optical multicasting for interactive real-time application in sparse splitting optical networks
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DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Networked Media LaboratoryDept. of Information & Communications
Gwang-ju Institute of Science & Technology (GIST)http://netmedia.gist.ac.kr
Optical Multicasting for Interactive Real-time Application in Sparse Splitting Optical Networks
Ju-Won Park, Hyunyong Lee, and JongWon Kim 2007/ 08/ 27
APAN Network Research Workshop 2007
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Contents
Introduction Related Work Constrained Optical Multicast Routing
Problem statement The proposed light-tree construction algorithm
Experiment Results Conclusion
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Introduction
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Multicast in IP over WDM Networks IP layer multicast Multicast via WDM unicast WDM layer multicast
Multicast tree constructed by the IP layer can make copies of a data packet and transmit a copy to each of its child Require O/E/O conversion
Undesirable Inefficient Long latency
Multicast over WDM networks
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Construct a virtual topology consisting of a set of lightpaths from the multicast source to each destination (b) Using multiple unicasts Inefficient bandwidth – large multicast session
WDM switches make copies of data packets in the optical domain via light splitting (c) More desirable – transmission to different destinations can now share bandwidth on
common link Useful to support high-bandwidth multicast application such as HDTV.
WDM layer multicast potential advantages Knowledge of the physical topology – more efficient multicast routing is possible Light splitting is more efficient than copying packets Avoid the electronic processing bottleneck Support of coding format and bit-rate transparency across both unicast and multicast
Multicast over WDM networks
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Related Work
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Related Work The main mechanism of transport over optical network is light-path, a point
to point all optical channel connecting from source to destination. To incorporate optical multicasting capability, a light-tree, light-forest
concept is introduced. The problem of constructing a light-tree that spans a given source and a set of
destinations is similar to the Steiner tree problem which is known to be NP-complete
Consider several new issues and complexities for QoS provisioning of optical multicasting Sparse splitting (X. Zhang, J. Wei and C. Qiao, “Constrained Multicast Routing in WDM
Networks with Sparse Light Splitting,” in J. of Lightwave Technology, vol. 18, no. 12, December 2002.)
Power constraint (Y. Xin and G. Rouskas, “Multicast routing under optical layer constraints,” In Proc. of INFOCOM 2004)
Delay boundary (M. Chen, S.Tseng, B. Lin, “Dynamic multicast routing under delay constraints in WDM networks with heterogeneous light splitting capabilities,” in Computer Communications 29 (2006) 1492-1503)
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Constrained Optical Multicast Routing
•Problem statement•The proposed light-tree construction algorithm
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Problem Statement Sparse splitting optical network
MC (multicast capability) node MI (multicast in-capability) node
We define a delay function which assigns a nonnegative weight to each link the network
To deliver interactive real-time application via light-tree, we consider three parameters
Adequate signal quality – power constraint
End-to-end delay boundary
inter-destination delay variation boundary
),(
)(vsHT
D
),( ),(
)()(vsH usHT T
DD
),(
)(vsTH
D
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Goal Every member of session is connected Satisfy the delay and inter-destination delay variation
tolerance Balanced tree to guarantee a certain level of optical signal
power
The way Adopt hierarchical approach
Constrained Optical Multicast Routing
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Constrained Optical Multicast Routing
Make multicast backbone network Build the auxiliary MC network as referred as multicast
backbone network, Every MC node is included. Adjacent MC node is connected using logical link if there is
available wavelength on the path. If there are multiple path between MC nodes, the shortest path is selected.
The delay of logical link is equal to the delay summation of path
),(
),( )()(jiH
jiLT
MCLT
MCDHD
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Constrained Optical Multicast Routing
Physical Network(MC & MI network, G)
Multicast Backbone Networks
(MC network, G’)
Source of session 1
1
1
11
1
MC node
MI node
Source
Destination
1
1
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Constrained Optical Multicast Routing
Build the light-tree based on application requirement Source searches the MC node which is nearest from source
as referred to primary MC node. The primary MC node is unique of each session
Build the light-tree which has primary MC node as root in multicast backbone network based on constraints.
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Constrained Optical Multicast Routing
Physical Network(MC & MI network, G)
Multicast Backbone Networks
Build the light-tree based on application requirement in MC network
(MC network, G’)
Primary MC Node of session 1
Source of session 1
1
1
11
1
MC node
MI node
Source
Destination
1
1
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Constrained Optical Multicast Routing
Each destination selects a adequate MC node The MC selection by receiver is a key to construct feasible light-tree Each MI node finds the subset of on-tree MC nodes which satisfy the
delay boundary
MI node chooses the MC node which has minimum fanout in subset and then, join the light-tree by connection with selected MC node
),(
)()(),( kiLTMCLT HisH
DD
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Constrained Optical Multicast Routing
Physical Network(MC & MI network, G)
Multicast Backbone Networks
Build the light-tree based on application requirement in MC network
(MC network, G’)
Primary MC Node of session 1
Source of session 1
1
1
11
1
MC node
MI node
Source
Destination
1
1
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Completed light-tree meets the delay boundary with balanced aspect.
It does not satisfy the inter-destination delay variation boundary.
Reduce the inter-destination delay variation by swapping MI nodes
Constrained Optical Multicast Routing
),( ),(
max )()(maxvsH usHLT LT
DD
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Constrained Optical Multicast Routing
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Advantages Source need not know about the location of destinations.
Every destination need not find the minimum cost path from itself to source. It just must find the location of MC node which satisfies application requirement.
Simple construction of member-only light-tree The procedure of joining the light-tree is only performed at member.
The procedure of dynamic addition or deletion of members in a group is simple. Join: The node which wants to join in the multicast session can be
connected to its nearest MC node. Leave: The node which wants to leave can be disconnected send the
prune message to connected MC node.
Constrained Optical Multicast Routing
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Experiment Results
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Experiment Results
The number of MI nodes
0 20 40 60 80 100 120 140
Inte
r-de
stin
atio
n de
lay
varia
tion
(ms)
40
60
80
100
120
140
160
180
200
220
240
Shortest path approachBalanced approach (LT0)Proposed approach
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Number of MI nodes
0 20 40 60 80 100 120 140
Max
imum
Spl
it R
atio
0
100
200
300
400
500Shortest path approachBalanced approach, proposed approach
Experiment Results
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Conclusion
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Conclusion & Future Work To support multicast in optical network
a balanced light-tree to guarantee signal quality Delay and inter-destination delay variation along all source-destination
paths in the tree should be bounded in sparse splitting optical network. The proposed algorithm is heuristic approach to obtain the
feasible light-tree
Wavelength assignment algorithm should be explored in future research. Minimize wavelength cost
DEPT. OF INFO. & COMM., GISTNetworked Media Lab.
Q&A
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