challenges, and existing DMM approaches.