The document discusses light trees, which are used in wavelength routed optical networks employing wavelength-division multiplexing (WDM). A light tree enables single-hop communication from a source to multiple destinations using a minimum number of opto-electronic devices. It supports unicast, broadcast, and multicast traffic. Light trees can increase network throughput and provide high bandwidth communication over long distances for applications such as videoconferencing and internet television.

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2. CCoonntteennttss
• Introduction
• TDM and WDM
• Types of WDM
• Comparisons of CWDM and DWDM
• Light Path & Light Tree
• Architecture of Light Tree
• Unicast, Broadcast & Multicast Traffic
• Combining Unicast & Multicast Traffic
• Applications
• Advantages and Disadvantages
• Conclusion
• References

3. IInnttrroodduuccttiioonn
• The concept of light tree is introduced in a
wavelength routed optical network which
employs wavelength -division multiplexing
(WDM).
• Point to multipoint
• Enables single-hop communication
• Increases the network throughput.

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• Coarse Wavelength Division Multiplexing (CWDM)

7. • Dense Wavelength Division Multiplexing (DWDM)

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Feature CWDM DWDM
Wavelength
per fibre
8 – 16 40 – 80
Wavelength
spacing
2500GHz
(20nm)
100 GHz
(0.8nm)
Wavelength
capacity
Up to 2.5
Gbps
Up to 10 Gbps
Aggregate
fibre capacity
20–40 Gbps 100–1000
Gbps
Overall cost Low Medium

9. LLiigghhtt PPaatthh
• A light path is an all-optical channel, which may
be used to carry circuit switched traffic and it may
span multiple fiber links. Assigning a particular
wavelength to it sets these up.
• A major objective of light path communication is
to reduce the number of hops a packet has to
traverse.

10. Architecture Of Light Tree

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These are the types of transmissions
used in Light Tree:
• Unicast Traffic
• Broadcast Traffic
• Multicast Traffic

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17. AApppplliiccaattiioonnss
 Teleconferencing
 Videoconferencing
 Internet NEWS distribution
 Internet television etc..

18. AAddvvaannttaaggeess
• Data Security
• Ease of installation
• Eliminating Spark Hazards
• High Bandwidth over Long Distances

19. DDiissaaddvvaannttaaggeess
• Price
• Fragility
• Opaqueness
• Requires special skills

20. CCoonncclluussiioonn
• WDM WAN architecture based on light trees is
capable of supporting broadcasting and
multicasting over a wide-area network by
employing a minimum number of opto-electronic
devices.
• WDMWAN can provide a very high bandwidth
optical layer, which efficiently routes unicast,
broadcast and multicast packet-switch traffic.

21. • http://studentstable.com/light-tree/
• http://www.ietf.org/proceedings/50/slides/ipo-
7/sld006.htm
• http://www.scribd.com/doc/7149001/Light-Tree
• http://www.scribd.com/doc/52583313/light-tree
• http://ieeexplore.ieee.org/stamp/stamp.jsp?
tp=&arnumber=747251
• http://link.springer.com/chapter/10.1007%2F0-
387-29188-1_12