• Journal of IKEEE
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• v.18 no.3
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• pp.427-434
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• 2014

The Multihop Routing of vehicle communication environment is difficult to maintain due to heavy fluctuation of network topology and routing channel according to the movement of the vehicle, road property, vehicle distribution. We implemented GeoNetworking on the basis of ETSI(European Telecommunication Standard Institute) to maintain the vehicle safety service. GeoNetworking has its own way that delivers the data through the Unicast and Broadcast. In this paper, we compared performance index such as packet delivery ratio, end-to-end delay about GeoNetworking using the QualNet Network Simulator. Previous research assessed performance of GeoUnicast. This research has been additionally performed about GeoBroadcast, and we progressed algorithm performance through the comparison of CBF(Contention based Forwarding) of GeoUnicast with Greedy forwarding of GeoBroadcast.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5B
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• pp.378-389
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• 2006

An IP address lookup scheme has become a critical issue increasingly for high-speed networking techniques due to the advent of IPv6 based on 128bit. In this paper, a novel global IPv6 unicast address lookup scheme is proposed for next generation internet routers. The proposed scheme perform a variable multiple hashing based on prefix grouping. Accordingly, it should not only minimize overflows with the proper number of memory modules, but also reduce a memory size required to organize forwarding tables. It has the fast building and searching mechanisms for forwarding tables during only a single memory access. Besides, it is easy to update forwarding tables incrementally. In the simulation using CERNET routing data as a 6bone test phase, we compared the proposed scheme with a similar scheme using a uniform multiple hashing. As a result, we verified that the number of overflows is reduced by 50% and the size of memory for forwarding tables is shrunken by 15% with 8 tables.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.6
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• pp.1096-1101
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• 2004

By a tremendous expansion of Internet users, there's a number effects that cause the phenomenon of bottlenecked switching packets from routers. In order to tear down this problem, distributed system is applicable to almost every highly performed router systems. The main processor of distributed system, which manages routing table, commands IPC to delivering the forwarding table line processor that eases functionalities of the router. This makes the system having wired-speed forwarding function based on the hardware so that the performance of the network can be enhanced. Therefore, IPC, which assign a part of router, is necessary to exchange data smoothly and the constitution of IPC using Ethernet is widely adapted as a method for saving investment. In this paper, R-IPC mechanism improve the packet-processing rate over 10% through changed from defect of conventional Ethernet IPC, that is, 2 layer processing to TCP/IP or UDP/ IP into 1 layer processing for efficient packet forwarding.

• IEMEK Journal of Embedded Systems and Applications
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• v.5 no.4
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• pp.243-253
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• 2010

Multihop data delivery in vehicular ad hoc networks (VANETs) suffers from the fact that vehicles are highly mobile and inter-vehicle links are frequently disconnected. In such networks, for efficient multihop routing of road safety information (e.g. road accident and emergency message) to the area of interest, reliable communication and fast delivery with minimum delay are mandatory. In this paper, we propose a multihop vehicle-to-infrastructure routing protocol named Vertex-Based Predictive Greedy Routing (VPGR), which predicts a sequence of valid vertices (or junctions) from a source vehicle to fixed infrastructure (or a roadside unit) in the area of interest and, then, forwards data to the fixed infrastructure through the sequence of vertices in urban environments. The well known predictive directional greedy routing mechanism is used for data forwarding phase in VPGR. The proposed VPGR leverages the geographic position, velocity, direction and acceleration of vehicles for both the calculation of a sequence of valid vertices and the predictive directional greedy routing. Simulation results show significant performance improvement compared to conventional routing protocols in terms of packet delivery ratio, end-to-end delay and routing overhead.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12C
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• pp.1188-1193
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• 2007

This paper proposes a secure data forwarding scheme on source routing-based ad-hoc networks. The scheme uses two hash-key chains generated from a trusted third party to generate Message Authentication Codes for data integrity The selected MAC keys are delivered to the ad-hoc node using a pre-shared secret between the trusted third party and a node. The proposed scheme does not require the PKI, or the provisioning of the pre-shared secrets among the ad-hoc nodes.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3587-3594
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• 2022

