A novel WDM architecture based light tree are capable of supporting broadcasting and multicasting.Employing the minimum number of optoelectronic devices, It can provide a very high bandwidth optical layer which efficiently routes unicast, broadcast and multicast packet switch traffic.If we employ a set of light trees, then significant savings can be achieved in terms of number optoelectronic devices in the network.
2. LIGHT TREES
SEMINAR COORDINATORS
Mr. UNNIKRISHANAN.P
Mrs. CHAITHANYA RAJ
PRESENTED BY
GAYATHRI DEVI.K.V
S7 ECE
ROLL NO : 22
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3. CONTENTS
INTRODUCTION
BLOCK DIAGRAM
TYPES OF WDM
COMPARISON BETWEEN CWDM AND DWDM
LIGHT PATH
LIGHT TREE
ARCHITECTURE OF WAVELENGTH ROUTED OPTICAL NETWORKS
MUTICAST SWTICHED ARCHITECTURES
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4. CONTINUATION…
OPTICAL LAYER
TRAFFIC MECHANISMS
LIGHT TREE PROBLEM FORMULATIONS
ADVANTAGES
DISADVANTAGES
APPLICATIONS
CONCLUSION
REFERENCE
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5. INTRODUCTION
In near future wide area networks(WAN) will be based on Wavelength Division
Multiplexed(WDM) optical networks
Physical topology networks can be classified into three generations
1st generation: Networks employs copper-based or microwave technology
E.g. : Ethernet
2nd generation: Networks use optical fibres for data transmission but switching is
performed in electronic domain
E.g.: FDDI
3rd generation :Networks with both data transmission and switching is performed in
optical domain
E.g.: WDM14 July 2017 DEPT OF ECE 5
11. LIGHT PATH
Optical channel which may be used to carry circuit switched traffic
May span multiple fibre links
Can create logical(or virtual) neighbours
Light path carries direct traffic between nodes it interconnects
Major objective of light path communication is to reduce the number of hops
Under light path communication the network employs an equal number of
transmitters and receiver because light path operates on point to point basis
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12. LIGHT TREE
Light tree is a point to multipoint all optical channel which may span multiple
fibre links
Enables single-hop communication between a source node and a set of destination
nodes
Light tree based network topology can reduce the hop distance, thereby increasing
the network through put
In general light tree is a point to multipoint extension of light path
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14. LIGHT TREE EXAMPLE
Architecture of wavelength-routed
network and layered graph
representation
(a) represents a light path on
wavelength λ1 from node A to node
C, and a light path on wavelength
λ2 from node A to node F
(b) represents layered-graph model
with three wavelength layers
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15. CONTINUATION…
WDM network requires efficient delivery of broadcast and multicast
applications
Modelled as a layered graph which represents a wavelength
Each physical fibre has a corresponding link on each layer
Switching state of each wavelength-routing switch(WRS) is managed by
controller
Employ tuneable lasers and filters at access nodes and optical/electronic
switches at routing nodes
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16. MULTICAST SWITCHED
ARCHITECTURES
LINEAR DIVIDER COMBINER(LDC)
Two input fibres(Pi’s) and two output
fibres (Po’s) two dividers and two
combiners
Power of one output signal is less than or
equal to 1/n of input signal
Acts as generalised optical switch with the
added function of multicasting and
broadcasting
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17. MWRS BASED ON A SPLITTER
BANK
Optical splitter is a passive device
Splits input signal to multiple identical
output signals
Support four wavelengths on each fibre
link
Information on each incoming link is first
demultiplexed into separate wavelengths
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18. CONTINUATION ……
Separate signals each on separate wavelengths are switched by the optical switch
(OSW)
Signals that do not need duplication are sent directly to output ports
Signals that need to be duplicated are sent to a port connected to a splitter bank.
Provide optical signal amplification, wavelength conversion and signal
regeneration for multicast as well as unicast applications
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19. MWRS BASED ON A
“DROP AND CONTINUE” SWITCH
Light path can be terminated at node
Identical copy of light path allowed to continue in another node
Constructed a chain of node connected by a drop and continue light path
All nodes on the chain will receive transmissions on a drop and continue light
path where light is dropped
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20. OPTICAL LAYER
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Optical layer provides light paths to the higher layers
Have the following features
• Transparency
• Reliability
• Wavelength reuse
• Virtual topological network
• Circuit switching
21. TRAFFIC MECHANISMS
Unicast traffic
Broadcast traffic
Multicast traffic
UNICAST TRAFFIC
Sent from a single source to single destination IP address
Used by IP/TV on demand
Each user request program at different time
Limited by band width
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23. BROADCAST TRAFFIC
Uses a special IP address to sends data,
sends single stream data to all machines
in local network
Broadcast address typically ends in 255
e.g.: 192.0.2.255
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24. MULTICAST TRAFFIC
Used by IP/TV scheduled programs
Reach unlimited number of users
No overloading of network
User can decide to receive or ignore
data
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25. LIGHT TREE PROBLEM
FORMULATIONS
Here a problem formulation of a light tree based on unicast traffic it requires following inputs:
Physical topology Gp=(V,Ep) consisting of a weighted undirected graph
Where,
V is the set of network nodes
Ep is the set of links connecting nodes
Undirected means that each link in the physical topology is bi-directional
Number of wavelength channels carried by each fibre =W
NxN traffic matrix, where N is the number of network nodes
(i,j)th element is the average rate of traffic flow from node i to node j
Number of wavelength tuneable lasers as (Ti) and wavelength tuneable filters as (Ri) at each node
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26. ADVANTAGES
Data security
Ease of installation
Eliminating spark hazards
High Bandwidth(up to 50 terabits per second) over long distances
Significantly reduce hop distance
Minimize total number of transceivers in a network
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27. DISADVANTAGES
Difficulties arising from limited number of wavelengths
Requires special skills
Fragile
Opaqueness
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29. FUTURE ENHANCEMENT
Wavelength cost could be minimized
Wavelength assignment algorithm should be explored in future
research
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30. CONCLUSION
Novel WDM architecture based light tree are capable of supporting broadcasting
and multicasting
Employing minimum number of optoelectronic devices
Can provide very high bandwidth optical layer which efficiently routes unicast ,
broadcast and multicast packet switch traffic
If we employ a set of light trees, then significant savings can be achieved in terms
of number optoelectronic devices in the network
14 July 2017 DEPT OF ECE
30
31. REFERENCE
Laxman H. Sahasrabudhe and Biswanth Mukherjee, Light trees :Optical
Multicasting For Improved Performance in Wavelength-Routed networks,IEEE
Communication Magazine. February pp.67-73
Biswanth Mukherjee, Dhritiman Banerjee, S. Ramamurthy And Amaranth
Mukherjee, The Principles for Designing a wide-area WDM Optical Network,
IEEE/ACM
Laxman H. Sahasrabudhe, Light trees: An Optical Layer for Tomorrow’s IP
Networks, Rajiv Ram swami and kumara N. Sivarajan Optical Networks. Pp.333-
336.
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