On the Multicast Scheduling Mechanism for Interconnected WDM Optical Networks Student ： Tse Hsien Lin Teacher ： Ho-Ting Wu Date ：

Outline Motivations The Single Optical Star Network Architecture The Proposed Multicast Algorithms The Dual-Star Optical Network Architecture and the Associated Scheduling Mechanisms The Arrayed-Waveguide Grating-Based Single- Hop WDM Network Architecture Conclusions Reference

Motivations Network Environments  WDM Optical Star Networks  Packet Switched  Multicast Transmission To Design a Multicast Scheduling Algorithm  Simple  Efficient  Scalable

Optical Star Network Architecture Network Node  Data Channels – TT,TR  Control Channels – FT,FR Central Scheduler/Controller

A Central Scheduler/Controller One Input Queue for Each Source Node Executing Multicast Scheduling Algorithms in a Slot-by-slot basis

Slotted OP for Asynchronous Network The Schedule Keeps Track of the Ranging Info. Network Nodes Remain Asynchronous

Multicast Scheduling Mechanisms The Optimum Scheduling Algorithm Should  Optimize Wavelength Channel Usage, Receiver Utilization Level, Packet Transmission Delay Complicated and Hard to Find Heuristic Mechanisms  Starting with Randomly Selecting One Input Queue  Partitioning packets, if Necessary  An All-out Packet Is Defined to Be a Queued Packet with All of Its Intended Recipients Free at the Scheduling Time

Multicast Scheduling Algorithms – Previous Works Persistent Scheme  The Head of Line Packet Persists in Occupying the Channel Continuously Until All of its Recipients Receive the Packet  The Head of Line (HOL) Blocking Problem Random Scheme  HOL Partitioned Packet to a Random Position  Packet Transmission Delay May Increase

Persistent Scheme  HOL Message Persists in Occupying the Channel  The Head of Line (HOL) Blocking Problem Multicast Scheduling Algorithms – Previous Works

 Random Scheme  HOL Partitioned Packet to a Random Position  Packet Transmission Delay May Increase

Proposed Multicast Scheduling Algorithms – LBQA Search for an All-out Packet in the Input Queue up to the Lookback Length L Send the AII-out Packet, Otherwise Send the Partitioned HOL Packet

Proposed Multicast Scheduling Algorithms – LBRA Search for the Max Ratio Packet within the Lookback Length L of the Input Queue, and then Send the Packet Ratio = (The Number of Free Recipients of the Packet) / (The Number of All Recipients of the Packet)

Proposed Multicast Scheduling Algorithms – DCHA Loop (1): Search for and Send the HOL All-out Packets among All Queues Loop (2) Partition and Send Remaining HOL Packets

Proposed Multicast Scheduling Algorithms – DCHA (Conti.)  Loop (2): Partitioning and sending remaining HOL Packets

Performance Evaluations Simulation Parameters  N:Number of Network Nodes  W:Number of Wavelength Channels  K:Multicast Size, a Random Variable  L: Lookback Length for LBQA and LBRA Schemes  T:The average number of transmissions required per packet  Max(E[K]xW/N,1):Theoretical Lower bound of average number of transmissions required per packet

Efficiency versus W/N for different lookback Lengths (L) for the LBQA Scheme Performance Results

Efficiency versus W/N of Three Traffic Models for the LBRA Protocol

Efficiency Comparisons for Different Unicast Ratios Performance Results

Efficiency of three Traffic Models for Three Protocols

Efficiency versus W/N for 5 multicast Protocols Performance Results

The Dual-Star Network Architecture Two Star Couplers Bridged by Two TBPFs  The passband of each TBPF is adjusted at every slot Channel Allocation Schemes  Two inter data channels: A->B; B->A – dynamically adjusted  Intra data channels: A->A; B->B – wavelength reuse

Schematic Diagram of the Dual-Star Network Channel Allocation Schemes  Two Inter Data Channels: A->B; B->A – Dynamically Adjusted  Intra Data Channels: A->A; B->B – Wavelength Reuse

Dynamically Adjust TBPF B -> A Assignment Intra Data Channels B -> B Assignment Intra Data Channels B -> B Assign Inter Data Channels B -> A Assign Inter Data Channels B -> A Dynamically Adjust TBPF A -> B Assign Intra Data Channels A ->A Assign Intra Data Channels A ->A Assign Inter Data Channels A -> B Assign Inter Data Channels A -> B Wavelength Reuse for AWavelength Reuse for B The Multicast Algorithms for the Dual Star Network Channel Assignment Procedure per slot Star AStar B Central Scheduler

The Efficiency of DS-LBQA versus LBQA Performance Results for the Dual Star Architecture

Efficiency Comparisons for three Mechanisms

Channel Assignment for the Dual-Star Network The Number of Wavelength Channels W=36

The Arrayed-Waveguide Grating-Based Single- Hop WDM Network Architecture Every node uses one fiber for transmission and the other fiber for reception. In order to distinguish data and control information, we employ direct sequence spread spectrum techniques. By using multiple spreading codes, several nodes could transmit their control packets at the same time, leading to code division multiple access (CDMA).

The AWG Multicasting With Spatial Wavelength Reuse Every second wavelength is routed to the same output port. This period of the wavelength response is called free spectral range (FSR). Each splitter equally distributes all incoming wavelengths to all attached receivers.

Timing Structure

M slot, control packets are transmitted and all nodes tune their receivers to one of channel in order to obtain the control information Control packets are sent on a contention basis using a modified version of slotted ALOHA.

Conclusions Proposed three Multicast Scheduling Mechanisms for Single Optical Star Networks Outperform Previous Works for Most Scenarios Proposed the Dual-Star Network Architecture and the Corresponding Multicast Schemes  Inter Data Channels; Intra Data Channels  Wavelength Reuse Property  Achieving Better Performance Results than Those from Single Star Networks, When the Number of Network Nodes Is Large ( i.e. W/N is small)

Reference “On the Multicast Scheduling Mechanisms for Interconnected WDM Optical Networks” Ho-Ting Wu, Po-Hsin Hong, Kai-Wei Ke “Design and Analysis of an Asynchronous WDM Local Area Network Using a Master/Slave Scheduler” Eytan Modiano, Richard Barry “Random Algorithms for Scheduling Multicast Traffic in WDM Broadcast-and- Select Networks” Eytan Modiano