Multimedia applications and Optical networks

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Multimedia applications and Optical networks

• Sitaram Asur, Sitha Bhagvat,
• Mohammad Kamrul Islam ,Rajkiran Panuganti 

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Overview

• Optical Networks - Advantages Overheads
• Requirements of Multimedia Applications
• Issues
• Protocol level
• Network level
• Scheduling QoS
• Circuit switching
• OBS
• OLS

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Optical Networks

• Can provide very high bandwidth ( gt 20TB/s per
  fiber)
• Traditional optical networks are circuit switched
• Transition to packet switched
• Wavelength Div Multiplexing (WDM) or TDM
• Multiparty communication possible required in
  multimedia appl.
• Not easy to integrate with current Internet
• No efficient O/E or E/O conversion is present.
• No Optical RAM ? no buffering

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WDM (Wavelength Div Multiplexing)
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The challenge of multimedia

• Support for continuous media
• Quality of service management
• Packet Delay delay sensitive
• Jitter
• Bandwidth
• Packet-loss ratio guarantee
• But, loss tolerant
• Multiparty communication
• Requires multicast support
• Different requirement of QoS

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Protocols

• Traditional Protocols like TCP cannot utilize all
  the available Bandwidth
• New Protocols - Fast, Fair, Friendly
• High utilization of the abundant bandwidth
• Intra-protocol fairness
• TCP friendly
• Common Issues solved by New Protocols
• Acknowledgement
• Congestion control
• Bandwidth Estimation necessary to utilize it
  efficiently

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UDT (UDP-based Data Transport)

• Acknowledgement
• UDT uses timer-based selective acknowledgement
• Congestion control
• AIMD - Does not meet efficiency objective
• UDT uses modified AIMD algorithm to use 90 of
  the available Bandwidth
• Bandwidth Estimation necessary to utilize it
  efficiently
• Link capacity estimation and available BW
  estimation
• UDT uses packet-pair method for bandwidth
  estimation
• Avoiding Congestion collapse
• Cause - from increasing control traffic - costs
  both substantial BW and CPU time
• Occurs if processing time is large
• UDT increases expiration time to avoid congestion
  collapse

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Scheduling in Circuit Switching

• Scheduling necessary for high bandwidth
  utilization in Lambdas
• Circuit switched networks fixed bandwidth
  allocation
• Fixed bandwidth allocation ? low bandwidth
  utilization
• Solution Use knowledge of data sizes to
  schedule calls
• What rate should network assign for a particular
  transfer?

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Varying-Bandwidth List Scheduling (VBLS)

• Input
• Known data size
• Maximum bandwidth limit
• Desired start time
• The scheduler returns a time-range capacity
  allocation vector assigning varying bandwidth
  levels in different time ranges for the transfer

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VBLS
Available time ranges
Shared single link
S1
Circuit Switch
Ch. 1
D
TRC1
Ch. 2
S2
Ch. 3
TRC2
Ch. 4
S3
t1
t2
t3
t4
t5
TRC3
4
3
2
1
time
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Advantages of VBLS

• Time-Range-Capacity vector allocation for vectors
• Allows Scheduler to backfill holes
• VBLS allows users to take advantage of subsequent
  availability of network
• VBLS better than Packet Switching in ease of
  implementation, management of pricing mechanisms
  for resource allocation
• Disadvantage need to reprogram the circuit
  switch multiple times

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Evolution of Optical Networking
Optical Provisioning, Reconfiguration, and
Switching Strategies
Highly Dynamic
Optical Label/Burst Switching
Dynamic Reconfigurable Optical Networks
Network Efficiency
Reconfigurable Optical Networks

• Addresses carrier needs
• Bandwidth utilization
• Provisioning time
• Scalability

Static
Point-to-Point Optical Transport
Present
Future
Past
RHK Carrier Survey
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Next Generation Optical Network

• IP over all-optical Wavelength Division
  Multiplexing (WDM) layer

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Optical Burst Switching (OBS)

• Combines the best of packet and circuit switching
  and avoid their shortcomings.
• First a control packet is sent using a separate
  (control) channel (wavelength).
• Configure the intermediate node and reserves BW.
• Without waiting for the reservation ACK, data
  burst follows the control packet but using
  different channel.

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How OBS works

• At ingress Edge router E/O conversion occurs.
• At Edge router, IP packets are assembled into a
  data burst.
• From Edge router, Control packet sent to Core
  router to setup a path
• Data burst sent in the same path using different
  wavelength.

