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Managing Mobility with SDN: A Practical Walkthrough
Published in Hrishikesh Venkatarman, Ramona Trestian, 5G Radio Access Networks: Centralized RAN, Cloud-RAN, and Virtualization of Small Cells, 2017
Xuan Thuy Dang, Manzoor Ahmed Khan
Mobility management guarantees continuous sessions and uninterrupted data access for mobile devices. IP protocol has been the main protocol for the global Internet. However, it was not designed for mobile computing systems. The evolution toward mobile Internet has created architecture and protocols to connect mobile systems with the Internet. Currently, there are two main forms of mobile architecture in the mobile domain. One form of architecture is driven by the 3rd generation partnership project (3GPP), which sets standards for 2G, 3G, and the current 4G’s LTE system. The other form of architecture is designed for device mobility in IP-based networks with IEEE’s mobile IP protocols: mobile IP (MIP), MIPv6, proxy mobile IPv6 (PMIPv6), and their derivatives. Although mobile connectivity is supported, both systems feature a centralized architecture with a central mobility anchor and dedicated mobility management entity for each mobile domain. In LTE systems the local mobility anchor is P-GW and device mobility is handled by a mobility management entity (MME). The respective elements in PMIP systems are a local mobility anchor (LMA) and mobile access gateway (MAG). These centralized, specialized designs have some scalability and flexibility problems that result in some cost and performance issues in order to meet future demands. For example, given the huge and unpredictable use of mobile data, overprovisioning becomes a costly and less timely expansion approach. The complexity of those systems also infers high operation costs and additional end-to-end delays. Current mobile systems have operational and performance limits while mobile data demand keeps growing in terms of bandwidth, latency, and service availability.
Software-Defined Networking Techniques to Improve Mobile Network Connectivity: Technical Review
Published in IETE Technical Review, 2018
From the earlier works, it can be observed that the proposed works rely heavily on the controller as it holds important information of a network such as MN's HoA and CoA and to which OFS a MN is attached, in order to calculate the path to reach MN and push a new rule to OFS. Different approaches can be seen from here as Pupatwibul et al. [9] maintained the concept of MIP, at the same time eliminating triangle routing issue by using the same IP even if MN changes location. Not only the optimal path between CN and MN will be found with OpenFlow controller, CN can always use the same destination address to send packet with the help of HA which will rewrite the destination address to the latest address of MN. This approach is different from Wang and Bi's [10] that used controller to cache the latest address of MN and construct flow entry to reach MN. Although Wang and Bi [10] and Pupatwibul et al. [9] both use rewrite address action in order to hide the change of IP address from CN, Wang and Bi [10] choose to rewrite the destination address to the last one-hop switch to MN instead of the latest address of MN. This result in one extra rewrite address action needed on the packet before reaching the destination. Moreover, Wang and Bi [10] did not address whether General Packet Radio Service (GPRS) Tunneling Protocol (GTP) is being supported or handled in the OpenFlow protocol design they have used. This is because OpenFlow 1.3 [32] has started supporting matches of metadata tunnel ID which can be used to match GTP tunnel's tunnel endpoint identifier. Kim et al.'s [11] approach on using OpenFlow-based Proxy Mobile IPv6 (OPMIPv6) has succeeded in reducing the use of IP-in-IP tunneling which indirectly caused triangle routing issue. With the use of SDN, mobility function of Proxy Mobile IPv6 (PMIPv6) is delegated to OpenFlow controller where management is improved due to the ease of controller replication; meanwhile, workload can be optionally divided with the cluster ability of SDN controller. In conclusion, the works above have succeeded in reducing or eliminating triangle routing issue; however, the works did not evaluate how the mobility of MN affects the performance of application such as connection-oriented data session. Besides, the above works clearly show that the controller serves as point of convergence as its intelligence is required mainly for constructing new flow, caching important info of MN, therefore, making it the sole point of security issue related to compromise the mobile network.