Differentiated Services Support in Optical Burst Switching WDM Networks

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Differentiated Services Support in Optical Burst
Switching WDM Networks

• David Q. Liu
• Dept. of Computer and Information Science
• The Ohio State University
• January 4, 2004

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Outline

• Optical Network
• Optical Burst Switching
• Differentiated Burst Scheduling
• Future Work

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Todays Internet

• Important and ubiquitous
• Rapid growth and bandwidth demand
• Relative slow electronic router and switch
  (bottleneck)
• Hardware based highspeed electronic router
• - Available soon (300 400 Gbps total)
• ATM switch 10 Gbps

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Optical Networks

• Why Optical Networks
• Huge bandwidth
• Possible 50 Tbps
• D-WDM technology 80-120 ?, 400 Gbps per fiber
• Low signal attenuation, distortion, power
  consumption, material usage, cost, and bit error
  rate 10-15.
• Small space requirement
• Current electronic routers or ATM switches can
  not handle huge bandwidth from optical fibers

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Optical Networks

• Optical network generations
• Wavelength routed networks -- current
• Optical burst networks short-term
• Optical packet networks future

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Optical Switching Techniques

• Wavelength Routed Switch
• Circuit based, not efficient
• Optical Burst Switch
• Electronic control processing optical data
  switching
• Optical Packet Switch
• Require optical random access memory for
  buffering (un-available)
• Use FDL (fibre delay line) to provide limited
  delays
• Stringent synchronization requirement
• Between packets arriving in different input ports
• Between packets header and its payload

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Switching Technologies Comparison

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Optical Burst Switching

• Combine IP packets with the same destination and
  similar QoS features into a data burst
• Assembling IP packets into a burst at ingress
  edge router
• Disassembling a burst into IP packets at egress
  edge router
• Send burst control packets (BCP) ahead of bursts
  to reserve resource in each intermediate
• node

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Optical Burst Switching

• Separate transmission and switching of the data
  burst and BCP
• Ingress-to-egress transparent optical path for
  the data burst
• Electronic processing of BCP
• BCP sent ahead to reserve resources in the
  switches and wavelength for next hop
• Separate control wavelengths/channels

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Optical Burst Switching Mechanism
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OBS WDM Network

Edge router
Interfaces to legacy system
WDM Link
BCP
Interfaces to legacy system
Data burst
Core router
Interfaces to legacy system
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Edge Router (Sending)
Flow direction
OBS Edge Router sending
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Edge Router (Receiving)

Switch
Burst Disassembler
Scheduler
Legacy Interfaces
OBS Interfaces
Burst Disassembler
Scheduler
Flow direction
OBS Edge Router receiving
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OBS Core Router

Routing Signaling Module
Scheduler Switch control
CC k ? DC K k ?
F D L
F D L
1
N
Space switch
OBS Core Router
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Differentiated Optical Burst Services

• IETF DiffServ
• provides service differentiation through
  supporting Per-Hop-Behavior with DS field in IP
  packet
• Differentiated Optical Burst Services (DOBS)
• DiffServ DS ? DOBS priority class (more
  efficient)
• Differentiated Burst Assembly and Scheduling at
  ingress edge nodes
• Differentiated scheduling at core nodes
• MPLS (Multi-Protocol Label Switching) provides
  OBS routes and traffic engineering
• Extended GSMP (General Switch Management
  Protocol) for OBS switch management

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Resource Reservation Burst Scheduling

• Resource Reservation
• Control packet processing / burst scheduling
• Dynamic Switch Fabric Configuration
• Burst Scheduling
• Find available wavelength for burst transmission
• Use burst info in control packet
• Offset time
• Burst length
• Priority
• Goal
• Maximize throughput
• Minimize burst loss probability
• Minimize burst delay
• Support QoS / Differentiated Services

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Existing DiffServ Support Techniques

• Prioritized Offset Time
• Extra offset time for high priority bursts
• Burst into segments, and prioritized dropping
• Burst assembly techniques with priority
• Deflection routing with priority

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My Approaches

• Priority-based scheme (PS)
• Differentiated scheduling scheme (DS)

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Differentiated Scheduling

• Control packets are queued according to their
  destination
• Round-robin scheduling among queues
• High priority control packets are processed more
  promptly than low priority control packets
• Priority classes from 1 (highest) to N (lowest)
• A class i control packet is processed after a
  differentiated processing delay (DPDi) upon its
  arrival

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Differentiated Scheduling

• Uniform DS (U-DS)
• DPDi (i 1) td for 1 lt i lt N
• td differentiated processing delay unit
• Non-uniform DS (N-DS)
• (0) DPD1 lt lt DPDN
• or
• for 2 lt i lt N
• td,j differentiated processing delay
  difference
• between class j and class j 1

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Differentiated Scheduling
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Priority Class Isolation

• Bounded burst service (transmission) time
• td max burst service time
• ?high priority class bursts are not
  blocked by lower priority class burst
• Exponential burst service (transmission) time
• td 5 times mean burst service time
• ?higher priority class blocked by any
  lower priority class less than 1 e5 0.0068

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Support Different of Classes

• Each node decides how many priority classes to
  support by choosing different delay difference
  between two adjacent classes
• Edge and Core Nodes
• Edge
• N classes with U-DS, processing delay unit td
• Core Node
• N odd (N1)/2 classes with U-DS, processing
  delay unit 2td
• N even N/2 1 classes with N-DS, n/2 1 of 2
  td ,
• and one td

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System Parameters and Variables
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Burst Loss Probability-- expo inter-arrival
expo burst length
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Burst Loss Probability-- expo inter-arrival
Pareto burst length
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Burst Loss Probability-- Pareto inter-arrival
expo burst length
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Burst Loss Probability-- Pareto inter-arrival
Pareto burst len
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Effect of DPD
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Loss Probability Control
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Loss Probability Control
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Loss Probability Control
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Loss Probability Control
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End-to-end Performance

• Goal
• Performance of DS
• Interflow impact
• Network design parameters

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Network Topology
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Traffic Routes
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System and flow variables
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Scheduling Queue Policy

• Four control packet processing queue policies
• Single queue per node SQ
• A queue per priority in a node PQ
• A queue per flow FQ
• A queue per priority and flow pair (random
  order) ROQ
• A queue per priority and flow pair (priority
  order) POQ
• A queue per priority and flow pair (flow order)
  FOQ
• A queue per priority and flow pair (total order)
  TOQ

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DS Network Performance
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DS Network Performance
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DS Network Performance
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DS Network Performance
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DS Network Performance
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DS Network Performance
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DS Network Performance
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Future Work

• Resource reservation fairness among different
  flows
• Better burst contention resolutions
• Better burst assembly mechanisms
• Security Optical Burst Switching Networks
• Control channel and packet security
• Data burst security

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Summary

• Optical Networks
• Optical Burst Switching
• Differentiated Scheduling
• Single node
• Network-wide
• Future Work