The document discusses light trees, which are point-to-multipoint optical channels that can span multiple fiber links, enabling single-hop communication between a source node and destination nodes. Light trees were first proposed in 1978 and allow WDM systems to combine multiple signals onto a single fiber. They increase network throughput by reducing hop distances in a wavelength routed optical network. Light trees can support unicast, multicast, and broadcast traffic and require multicast-capable wavelength routing switches at network nodes and additional optical amplifiers to maintain signal power over split signals. They provide benefits like high bandwidth, ease of installation, and data security but also have disadvantages regarding cost, fragility, and technical skills required.

1. Light TreeLight Tree
Presented By:Presented By:
Jitendra YadavJitendra Yadav
11BCAA4611BCAA46

2. Index
 IntroductionIntroduction
 HistoryHistory
 DefinitionDefinition
 Need ForTechnologyNeed ForTechnology
 ApplicationApplication && FunctionalityFunctionality
 Requirement of TechnologyRequirement of Technology
 AdvantagesAdvantages andand DisadvantagesDisadvantages
 Future enhancementFuture enhancement
 ConclusionConclusion
 ReferencesReferences
TreeTree

3. IntroductionIntroduction
o The concept of light tree is introduced in a
wavelength routed optical network which
employs wavelength -division multiplexing
(WDM).
o Point to multipoint
o Enables single-hop communication
o Increases the network throughput.
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4. HistoryHistory
o The concept was first published in 1978, and by 1980 WDMThe concept was first published in 1978, and by 1980 WDM
systems were being realized in the laboratory. The firstsystems were being realized in the laboratory. The first
WDM systems combined only two signals. Modern systemsWDM systems combined only two signals. Modern systems
can handle up to 160 signals and can thus expand a basiccan handle up to 160 signals and can thus expand a basic
1010 Gbit/sGbit/s system over a single fiber pair to over 1.6system over a single fiber pair to over 1.6 Tbit/sTbit/s..
o WDM systems are popular withWDM systems are popular with
telecommunications companiestelecommunications companies because they allow them tobecause they allow them to
expand the capacity of the network without laying moreexpand the capacity of the network without laying more
fiber. By using WDM andfiber. By using WDM and optical amplifiersoptical amplifiers, they can, they can
accommodate several generations of technologyaccommodate several generations of technology
development in their optical infrastructure without having todevelopment in their optical infrastructure without having to
overhaul the backbone network. Capacity of a given link canoverhaul the backbone network. Capacity of a given link can
be expanded simply by upgrading the multiplexers andbe expanded simply by upgrading the multiplexers and
demultiplexers at each end.demultiplexers at each end.
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5. DefinitionDefinition
 The concept of light tree is introduced in
a wavelength routed optical network,
which employs wavelength-division
multiplexing(WDM).
 Depending on the underlying physical
networks
1) First Generation
2) Second Generation
3) Third Generation
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6. What is a Light Tree?What is a Light Tree?
 A light tree is a point to point multipoint
all optical channel, which may span
multiple fiber links. Hence, a light tree
enables single-hop communication
between a source node and a set of
destination nodes. Thus, a light tree
based virtual topology can significantly
reduce the hop distance, thereby
increasing the network throughput.
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7. Light PathLight Path
 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.
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8. Need Of TechnologyNeed Of Technology
 Data Security
 Ease of installation
 Eliminating Spark Hazards
 High Bandwidth over Long
Distances
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9. ApplicationsApplications
 Teleconferencing
 Videoconferencing
 Internet NEWS distribution
 Internet television etc..
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10. Teleconferencing Videoconferencing
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11. Internet NEWS
distribution
Internet television
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12. FunctionalityFunctionality
 Unicast TrafficUnicast Traffic
 Broadcast TrafficBroadcast Traffic
 Multicast TrafficMulticast Traffic
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13. Unicast TrafficUnicast Traffic
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14. Unicast TrafficUnicast Traffic
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15. Unicast Traffic(contd.)Unicast Traffic(contd.)
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16. Broadcast TrafficBroadcast Traffic
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17. Multicast TrafficMulticast Traffic
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18. Combining Unicast and MulticastCombining Unicast and Multicast
TrafficTraffic
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19. Requirements
o Multicastcapable wavelength routing switches
(MWRS) at every node in the network.
o More optical amplifiers in the network. This is
because if we make n copies of an optical signal by
using one or more optical splitters, the signal power
of at least one copy will be less than or equal to 1/n
times the original signal power; thus more amplifiers
may be required to maintain the optical signal power
above a certain threshold so that the signal can be
detected at their receivers.
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20. ARCHITECTURE OF WAVELENGTH-ROUTED
OPTICAL NETWORK
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21. MULTICAST SWITCH ARCHITECTURES
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22. AdvantagesAdvantages
 Data Security
 Ease of installation
 Eliminating Spark Hazards
 High Bandwidth over Long
Distances
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23. DisadvantagesDisadvantages
 Price
 Fragility
 Opaqueness
 Requires special skills
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24. Future
o. In the future, as multicast applications become
more popular and bandwidth intensive, there
emerges a pressing need to provide multicasting
support on WANs.
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25. ConclusionConclusion
Recently, there has been a lot of interest in WDM
based fiber optic networks. In fact, there is a general
consensus that, in the near future, WANs will be
based on WDM optical networks. So far, all
architectures that have been proposed for WDM
WANs have only considered the problem of
providing unicast services. In addition to unicast
services future WDM WANs need to provide
multicast and broadcast services. A novel WDM
WAN architecture based on light trees that is
capable of supporting broadcasting and multicasting
over a wide-area network by employing a minimum
number of opto-electronic devices was discussed.
Such WDMWAN can provide a very high bandwidth
optical layer, which efficiently routes unicast,
broadcast and multicast packet-switch traffic.

26. References
 http://www.usdavis.edu
 http://en.wikipedia.org/wiki/Traffic_Light
_tree
 http://www.slideshare.net/priyakrish792/l
ight-tree-26890046
 http://www.seminarsonly.com/IT/light
%20tree.php

27. Thank YouThank You