Multicast Overlay for High-Bandwidth Applications Over Optical WDM Networks

Abstract

Multicast communication in wavelength division multiplexed (WDM) networks is traditionally supported by the assumption that the optical crossconnects are multicast capable, i.e., they are capable of switching an incoming signal to more than one output interface. A naïve method of supporting this functionality in a multicast-incapable (MI) environment is by creating a virtual topology consisting of lightpaths from the multicast source to each destination of the multicast session. For large sets of multicast requests, however, the network bandwidth consumed by such a scheme may become unacceptable due to the unicasting nature of the lightpaths. We refer to this method as achieving multicast via WDM unicast (MVWU). To support users' multicast requests (from higher electronic layers) in MI networks, we propose two overlay solutions: drop at member node (DMN) and drop at any node (DAN). In these solutions, we achieve multicasting by creating a set of lightpath routes (possibly multiple hops) in the overlay layer from the source node of a request to each destination member. In the DMN case, we allow a lightpath route to originate/terminate only at source and destination members of a request, whereas in the DAN model we impose no such restrictions. We first consider a static traffic model, wherein the set of multicast requests is known ahead of time, and present integer linear programs (ILPs) to solve these problems (MVWU, DMN, and DAN) with the goal of minimizing the total number of wavelengths required to service the set. We also present an efficient heuristic and compare its performance to the ILP for a small network, and run simulations over real-world, large-scale networks. Moreover, we present lower bounds to calculate the minimum number of wavelengths required by the DMN and DAN models. Finally, we evaluate the performance of the heuristic (minimization of the number of wavelengths) under a dynamic traffic scenario and also evaluate the blocking performance for a fixed number of wavelengths.

Static protection against single multicast resource failure

“…The Multicast Destination Failure Protection ILP formulated below is based in part on the Drop at Member Node (DMN) multicast overlay ILP, presented in [14]. The DMN approach to establishing multicast circuits in optical networks efficiently establishes a logical overlay over the underlying physical network.…”

On the Spectrum-Efficient Overlay Multicast in Elastic Optical Networks Built with Multicast-Incapable Switches

“…Two core network topologies are tested, i.e., the 14-node NSFNET and the 28-node US Backbone [11]. To generate the multicast requests, we set the average size of the multicast groups (i.e., |D i |) as 4, determine the member nodes with the assumption that each node in the topology has equal probability to be included, and then select the source node randomly from the 6 calculate the shortest-path from V in to V out ; 7 store the path in sp; 8 insert sp into T i ; 9 store the end node of sp as d i,j ; member nodes. The size of a multicast group can vary from 1 (unicast) to |V | − 1 (broadcast).…”

“…To this end, it would be interesting to investigate overlay multicast (OL-M) in EONs built with multicast-incapable (MI) switches. For OL-M, a logic light-tree is constructed for a multicast request and multiple unicast lightpaths are then set up to actually carry it [8]. Therefore, multicast is accomplished over the MI infrastructure, and cost-effective network planning and provisioning are feasible, especially when multicast traffic is not dominant.…”

Multicast service-oriented Virtual Network mapping over Elastic Optical Networks

“…Recently, some multicast tree routing issues were investigated for networks with fixed multicasting source and destination nodes [6][7][8][9][10][11][12][13]. The authors in [6] studied the online routing of bandwidth-guaranteed multicasts in traditional IP networks which can be applied into provisioning bandwidth-guaranteed virtual private network (VPN) services under the "hose" service model.…”

“…The authors in [8] studied the joint optimization problem of multicast routing and sparse splitting in WDM networks wherein some switches are incapable of splitting light. The work in [9] focused on supporting multicast routing from electronic layers in Multicast Incapable (MI) WDM networks. The work in [11][12][13] given.…”