# Anchor-Based Method for Inter-Domain Mobility Management in Software-Defined Networking
## 1 Introduction  
Today's Internet is predominantly driven by wireless technology and its extensions. When coupled with the Internet, wireless technology provides access to a myriad of services available at all times, even while on the move [1]. However, this extensive use poses a problem when considering the design of the Internet. The architecture of the Internet is primarily based on logical connections between a clearly identified source, which includes its IP address and other parameters, and one or more identified recipients. Hence, when even one of these parameters is modified during movement, the connection is reset, potentially causing intolerable delays for certain real-time service applications. Ensuring service continuity during the movement of a mobile node is a genuine challenge as some applications and services are less tolerant of disconnection delays. Hence, the problemaddressed in our study can be stated as follows: Given a multi-domain network, and a mobile node in the network, how can we find a path to reduce data transfer delay when the mobile node moves between two different domains. The challenge of managing mobility in multi-domain networks, especially in ensuring uninterrupted IP traffic flow, has been a persistent challenge that has been tackled through different methods throughout the years. These solutions, such as Mobile IP, Proxy Mobile IP, and Distributed Mobility Management, have unique benefits and drawbacks. Lately, software-defined networking (SDN) has become a promising solution for managing networks effectively. In fact, SDN is a network architecture that aims to be dynamic, manageable, economical, and flexible in order to be appropriate for the high-bandwidth, dynamic applications of today [2]. Its fundamental idea of dividing the control plane from the data plane has made a revolution in networks possible in a number of ways [3; 4; 5]. SDN controllers make up the control plane, whereas switches, or forwarding elements, make up the data plane. A number of benefits are provided by SDN, including bespoke application-driven network management, flexible programmable control, and dynamic routing [6; 7]. By integrating SDN with mobility management, an improvement of route selection is achieved when a mobile node (MN) moves within an SDN domain [8]. In the context of SDN, a domain typically consists of network devices (e.g., switches, routers) managed by a single SDN controller [9]. Moreover, a domain refers to a logically or physically bounded part of a network that operates under a specific administrative control. The role of SDN in a multi-domain architecture is crucial, as it enables centralized control over heterogeneous networks while ensuring interoperability between different domains. This capability is particularly relevant in scenarios involving mobility management, where seamless communication across domains is essential for reducing latency and ensuring service continuity. To address this issue, we propose a routing method based on SDN and the mobility anchor principle for inter-domain mobility management. The domain used as an anchor is a domain responsible for retrieving data from a mobile node on the move and creating a tunnel between it and its correspondent in order to facilitate communication and reduce the data transfer delay. To sum up, our main contributions are threefold:  
1. We model the problem of inter-domain mobility management in SDN-based architectures as a problem of selecting an efficient route belonging to a set of routes. The chosen route reduces a metric that incorporates bandwidth availability, the number of hops between the mobile node and the anchor domain, and the number of hops (i.e., domains) between the anchor domain and data destination node or the corresponding node. 2. We propose an algorithm to select an anchor domain that is closest to the data destination node. This strategic placement contributes to reducing the overall data transfer delay. 3. We develop an algorithm specifically designed for route selection within the SDN framework.