Yunchul Choi

A flow entry management scheme for reducing controller overhead

In this paper, we advocate addressing the communication overhead problem between OpenFlow controllers and OpenFlow switches due to table-miss in a flow table. It may cause the communication overhead between controllers and switches because a switch has to send packet-in message to a controller for processing table-missed flows. We propose a simple flow entry management scheme for reducing the controller overhead by increasing the flow entry matching ratio. By using an LRU caching algorithm, a switch can keep the flow entries in a flow table as many as possible, and then the flow entry matching ratio can be increased.

Verification for NFV-enabled network services

Network Functions Virtualization (NFV) offers a new way to design, deploy and manage network services. NFV relocates network functions from dedicated hardware appliances to generic servers, so they can run in software. Also, it is designed to consolidate and deliver the network components needed to support a virtualized infrastructure including virtual servers and storage, as well as networks. However, incomplete or inconsistent configuration of virtualized network functions (VNF) and forwarding graph (FG, aka service chain) could cause breakdown of the supporting infrastructure. Moreover, automation of NFV process with integration of Software-Defined Networking (SDN) technologies may lead the network services to be more error-prone. Recognizing these problems, we need to identify key properties to be checked. In this article, we present a framework of verification for NFV-enabled network services. Its goal is to provide a formal method for the network services that can be used to build and verify NFV components. Overall, this method makes it safer and more reliable for network operators to compose their network services in NFV environment, so that they can be assured that the properties are correctly enforced.

Evaluations of a multiple flow tables construction scheme for service function chaining

In this paper, we present evaluation results of Service Function Chaining implementation scheme using multiple flow tables of OpenFlow. With a single flow table in the implementation, the number of flow entries in the flow table significantly increases as the number of service chains increases. This results in looking up larger flow table and higher processing time in processing packets. We have addressed this problem in the previous work with the modified flow table construction scheme that exploits multiple flow tables. The proposed scheme classifies the incoming packets with VLAN tagging and switches can look up only the corresponding flow table to process the packets. By evaluating the proposed scheme, we identify its performance enhancement in terms of the number of flow entries and flow entry lookups.

A multiple flow tables construction scheme for service function chaining in NFV

In this paper, we address the inefficient implementation of Service Function Chaining, which comes from the use of a single flow table. It is because the number of flow entries in the flow table significantly increases according to the increment of the number of service chains. So the switch should look up larger flow table to process packets, and this also makes harder to update the path of the service chains. In order to solve this problem, we propose the modified flow table construction scheme for implementing the Service Function Chaining with multiple flow tables. In our scheme, the flow entries are inserted to the corresponding flow table classified as the input ports of the switch, then they can be easily categorized and managed through the multiple flow tables. By doing this, the switch can look up only the corresponding flow table to process the packets or to update the path of the service chains. As a result, we reduce the inefficiency of the flow table construction for implementing the Service Function Chaining in the NFV.

Flow table management scheme applying an LRU caching algorithm

In this paper, we address the communication overhead problem between OpenFlow controllers and switches due to table-miss in a flow table. For dealing with table-miss, the switch informs the controller by sending a packet-in message to make the controller perform further actions. However, this packet-in procedure to deal with table-miss may cause a controller overhead when one controller has to process many events. For reducing the controller overhead, we propose a modified flow table management scheme with applying an LRU caching algorithm. By keeping the flow entries in a flow table as many as possible, we can increase the flow entry matching rate.

Study on coupling of software-defined networking and wireless sensor networks

Typically, wireless sensor networks (WSNs) provide application-specific networking schemes based on restricted resources. For the reasons, WSN-based routing algorithms can be variously designed for applications. Even if two different WSN applications (e.g., target tracking and temperature monitoring) coexist in a network, the two applications can use different routing algorithms, running simultaneously on the same sensor nodes and network. However, the sensor nodes can efficiently spend their restrict resources (e.g., battery power) unless the two algorithms need to run simultaneously. There are a few research tries to deal with this problems by combining sensor networks with basic concepts of software-defined networking (SDN). However, performance of such a combination needs to be fully evaluated because the basic concept of SDN could not always give a positive effects to WSNs. Thus, this paper gives a try to analyze coupling of SDN and WSNs.

Scheme to guarantee IP continuity for NFC-based IoT networking

The key idea of IoT services and technologies is connectivity among all kinds of devices. The devices of the future would include very tiny things. Such a tiny device should support low-powered technology. However, the low-power technology could bring potential problems to device functions. This paper give a solution to overcome one of the problems for IoT devices based on NFC networking. NFC, which is from RFID technology, supports peer-to-peer communication on the link layer. Link addresses of NFC devices are not physically fixed values, so this give negative influences to IP networking; especially, connection continuity. Therefore, this paper gives a scheme to guarantee IP continuity for NFC-based IoT networking.

Enhanced Flow Table Management Scheme With an LRU-Based Caching Algorithm for SDN

We propose a flow table management scheme for OpenFlow switches to minimize table-miss in a flow table. Commercial OpenFlow switches have one or more flow tables that consist of flow entries for processing packets. However, flow entries are managed based only on their timeout parameters, meaning they are expired and deleted by switches regardless of their reusability. The absence of the flow entry then causes table-misses in the future. We propose a solution for the problem of switches disregarding vacancies in the flow table when deleting expired flow entries. When a table-miss occurs, the corresponding switch must perform additional interactions with an OpenFlow controller to insert new flow entries, but this results in additional processing time and communication overhead. Previous studies aimed at solving this limitation have used sophisticated training sets or modified network architectures. In contrast, we propose a simple flow table management scheme with a least recently used-based caching algorithm to keep flow entries in an OpenFlow switch as long as possible. For this purpose, the switch continually adjusts its cache size according to the vacancy of each flow table and the controller determines the packet forwarding path through the switches by referring to the vacancies. We perform an experimental evaluation of the proposed scheme and demonstrate the performance gains in terms of the number of table-missed packets. We also analyze the effectiveness of the flow entry caching scheme using a mathematical model.

Utilizing IP-over-NFC for Secure Data Transmissions: Demo Abstract

Near Field Communication (NFC) is a wireless communication technology using 13.56 MHz to support 2-way communications between two devices within ~10 cm. Such a short communication range may be considered as a shortcoming, but at the same time, this enables a secure data transfer within the connectivity region when compared to Bluetooth Low Energy (BLE) or Wi-Fi. Accordingly, NFC can be optionally utilized when secure data are transmitted in various services and applications focusing on ID validation. This demo presents a proof-of-concept for an alternative packet transmission method for achieving secure data exchange based on IP-over-NFC technology. For realizing this, there are a number of technical challenges. Utmost, the current NFC Linux kernel driver requires updates for supporting network-layer functionalities. Using such implementations, this demo demonstrates the procedures of transmitting secure data using NFC, while normal packet transmissions occur over WiFi simultaneously.

Performance analysis of degradation detection method on millimeter wave channel

The rapid proliferation of the high quality video service and the wide spread of the Internet of Things (IoT) are expected to create an unprecedented growth in mobile data traffic. To satisfy the requirements of these services, the communication system supporting very high data rate (Giga-bps) is required. The next evolution of the access technologies is currently being discussed as 5G to provide the innovative solution and to overcome the problem of frequency band shortage. Many companies and research institutes are carrying out preliminary studies of next-generation services and providing their outlook and requirements for the 5G service. These studies pointed out that the possibility of service disruption due to high propagation loss and block cause by an obstacle in the communication path is a challenging issue. This paper analyzes the performance of the current state detection algorithm to detect the signal blockage and examine the applicability of millimeter wave (mmWave) service.