A distributed high-speed data acquisition and monitoring system for the RF negative ion source at Huazhong University of Science and Technology (HUST) is developed, which consists of data acquisition, data forwarding and data processing. Firstly, the data acquisition modules sample physical signals at high speed and upload the sampling data with corresponding absolute-time labels over UDP, which builds the time correlation among different signals. And a special data packet format is proposed for the data upload, which is convenient for packing or parsing a fixed-length packet, especially when the span of the time labels in a packet crosses an absolute second. The data forwarding modules then receive the UDP messages and distribute their data packets to the real-time display module and the data storage modules by PUB/SUB-pattern message queue of ZeroMQ. As for the data storage, a scheme combining the file server and MySQL database is adopted to increase the storage rate and facilitate the data query. The test results show that the loss rate of the data packets is within the range of 0-5% and the storage rate is higher than 20 Mbps, both acceptable for the HUST RF negative ion source.

• The KIPS Transactions:PartA
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• v.11A no.2
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• pp.129-142
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• 2004

As the Internet gets faster, the demand for high-speed routers that are capable of forwarding more than giga bits of data per second keeps increasing. In the previous research, Bitmap Trie algorithm was developed to rapidly execute LPM(longest prefix matching) process which is Well known as the Severe performance bottleneck. In this paper, we introduce a novel algorithm that drastically enhanced the performance of Bitmap. Trie algorithm by applying three techniques. First, a new table called the Count Table was devised. Owing to this table, we successfully eliminated shift operations that was the main cause of performance degradation in Bitmap Trie algorithm. Second, memory utilization was improved by removing redundant forwarding information from the Transfer Table. Lastly. the range of prefix lookup was diversified to optimize data accesses. On the other hand, the processing delays were classified into three categories according to their causes. They were, then, measured through the execution-driven simulation that provides the higher quality of the results than any other simulation techniques. We tried to assure the reliability of the experimental results by comparing with those that collected from the real system. Finally the Enhanced Bitmap Trie algorithm reduced 82% of time spent in previous algorithm.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.213-216
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• 2000

In this paper, we propose a new scheme which improves the IP address lookup time. The new scheme is composed of two core technologies, named the prefix alignment and the prefix distance ordering. Now, as the Internet is being used commonly by improving the data transmission capacity, the need for enlarging the bandwidth of the Internet is on the rise. IP address lookup performance problem is an important obstacle in the router executing high speed packet forwarding. This results from the fact that the prefixes routing table is composed of and the traffic being processed in unit time are largely on the increase. The proposed lookup scheme is divided into two parts in technology, the one is the algorithm forming a routing database(routing table), the other is the lookup procedure in the actual packet processing.

• IEMEK Journal of Embedded Systems and Applications
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• v.14 no.4
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• pp.165-175
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• 2019

Networks use relatively slow heartbeat mechanisms, usually in routing protocols, to detect failures when there is no hardware signaling to help out. The time to detect failures available in the existing protocols is no better than a second, which is far too long for some applications and represents a great deal of lost data at 10 Gigabit rates. We compare the convergence time of routing protocol applying Bidirectional Forwarding Detection (BFD) protocol in wired mesh network topology. This paper suggests the combinations of protocols improving fail-over performance. Through the performance analysis, we contribute to reduce convergence time when system is fail-over.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.177-180
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• 2011

In practice, it is well known that geographical and/or location based routing is highly effective for wireless sensor network. Here, electing some landmarks on the network and forwarding data based on the landmark is one of the good approaches for a vast sensing field with holes. In the most previous works, landmarks are elected without considering the residual energy on each sensor. In this paper, we propose an Energy aware Landmark Election and Routing (ELER) protocol to establish a stable routing paths and reduce the total power consumption. The proposed protocol makes use of each sensor's energy level on electing the landmarks, which would be utilized to route a packet towards the target region using greedy forwarding method. Our simulation results illustrate that the proposed scheme can significantly reduce the power dissipation and effectively lengthen the lifetime of the network.