Yool Kwon

Design and Implementation of an EPON Master Bridge Function in an ASIC

An EPON(Ethernet Passive Optical Network) master, slave chipset was developed. In EPON, LLID(Logical Link ID) value in the Ethernet frame’s preamble is used to make the PON look like a point-topoint links seen from the OLT(Optical Line Termination) and ONUs. This paper describes the functions and implementation of an EPON bridge in the master chip which performs bridge function for the upper network port and many lower PON logical ports differentiated by LLID. This bridge also has VLAN(Virtual LAN)-LLID mapping function to make the PON appear as many VLANs seen from the network port. It is also possible to define many VLANs for each ONU. It also has multicast pruning function through which only registered multicast traffic is sent downstream to destined ONUs.

Optical supervisory channel subsystem for 1.6T WDM transmission system

The optical supervisory channel (OSC) in WDM (Wavelength Division Multiplexing) transmission systems is used for OAM (Operations, Administrations and Management) function like overhead information in SOH (Synchronous Digital Hierarchy). We present supervisory information contents and alarm propagation procedure in our 1.6T WDM transmission system. Also, this paper describes the OSC frame structure and the OSC subsystem configuration that can provide reliable and effective operation and maintenance capability.

The Design of Key Security in Ethernet PON

This paper presents a method of key security in EPON. There are many keys between an OLT and many ONUs for encrypt and decrypt upstream/downstream data. To provide security in EPON, these keys should be make secure on generating, distributing, and updating. This paper designs a key security method that uses simple protocol without use of a secure channel and has no effect on normal data traffics

Simple Measurement Technique of the Cross Phase Modulation in Optical Fibers Using Heterodyne Detection Technique

We present a simple measurement technique of the cross phase modulation in optical fibers. A pump laser generates a new optical component (Stokes wave) in a probe optical wave with the modulation frequency of a pump laser. We investigated optical heterodyning between the probe optical wave and the Stokes wave, which allows one to generate and evaluate a beat signal in the lower frequency range. With the probe optical wave including the Stokes wave, the cross phase modulation signal can be measured in the pump laser modulation frequency to the tens of kHz range.

Hybrid self-healing mechanism with VP priority and dynamic bandwidth assignment policy in ATM networks

It is reasonable to restore the VP failures according to the VP priority level in respect of guaranteeing the QoS which is coupled with the VP priority. This paper proposes a new hybrid self-healing mechanism based on the VP priorities over the ATM networks. Backup VPs are assigned to restore the failures on the restoration domains such as the OAM segment or end-to-end VPC. Semi-dynamic VP restoration algorithms are used for the VPs which do not have backup VPs or whose backup VPs fail. The simulation results show that the proposed algorithm can restore higher priority VPs faster than the lower priority VPs.

Rate-based traffic scheduling algorithm based on load measurement in ATM network

ATM switches should be able to control various kinds of traffic that require different levels of service quality. Generally, ATM switches prepare per-class buffers in line interface circuits or in the switch fabric, and schedule them to satisfy the service requirements. This paper proposes a traffic control algorithm for ATM switches that combines a rate-based cell-scheduler and switch load measurement. Our method generates test cells for each traffic connection, and measures the test cells entering interval and exiting interval to estimate the switch load. By estimation the switch load, we determine the scheduling rate of each connection. We also propose a rate-based cell-scheduling algorithm. Computer simulations have evaluated the proposed algorithms. Our method can be used to accommodate ABR, VBR, UBR, and future GFR services.

A partial shaping mechanism for ATM networks

We propose a partial shaping mechanism (PSM) built upon the continuous-state leaky bucket (LB) mechanism which can control the shaping delay and the output buffer size. We assume that input traffic of the proposed shaping mechanism is the worst case traffic tolerated by the continuous-state LB mechanism and characterize traffic patterns that can depart from our shaping mechanism. We also compare shaping delay and output buffer size of the proposed shaping mechanism with the existing shaping mechanism which holds peak emission time strictly. Our results show that the proposed shaping mechanism can easily manage the shaping delay and the output buffer size than other mechanisms.