This document discusses light trees, which are used in wavelength routed optical networks. It introduces key concepts like wavelength division multiplexing (WDM) and different transmission types (unicast, broadcast, multicast). The methodology section explains how light trees work at the optical layer, providing high bandwidth light paths between nodes. Light trees allow for efficient routing of unicast, broadcast and multicast traffic. The advantages are high bandwidth over long distances and data security, while disadvantages include higher prices and fragility. Applications include teleconferencing, videoconferencing, and internet TV.

1. LIGHT TREES
BHAVYA R WARRIER
S7 CSE
12133012
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2. CONTENTS
 Introduction
 Literature survey
 Methodology
 Results & discussions
 Conclusion
 Future scope
 References
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3. INTRODUCTION
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4.  The concept of light tree is
introduced in a wavelength
routed optical network
 Employs wavelength division
multiplexing(WDM)
 Point to point multipoint
 Enables single hop
communication
 Increases network throughput 4

5. PHYSICAL TOPOLOGIES
 First generation
• Copper based or microwave technology
• Eg: Ethernet
 Second generation
• Optical fibers for data transmission
• Switching is performed in electronic
domain Eg: FDDI
 Third generation
• Optical fibers are used
• Eg: WDM
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6. LITERATURE SURVEY
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7. TIME DIVISION MULTIPLEXING(TDM)
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8.  It is a method of transmitting
and receiving signals in a single
common path
 Multiple channels can be
combined time wise
 Transmitted over single fiber
using one wavelength
 Uses a single channel which is
accessed by many devices
 Speed is less 8

9. WAVELENGTH DIVISION
MULTIPLEXING(WDM)
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10.  Multiple time multiplexed channels
can be transmitted over a single
fiber using one wavelength
 Can deal with very high frequencies
of light
 Two types of WDM
• Coarse WDM
• Dense WDM
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11. COARSE WDM
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12. DENSE WDM
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13. METHODOLOGY
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14. WIDE AREA NETWORK(WAN)
• Network extends over a large
geographical area
• WANs are used to connect LANs
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15. LIGHT PATH
• It is an all optical channel
• Used to carry circuit switched
traffic
• It may span multiple fiber links
• Can create logical(or virtual)
neighbours out of nodes that may
be geographically far apart from
each other
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16. • The major objective of light path
communication is to reduce the
number of hops a packet has to
traverse
• Under light path communication,
the network employs an equal no.
of transmitters and receivers
• Each light path operates on a point-
to-point basis
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17. TRANSMISSION TYPES
There are three types of
transmissions used in light trees:
 Unicast traffic
 Broadcast traffic
 Multicast traffic
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18. UNICAST TRAFFIC
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19.  Unicast traffic is sent from a single
source to a single destination IP
address
 It is appropriate for many
client/server applications such as
database applications
 There is also mutistream unicast
traffic
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20. 20

21. BROADCAST TRAFFIC
 Uses a special IP address to send a
single stream of data to all of the
machines on the local network
 A broadcast address typically ends
with 255
eg 1: 192.0.2.255
eg 2: 255.255.255.255
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22. 22

23.  Broadcast transmissions are
limited to network level services
such as address resolution
 Cannot be used for applications
like video streaming
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24. MULTICAST TRAFFIC
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25.  When a data stream is sent , the
recipients of the data can decide
whether or not to receive data
 If the user wants the data, the user’s
machine receives the data else it
ignores
 That is the user can choose whether
to receive the data
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26. COMBINING UNICAST & MULTICAST
TRAFFIC
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27.  Combination is used when routers
in a network are not capable of
handling multicast traffic
 IP/TV can use unicast
transmissions to send multimedia
content across the non-multicast
enabled router
 Small casting
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28. OPTICAL LAYER
 Topology of a wavelength routing
network may be an arbitrary mesh
 Mesh consists of several fiber links
 The network provides light paths
between pairs of network nodes
 A light path is simply a high
bandwidth pipe carrying data up
to several gigabytes per second 28

29. FEATURES OF OPTICAL LAYER
• Transparency
• Wavelength reuse
• Reliability
• Virtual topology
• Circuit switching
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30. RESULTS & DISCUSSIONS
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31. ADVANTAGES OF LIGHT TREES
• Data security
• Ease of installation
• Eliminating spark hazards
• High bandwidth over long distances
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32. DISADVANTAGES OF LIGHT TREES
• Price
• Fragility
• Opaqueness
• Requires special skills
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33. APPLICATIONS OF LIGHT TREES
• Teleconferencing
• Videoconferencing
• Internet news distribution
• Internet television
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34. CONCLUSION
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35.  WDM WAN based on light trees is
capable of supporting broadcasting
and multicasting over a wide area
network
 employ a minimum number of
opto-electronic devices
 provide a very high bandwidth
optical layer
 efficiently routes unicast, broadcast
and multicast packet-switch traffic 35

36. FUTURE SCOPE
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37.  In the near future WANs will be
based on WDM optical networks
 In addition to unicast services, it
will provide broadcast and
multicast services
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38. REFERENCES
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39. [1] Laxman H. Sahasrabudhe and Biswanth
mikhergee, Light trees: Optical Multicasting For
Improved Performance in Wavelength-Routed
networks, IEEE Communication Magazine
February,1999,pp.67-73
[2] Biswanth Mukhergee, Dhritiman Banergee,
S.Ramamurthy And Amarnath Mukhergee, The
Principles for Designing a wide-area WDM
Optical Network, IEEE/ACM
Trans.Networking,VOL.4,NO.5,October1996,pp.68
4-96.
[3] Laxman H. Sahasrabudhe, Light trees: An
Optical Layer for Tomorrows IP
Networks, http://www.usdavis.edu
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40. [4] Rajiv Ramaswami and kumara N. Sivarajan
Optical Networks. Pp.333-336
[5]
www.ieng.com/univercd/cc/td/doc/product/soft
ware
[6] http://imedea.uib-
csic.es/~salvador/coms_optiques/addicional/ibm
/ch10/10-03.html
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41. THANK YOU…
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