Sun-Sik Roh

Security model and authentication protocol in EPON-based optical access network

An EPON (Ethernet passive optical network), which is progressing to standardization in IEEE 802.3ah, consists of an OLT (optical line termination) and multiple ONUs (optical network units) using passive optical components. This network is susceptible to various security threats, such as eavesdropping, masquerading, denial of service, and so on. We propose a security model and a security protocol to support authentication in an EPON based optical access network. We analyze security threats and security models in the EPON reference model. After considering these models, we propose that an encryption layer is placed at the RS layer. The paper proposes an authentication protocol based on public key exchange and a key establishment protocol. User authentication and ONU authentication are performed separately to give efficient key management and a strong authentication service.

Design of Authentication and Key Exchange Protocol in Ethernet Passive Optical Networks

An EPON has security threats because it is a broadcast architecture that consists of one OLT and multiple ONUs. So the EPON needs strong security services of authentication, confidentiality and access control. In this paper, we analyze general and EPON-specific threats and propose an authentication and key exchange protocol based on the public key mechanism. We design the security protocol in EPON MAC layer for reducing the overhead of security service. User authentication and ONU authentication are performed separately for efficient key management and strong authentication service. We design the efficient key exchange protocol using derived session key by exchanging the random number. The proposed protocol is verified in the view of known key secrecy, key compromise impersonation, explicit key authentication and unknown key-share.

Offset Time Decision (OTD) Algorithm for Guaranteeing the Requested QoS of High Priority Traffic in OBS Networks

In this paper, we propose the Offset Time Decision (OTD) algorithm for supporting the QoS in optical networks based on Optical Burst Switching (OBS), which is the new switching paradigm, and evaluate the performance of the OTD algorithm. The proposed algorithm can decide a reasonable offset time to guarantee the Burst Loss Rate (BLR) of high priority traffic by considering traffic load of network and the number of wavelengths. In order to design this effective OTD algorithm, firstly we illustrate the new burst loss formula, which includes the effect of offset time of high priority class. As the decision of offset time corresponding to the requested BLR, however, should use the reversed formula of new one, we are not able to use it without any changes. Thus, we define the Heuristic Loss Formula (HLF) that is based on the new burst loss formula and the proportional equation considering its characteristics. Finally we show the OTD algorithm to decide the reasonable offset time by using HLF. The simulation result shows that the requested BLR of high priority traffic is guaranteed under various traffic load.

Design and Performance Evaluation of Traffic Grooming Algorithms in WDM Multi-Ring Networks

In this paper, we propose novel traffic grooming algorithms to reduce the cost of the entire system in WDM multi-ring networks. In order to achieve this goal, it is important to construct a virtual topology and groom the traffic in these networks. We consider four kinds of virtual topologies of WDM multi-ring networks according to the way in which traffic is transmitted among rings. Accordingly, we design four kinds of traffic grooming (TG) algorithms depending on the considered virtual topologies: mixed (MTG), partially mixed (PMTG), separate (STG), and independent (ITG) traffic grooming algorithms. Each algorithm consists of a separation, a connection-ring construction, and a grooming procedure. In the separation procedure, all traffic connections are classified into intra and inter-connections. The connection-ring construction procedure makes full connection-rings from traffic connections. The grooming procedure groups connection-rings onto a wavelength in order to reduce the number of SONET add/drop multiplexers (SADMs) and wavelengths and to improve the utilization of network resources. To analyze the performance of each algorithm, a circular multi-ring architecture with uniform traffic is considered. The simulation results show that ITG and PMTG are more efficient in terms of wavelengths. STG and PMTG require a smaller number of SADMs.

QoS Supporting Algorithms for Optical Internet Based on Optical Burst Switching

In this paper, we propose a protocol architecture and quality of service (QoS) supporting algorithms for optical Internet based on optical burst switching (OBS) technology. Firstly, the function of each layer of the protocol architecture and the formats of control packets are defined in order to adopt GMPLS to the control plane of OBS. Then, the offset time decision (OTD) algorithm to cooperate with the proposed protocol architecture is designed for optical Internet. A new burst loss formula taking into account the effect of offset time is introduced to design the OTD algorithm. This algorithm can decide on the appropriate “priority-offset” time according to the required QoS by using the reversed equation of the so-called heuristic loss formula (HLF) which is approximated as a proportional equation of our new loss formula. Finally, we propose a CAC algorithm based on the OTD algorithm for the purpose of increasing the availability of wavelength resources and supporting the QoS of established connections in optical Internet. The performance of the proposed algorithms is evaluated in terms of burst loss rate and the number of connections through simulation.

Design and Performance Evaluation of a Separated Control Signaling Protocol for WDM Optical Networks

In WDM optical networks, an efficient control signaling protocol is required to dynamically establish lightpaths. This paper proposes a separated control signaling protocol (SCSP) and compares the performance of SCSP with a conventional integrated control signaling protocol (ICSP). The conventional ICSP makes reservations sequentially from the source to the destination for setting up and tearing down lightpaths. It increases the control overhead and wastes the network resource if it cannot reserve the network resource at an intermediate node. Specifically, if the receiver at the destination is not available after successful reservation at intermediate nodes, it wastes a lot of bandwidth. It causes decreasing chances of reservation for other lightpaths. Instead, SCSP separates bearer control from call control to reduce the waste of network resources. The call control function checks the availability of network resources such as wavelengths and receivers. Bearer control reserves, allocates, and releases network resources. To evaluate the performance of the two protocols, they are mathematically analyzed using a probabilistic model. Simulation results are also provided to compare the proposed protocol with the conventional ICSP in terms of utilization and blocking probability. From the results of simulation and iterative analysis, we can observe that SCSP performs better than ICSP.