In the management of Internet Protocol networks, the number of flows is an important performance metric because it has useful applications in areas such as port scan detection, denial-of-service detection, and traffic analysis. Real-time counting of flows is particularly important because network operators can take immediate actions against detected network anomalies or performance degradation. This paper presents a method that enables real-time counting of flows classified by application. More useful information for network management can be obtained by counting classified flows. For example, the proposed method is helpful in determining the type of attacks or victim services for attack detection. The algorithm for counting classified flows is developed using the timestamp vector algorithm. This paper first explores a naïve method that has as many timestamp vector mechanisms as the application classes. However, this method is disadvantageous because it consumes very large memory space. To avoid this problem, a new method that considerably decreases memory consumption is proposed. In addition, the paper also investigates a method for improving measurement accuracy. The effectiveness of the proposed method is evaluated for real-world network data.

For the management of IP (Internet Protocol) networks, flow counting is significant because of various applications such as denial-of-service (DoS) attack detection, etc. Although several flow counting algorithms have been proposed in literature, they have disadvantages in computational time and accuracy. This paper proposes a flow counting algorithm that eliminates these disadvantages. The proposed method improves the computational time through two techniques: packet sampling and a new data structure based on multiple counters. For the accuracy, the existing flow counting methods is often degraded by regarding the terminated flows as existing and thus overestimating the number of flows. The paper examines a method that avoids such overestimation by utilizing TCP FIN messages. The effectiveness of the proposed method was evaluated and compared with an existing method experimentally.

The accuracy and precision of time synchronization in Ethernet must be enhanced since Ethernet is becoming a critical component of telecommunication networks. This paper investigates a precise time synchronization technique that supports Gb/s Ethernet. To obtain accurate time synchronization, delay variation in message transfer and processing must be minimized. For this purpose, the paper first describes an implementation of preemptive priority queuing, which decreases the message delay variation of Ethernet. The paper then proposes a time synchronization method that is performed in the lower protocol layer and then describes its implementation on FPGA-based hardware. The proposed method achieves superior time accuracy and precision through the low message transfer/processing delay variation provided by preemptive priority, lower layer execution, and hardware implementation. The effectiveness of the method is confirmed through experiments.

The virtual path concept has several valuable features to construct an economical and efficient asynchronous transfer mode (ATM) network. One of them is bandwidth control which affords transmission efficiency improvement through statistical sharing of capacity. An effective bandwidth control algorithm and its calculated performance are described. Network performance with the algorithm is evaluated, and the bandwidth control is shown to successfully improve network transmission efficiency with only a slight increase in processing load compared to the fixed bandwidth scheme. A method is also proposed to equalize call loss probability for each virtual path. The effectiveness of the method is demonstrated by analysis.>

Broadband transport techniques and network architectures based on the virtual path concept are examined. ATM (asynchronous transfer mode) techniques, when coupled with recent technological innovations, are expected to pave the way for future universal transport networks. The virtual path concept, which exploits the ATM's capabilities, is proposed to construct an efficient and economic network. The concept matches current and anticipated technological trends well. Characteristics and implementation techniques of virtual paths are discussed. Advantages of the virtual path concept and its impact on the transport network architecture are demonstrated. The virtual path strategy is also shown to provide efficiently for networks with dynamic reconfiguration capability which will enhance network performance. Some basic analytical results on the dynamic control effects of virtual paths are provided.>

A simple control algorithm is proposed for a three-stage rearrangeable switching network with time division multiplexed links. The nonblocking condition is shown for the rearrangeable network controlled by the proposed algorithm. The rearrangeable nonblocking network controlled by the proposed method is more cost effective in hardware than a strictly nonblocking network for a large number of channels multiplexed on links. The computing complexity of the algorithms is not more than that for controlling the strictly nonblocking network. In the proposed algorithm, only one path must be moved in the rearrangement, thus reducing the difficulty in implementing the rearrangeable network. This algorithm is efficient for broadband switching systems or cross-connect devices where nonblocking switches are needed.