Optical Multicasting for Interactive Real-time Application in Sparse Splitting Optical Networks

1. APAN Network Research Workshop 2007 Optical Multicasting for Interactive Real-time Application in Sparse Splitting Optical Networks Ju-Won Park, Hyunyong Lee, and JongWon Kim 2007/ 08/ 27

2. Contents • Introduction • Related Work • Constrained Optical Multicast Routing • Problem statement • The proposed light-tree construction algorithm • Experiment Results • Conclusion

3. Introduction

4. Multicast over WDM networks • 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

5. Multicast over WDM networks • 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

6. Related Work

7. 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-forestconcept 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)

8. Constrained Optical Multicast Routing • Problem statement • The proposed light-tree construction algorithm

9. 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

10. Constrained Optical Multicast Routing • 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

11. 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

12. Constrained Optical Multicast Routing

13. 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.

14. Constrained Optical Multicast Routing

15. 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

16. Constrained Optical Multicast Routing

17. Constrained Optical Multicast Routing • 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

18. Constrained Optical Multicast Routing

19. Constrained Optical Multicast Routing • 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.

20. Experiment Results

21. Experiment Results

22. Experiment Results

23. Conclusion

24. 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

25. Q&A