Application and Analysis of Multicast Blocking Modelling in Fat‐Tree Data Center Networks

Abstract

Multicast can improve network performance by eliminating unnecessary duplicated flows in the data center networks (DCNs). Thus it can significantly save network bandwidth. However, the network multicast blocking may cause the retransmission of a large number of data packets and seriously influence the traffic efficiency in data center networks, especially in the fat-tree DCNs with multirooted tree structure. In this paper, we build a multicast blocking model and apply it to solve the problem of network blocking in the fat-tree DCNs. Furthermore, we propose a novel multicast scheduling strategy. In the scheduling strategy, we select the uplink connecting to available core switch whose remaining bandwidth is close to and greater than the three times of bandwidth multicast requests so as to reduce the operation time of the proposed algorithm. Then the blocking probability of downlink in the next time-slot is calculated in multicast subnetwork by using Markov chains theory. With the obtained probability, we select the optimal downlink based on the available core switch. In addition, theoretical analysis shows that the multicast scheduling algorithm has close to zero network blocking probability as well as lower time complexity. Simulation results verify the effectiveness of our proposed multicast scheduling algorithm.

Link Load Correlation-Based Blocking Performance Analysis for Tree-Type Data Center Networks

“…With a high over-subscription ratio, the core layer links tend to be the bottleneck, and the aggregated traffic results in considerable load correlation among links in adjacent layers. The authors in [25,26] have analyzed the multi-cast blocking rates in fat-tree DCNs and proposed new multi-cast scheduling strategies to reduce blocking, based on the link load independence assumption. In [27], the blocking probabilities of different DCN architectures were compared through simulation and some congestion avoidance approaches were discussed, but a theoretical analysis was not carried out.…”