With the recent growth in smartphone services, the "mobile" environment has become a key factor to consider in the design of the future Internet. In this paper, we propose Mobile-Oriented Future Internet (MOFI), which is a new architecture for the future Internet for mobile-oriented environments. The MOFI architecture is designed with three functional features: global identifier and local locator in the identifier-locator separation, query-first data delivery for route optimization, and distributed control of identifier-locator mapping. The proposed architecture and functional operations are implemented and tested using the Linux platform. From the experiment results, we see that the MOFI architecture performs better than the existing identifier-locator separation schemes, such as Proxy Mobile IP and Host Identity Protocol, in terms of data throughout, mapping control overhead, and handover delay. Keywords: Future Internet, architecture, local locator, query-first data delivery, distributed mapping control, implementation. Manuscript received Apr. 30, 2012; revised Jan. 15, 2013; accepted Jan. 26, 2013. This research was supported by the IT R&D support program of KCA (KCA-10913-05004), the ITRC support program of NIPA (NIPA-H0301-12-2004)  With the popularity of smartphones and the emergence of various wireless networks, the network environment has rapidly changed from fixed-based to mobile-based. Mobile technology is expected to become dominant and very common in the near future [1] . With this trend, the mobile environment is now a primary factor to be considered in the design of the future Internet. However, it should be noted that the Internet was originally designed for a fixed network environment rather than for a mobile network environment. This has resulted in various extensions being added to the Internet to satisfy mobility requirements, such as the Mobile IP (MIP) [2] and the Proxy MIP (PMIP) [3] . However, this patch-on approach is just a temporal heuristic rather than a permanent optimal solution. Some efforts have been made to support Internet mobility in the transport layer, as shown with the Multipath Transmission Control Protocol (Multipath TCP) [4] and the Stream Control Transmission Protocol (SCTP) [5] . These transport-layer mobility schemes can be used to support the seamless handover for a multihoming host in mobile networks. However, such schemes do not consider the important mobility issues on identifier-locator (ID-LOC) mapping control and location tracking for mobile hosts (MHs). Recently, the Host Identity Protocol (HIP) [6] and Locator/Identifier Separation Protocol (LISP) [7] were discussed for ID-LOC separation in the network layer. However, HIP and LISP depend on a centralized ID-LOC mapping system, such as Rendezvous Server (RVS) in HIP or Map Server in LISP. Regarding scalability, this centralized approach still has the drawback of traffic concentration at a central server [8] . Based on these observations, a variety of research projects emerged to design the future Internet, which included the development of eMobility [9], 4WARD [10], FIND [11] , and MobilityFirst [12] . Each work was developed with its own distinctive features and design goals. In this paper, we propose Mobile-Oriented Future Internet (MOFI), which is a new architecture for the future Internet that is a part of a project sponsored by the Korean government [13] . The MOFI architecture is designed with three functional features: Global ID and Local LOC (GILL), Query-First Data Delivery (QFDD), and Distributed ID-LOC Mapping System (DMS). In GILL, each host has a globally unique Host ID (HID), whereas a local or private IP address can be used as a LOC for packet routing within a network. In QFDD, the signaling operation for the LOC query is performed so as to obtain an optimal path before data transmission. In DMS, the ID-LOC mappings for hosts are managed by each access router (AR) in a distributed way. With this MOFI architecture, in this paper, we describe the relevant data delivery and ID-LOC mapping control operations, which are implemented and tested using the Linux platform. This paper is organized as follows. In section II, we compare the main design features of the proposed MOFI and the existing ID-LOC separation schemes. Sections III and IV describe the architectural design of MOFI and the relevant control operations, respectively. In section V, we discuss a Linux-based implementation of MOFI. The performance analysis is given by experimentation in section VI. Finally, section VII concludes this paper. We first discuss the design features of MOFI respective to architecture. Table 1 compares the main features of MOFI with those of the existing PMIP and HIP schemes. We note that MIP is identical to PMIP, and LISP is similar to HIP regarding the ID-LOC separation principle. For mobility support in the network layer, the ID and LOC need to be separated, since an MH may change its LOC by movement, but its ID will not be changed. The ID-LOC separation approach is also taken in PMIP and HIP. In PMIP, the home address is used as the ID, and the care-of-address is used as LOC. In HIP, the Host Identity Tag (HIT) is used as the ID, and the IP address of a host is employed as the LOC. In PMIP and HIP, a globally unique IP address is used as the LOC. However, this global uniqueness of the IP address may incur the well-known routing scalability problem in the BGP In MOFI, an HID is used as the ID, which is similar to the HIT of HIP. The distinctive feature of MOFI is to use a local LOC, rather than a global LOC. That is, the end-to-end communication between two hosts is performed with their global IDs, whereas the data packets are delivered possibly via one or more networks by using local LOCs. Such LOCs may be local or private IP addresses, which are specific to the associated transit networks. With this local LOC feature, the routing scalability problem can be alleviated. In MIP or PMIP, all data packets destined to an MH are first delivered to the Home Agent or Local Mobility Anchor (LMA). This data-first feature induces a non-optimal path for data delivery between the two communicating hosts in the network. In a mobile environment, a host frequently moves around in the networks. To use an optimal data path from the initial data transmission, we need to consider the query-first approach in the data delivery model. In this approach, the LOC query operation to find the location of an MH is performed before data transmission. This query-first approach is taken in MOFI as well as in HIP. Under the ID-LOC separation, one of the challenging issues is how to control the ID-LOC mapping information. PMIP and HIP use a centralized agent for ID-LOC mapping control, such as LMA of PMIP and RVS of HIP. In the centralized scheme, all of the ID-LOC mapping control messages are delivered to a centralized agent. Such centralized control schemes, however, tend to inject unnecessary traffic to the core network and may incur a traffic explosion problem. Moreover, the centralized approach is vulnerable to the failure of a central anchor [8] . To alleviate the problems of the centralized mapping system, we choose the distributed mapping control approach in MOFI. In the distributed mapping control, the mapping control traffic 2. Protocol Stack for Data Delivery will be distributed onto each AR in the network. Additionally, security in the MOFI architecture may be another important issue, which was discussed in previous work [15] . Regarding protocol stack, MOFI takes a layered model similar to the TCP/IP architecture. Figure 2 shows the protocol stack considered in MOFI. The current application layer, transport layer, and MAC/PHY protocols are reused in MOFI. As for the network layer, the current IP protocol performs end-to-end communication (by using a socket interface with the upper layer application) and data delivery (or routing). In MOFI, the network layer is divided into the following two sublayers: communication and delivery. As HIP uses an HIT, MOFI uses an HID to identify a host in the network, which is globally unique on the Internet. We consider the 128-bit HID format for compatibility with IPv6 application. The LOC is used for delivery of data packets. In MOFI, the LOC is defined as a locally routable IP address that must only be locally unique in the concerned network. The communication sublayer is responsible for end-to-end communication between the two end hosts, which may be implemented as a shim layer protocol between transport and network layers. The delivery sublayer is responsible for packet routing in the access and backbone networks. The current IP routing schemes can be used for data packet routing.
The binding between the HIDs and LOCs was achieved by access router which has a hash table, an HID-LOC register, and local mapping controller REF .
Mobile Oriented Future Internet (MOFI): Architectural Design and Implementations
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