3 Switch Configuration
4 Burst forwarding
Edge Router (NY)
Legacy Interface (IP)
1 Burst assembly
Edge Router (CA)
Legacy Interface (IP)
5 Burst disassembly
2 Control packet
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Scheduling at OBS Core

• Two basic scheduling algorithms
• LUAC ( Latest available unscheduled channel)

Fiber Delay Lines (FDLs)
Illustration of LAUC algorithm, (a) channel 2 is
selected, (b) channel 3 is chosen.
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Scheduling at OBS Core

• LUAC is simple but inefficient channel usage due
  to gaps/voids.
• LUAC VF (LUAC with void Filling)

Illustration of LAUC-VF algorithm.
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Buffer allocation at Edge Router

• Buffering is required when creating a data burst
  by assembling the IP packets of same class.
• How long assembling continues till maximum
  threshold burst size or timeout.
• If finds available wavelength, send it.
• If not, the scheduler keeps the buffer till it
  gets an available channel or maximum buffering
  time .
• High priority packets have longer buffering time
  and hence experience less dropping.

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Bandwidth Allocation at Core Switch

• Bandwidth allocation of class N at time t Bn(t)
  Bandwidth allocation ratio Rn
• Higher priority packets has larger value of Fn
  and hence lower Rn.
• When a data burst of class X found no free
  channel at the output port
• Scheduler looks a channel with higher Rn value.
• It preempts that channel and schedule the burst
  of class X
• If no such channel is found, it drops the burst.
• Observations Multimedia applications with larger
  Fn have smaller dropping probability.

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OLS Optical Network
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Optical Label Switching (OLS)

• OLS enables packet switching and multiplexing in
  the optical domain
• Packet forwarding is based on an optical header
• Header is sub-carrier multiplexed with the
  optical data
• The label field in the optical header
  determines packet forwarding
• Data is delayed while the header is examined
• Routers erase and re-insert the label in the
  optical header
• Enable optical time slot switching and
  multiplexing in subwavelength domain independent
  of packet protocols
• No need for end-to-end network synchronization

Low Bit Rate Subcarrier Label
Label and Packet Forwarded
High Bit Rate Optical Packet
Fiber
Only low cost electronics required to process the
label in parallel
Optical Header Extraction Unit
Label Extracted for Processing
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Optical-Label Switching for Packet Routing
TDM Label
IP Data
IP Header
features
Label
Time
WDM Label
SCM
Label
features
WDM Wavelength li
IP Data
IP Header
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Advantages of OLS

• Only the optical label needs to be converted.
• Payload stays optical, which provides
  transparency to packet bit-rate and data format
• Enables dynamic optical switching and routing
  from the optical circuit to the packet level of
  granularity
• Convergence of both types to a single platform
• Routers can be shrunk to chip-sized elements that
  consume two to three orders of magnitude less
  power than their electrical counterparts
• Facilitates support for quality of service (QOS),
  class of service (COS) and traffic engineering.

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Applications

• Next Generation Internet
• Data exchange communications
• Virtual Private Networking (VPN)
• Analog/digital communications
• Voice over Internet Protocol (VoIP) and
• Broadcasting and video conferencing.

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Modern Features of OLS Routers

• Multicast contention resolution
• To support multicast of multimedia applications
• Optical Time to Live
• Weighted TTL - OSNR
• Label generation and packet classification
• based on QoS/CoS requirements

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Multicast Contention Resolution in OLS

• Multimedia conferencing and streaming are growing
  fast
• Multicast in router saves network resources
• Absence of optical logical circuits and buffers
  to generate copies
• Solution Extra ports on OLS core routers to
  handle multicast
• Port contains Multi-Wavelength Converter
• Contention resolution and arbitration a challenge
• Solution Multicast Contention Resolution
  Algorithm

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Multicast Contention Resolution
Sad
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Optical Time to Live

• OLS core routers monitor the OSNR of each packet
• The label signal quality is used to estimate the
  payload signal quality.
• OSNR degrades as the packet travels through OLS
  router hops and links.
• When the OSNR goes below a threshold, the router
  will drop the packet.

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Label generation and packet Classification

• OLS edge routers implement packet aggregation and
  label processing
• Edge routers provide different QoS/CoS policies
  to client applications.
• Label includes the packet length, CoS, source
  address, destination address etc.
• Edge routers at the end points de-aggregates the
  packets, classifies and maps the packets to
  different QoS policies.

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References

• Phuritatkul, J., Ji, Y., Buffer and Bandwidth
  Allocation Algorithms for Quality of Service
  Provisioning in WDM Optical Burst Switching
  Networks, Lecture Notes in Computer Science,
  Vol.3079, pp.912-920, 2004
• Qiao, C., Yoo, M., Dixit, S., OBS for Service
  Differentiation in the Next-Gen Optical Network,
  IEEE Commu. Magazine, Feb. (2001) 98-104
• Zhong Pan, Haijun Yang et al, Advanced
  Optical-Label Routing System Supporting
  Multicast, Optical TTL, and Multimedia
  Applications, IEEE Journal of Lightwave
  Technology, Vol 23, No 10, October 2005
• R. Ramaswami and K. Sivarajan, Optical Networks
  A Practical Perspective, Morgan Kaufmann
  Publishers, 1998
• B. Mukherjee, Optical Communication Networks,
  McGraw Hill, 1997

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• THANK YOU

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Helper Slides
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Helper - Raj