Contents I. Introduction
Maintaining the IP address is one of the characteristic of mobility management to provide session reservation and ensure continuous service, even if the mobile node changes location. In the current research of mobility management, there are two methods for mobility management. One is the centralized mobility management method. The other is the distributed mobility method. In the centralized mobility management method, every packet has to go through the mobility anchor that manages mobile nodes. It is an efficient way to manage a node, since it has a single management entity. However, if the controller fails, it will cause damage to the entire network [1]. To solve current problems, such as single point of failure (SPOF), in the IETF WG, distributed mobility management is proposed. At first, a fully distributed method uses a distributed method for both the control plane and the data plane. Therefore, it does not require another entity. It uses messages to gather information about nodes between mobility anchors [2]. However, this scheme causes message overhead since all mobility anchors have to get node information using messages. Moreover, this scheme may not support route optimization when a mobile node moves to another anchor, because the previous router has to work as an anchor router for supporting previous service. In a partially distributed method, the control plane and data plane are decoupled. It uses a centralized method for the control plane and a distributed method for the data plane [3]. In a partially distributed method, there is one entity that stores the BCEs allocated for the mobile nodes in the mobility anchor. It is more efficient because it uses a centralized database for gathering node information; however, this method also has some problems, such as tunneling and non-optimal routing. On the other hand, one of the new network paradigms is the software defined network, which decouples the control plane and the data plane [4]. It is similar to a distributed mobility management scheme. Moreover, SDN can support various APIs running on controllers; it should be helpful to define a new entity for mobility management. Therefore, in this paper, we applied the SDN concept to DMM architecture, defined procedures of mobility support and analyzed signaling costs using numerical analysis. The remainder of this paper is organized as follows: section 2 presents related work, section 3 presents our proposed scheme, section 4 presents cost modeling and section 5 presents numerical result and analysis. In the last section, we conclude the paper and make recommendations for future work.
