State Scalability Problem Research Articles

An ant colony optimisation algorithm for aggregated multicast based on minimum grouping model

SUMMARYThe tree‐based delivery structure of the traditional Internet protocol multicast requires each on‐tree router to maintain a forwarding state for a group. This leads to a state scalability problem when large numbers of concurrent groups exist in a network. To address this state scalability problem, a novel scheme called aggregated multicast has recently been proposed, in which multiple groups are forced to share one delivery tree. In this paper, we define the aggregated multicast problem based on the minimum grouping model, and propose an ant colony optimisation algorithm. The relative fullness of the tree is defined according to the characteristics of the minimum grouping problem and is introduced as an important component in identifying the aggregation fitness function between two multicast groups. New pheromone update rules are designed based on the aggregation fitness function. To improve the convergence time of the algorithm, we use the changes (brought by each group) in the relative fullness of the current tree as the selection heuristic information. The impact of the relative fullness of the tree is analysed using the hypothesis test, and simulation results indicate that introducing relative fullness to the fitness function can significantly improve the optimisation performance of the algorithm. Compared with other heuristic algorithms, our algorithm has better optimisation performance and is more suitable for scenarios with larger bandwidth waste rates. Copyright © 2011 John Wiley & Sons, Ltd.

An Approach to Improve the State Scalability of Source Specific Multicast

Problem statement: Source Specific Multicast (SSM) is an acceptable solution for current multicast applications; since the driving applications to date are one to many, including Internet TV, distance learning, file distribution and streaming media. Approach: It was useful for billing, address allocation and security. SSM still had serious state scalability problem when there were a large number of simultaneous on-going multicast groups in the network. Results: In this study, a scheme had been devised to improve the state scalability of source specific multicast. The scheme consisted of two stages: Conclusion/Recommendations: The first stage was to cluster the receivers based on their IP addresses and the second stage was to reduce the multicast state at routers. In order to prove the correctness of the proposed scheme, it had been applied to multicast trees built by other researchers. The results of the comparison approved our statement.

A Scalable Overlay Multicast Architecture for Large-Scale Applications

In this paper, we propose a two-tier overlay multicast architecture (TOMA) to provide scalable and efficient multicast support for various group communication applications. In TOMA, multicast service overlay network (MSON) is advocated as the backbone service domain, while end users in access domains form a number of small clusters, in which an application-layer multicast protocol is used for the communication between the clustered end users. TOMA is able to provide efficient resource utilization with less control overhead, especially for large-scale applications. It also alleviates the state scalability problem and simplifies multicast tree construction and maintenance when there are large numbers of groups in the network. To help MSON providers efficiently plan backbone service overlay, we suggest several provisioning algorithms to locate proxies, select overlay links, and allocate link bandwidth. Extensive simulation studies demonstrate the promising performance of TOMA

Tackling group-to-tree matching in large scale group communications

As a mechanism to efficiently support group communications, multicasting, faces a serious state scalability problem when there are large numbers of groups in the network. Recently, a novel solution called Aggregated Multicast has been proposed, in which multiple groups can share one delivery tree. A key problem in Aggregated Multicast is group-to-tree matching (i.e., assigning groups to proper trees). In this paper, we formally define this problem, and formulate two versions of the problem: static and dynamic. We analyze the static version and prove that it is NP-complete. To tackle this hard problem, we propose three algorithms: one optimal (using Linear Integer Programming, or ILP), one near-optimal (using Greedy method), and one Pseudo-Dynamic algorithm. For the dynamic version, we present a generic dynamic on-line algorithm. Simulation study has been conducted to evaluate the performance of the algorithms. Our results show that: (1) for the static problem, the Greedy algorithm is a feasible solution and its performance is very close to the optimal ILP solution, while the Pseudo-Dynamic algorithm is a good heuristic for many cases where Greedy does not work well; (2) for the dynamic problem, the generic dynamic on-line algorithm is a very practical solution with promising performance and reasonable computation requirement.

AQoSM: Scalable QoS multicast provisioning in Diff-Serv networks

The deployment of IP multicast support is impeded by several factors among which are the state scalability problem, the cumbersome management and routing, and the difficulty of supporting QoS. In this paper, we propose an architecture, called Aggregated QoS Multicast (AQoSM), to provide scalable and efficient QoS multicast in Diff-Serv networks. The key idea of AQoSM is to separate the concept of groups from the concept of distribution tree by “mapping” many groups to one distribution tree. In this way, multicast groups can now be routed and rerouted very quickly by assigning different labels (e.g., tree IDs) to the packets. Therefore, we can have load-balancing and dynamic rerouting to meet QoS requirements. In addition, the aggregation of groups on fewer trees leads to routing state reduction and less tree management overhead. Thus, AQoSM enables multicast to be seamlessly integrated into Diff-Serv without violating the design principle of Diff-Serv of keeping network core “QoS stateless” and without sacrificing the efficiency of multicast. Finally, efficient resource utilization and strong QoS support can be achieved through statistical multiplexing at the level of aggregated trees. We design a detailed MPLS-based AQoSM protocol with efficient admission control and MPLS multicast tree management. By simulation studies, we show that our protocol achieves significant multicast state reduction (up to 82%) and tree maintenance overhead reduction (up to 86%) with modest (12%) bandwidth overhead. It also reduces the blocking ratio of user requests with strong QoS requirements due to its load balancing and statistical multiplexing capabilities.

Aggregated Multicast ? A Comparative Study

Though IP multicast is resource efficient in delivering data to a group of members simultaneously, it suffers from scalability problem with the number of concurrently active multicast groups because it requires a router to keep forwarding state for every multicast tree passing through it. To solve this state scalability problem, we proposed a scheme, called aggregated multicast. The key idea is that multiple groups are forced to share a single delivery tree. In our earlier work, we introduced the basic concept of aggregated multicast and presented some initial results to show that multicast state can be reduced. In this paper, we develop a more quantitative assessment of the cost/benefit trade-offs. We propose an algorithm to assign multicast groups to delivery trees with controllable cost and introduce metrics to measure multicast state and tree management overhead for multicast schemes. We then compare aggregated multicast with conventional multicast schemes, such as source specific tree scheme and shared tree scheme. Our extensive simulations show that aggregated multicast can achieve significant routing state and tree management overhead reduction while containing the expense of extra resources (bandwidth waste and tunnelling overhead). We conclude that aggregated multicast is a very cost-effective and promising direction for scalable transit domain multicast provisioning.

A Scalable Model for Interbandwidth Broker Resource Reservation and Provisioning

As the Internet evolves into global communication and commercial infrastructure, the need for quality-of-services (QoSs) in the Internet becomes more and more important. With a bandwidth broker (BB) support in each administrative domain, differentiated services (Diffserv) is seen as a key technology for achieving QoS guarantees in a scalable, efficient, and deployable manner in the Internet. In this paper, we present a scalable model for inter-BB resource reservation and provisioning. Our BB uses centralized network state maintenance and pipe-based intradomain resource management schemes that significantly reduce admission control time and minimize scalability problems present in prior research. For inter-BB communication, we design and implement a BB resource reservation and provisioning protocol (BBRP). BBRP performs destination-based aggregated resource reservation based on bilateral service level agreements (SLAs) between peer-BBs. BBRP significantly reduces the BB and border routers state scalability problem by maintaining reservation state based only on destination region. It minimizes inter-BB signaling scalability by using aggregated type resource reservation and provisioning. Both analytical and experimental results verify the BBRP achievements.