Birkhoff-von Neumann switch with deflection based load balancing

Abstract

-Load balanced Birkhoff-von Neumann (LBBvN) packet switches have low hardware complexity while achieving high performance. We propose a novel LB-BvN based switch that achieves 100% throughput for any admissible traffic scenario. The proposed switch uses the deflection mechanism to decrease overall hardware complexity of the switch. The delay and buffer bounds of the proposed switch are derived and analyzed using the network calculus theory. The proposed switch is compared to other LBBvN based solutions.Keywords -Birkhoff-von Neumann switches, load balancing, network calculus, packet switching.I. INTRODUCTION HE network operators are installing higher and higher link capacities in order to support increasing traffic demands. Routers and switches must implement highly efficient packet switches to support these continuously increasing link capacities. It is imperative that the packet switch achieves high performances under any admissible traffic scenario. Also, the packet switch needs to be scalable, both in terms of supported number of ports and supported link capacities.The Birkhoff-von Neumann (BvN) based switches are very popular because they avoid the problem of calculating the packet switch configuration on the fly like input queued switches. BvN switch uses the capacity decomposition approach [1] - [2]. Based on the traffic demands, a set of packet switch configurations is calculated. The calculated set of configurations is periodically repeated, thus, the problem of calculations in the real time is avoided (O(1) complexity to configure the packet switch). But, as the traffic demands dynamically change, the set of packet switch configurations should be frequently recalculated. The computation complexity is very high -O (N 4.5 ). Also, it is not easy to perform real time measurements of the traffic fluctuation.Load-balanced two stage BvN (LB-BvN) switch was proposed to couple with these problems [3] - [4]. The packet switch in each stage periodically repeats N configurations. There are no calculations of the packet switch configuration. The first stage balances the incoming traffic to buffers that are placed between the first and second stage. The first stage tries to create the uniformly distributed traffic for the second stage to avoid the need for the recalculations of the packet switch configurations. The load-balanced BvN switch achieves high performances for a broad class of traffic scenarios. However, in some traffic scenarios the switch throughput can be severely decreased. Also, out-of-order problem occurs because the packets of the same flow go through different paths in the LB-BvN switch. The resequencing buffer is used at the output port to restore the original packet order. In [4], the authors proposed the load balancing of the packets according to flows not the arrival times to support the multicast flows and they placed the jitter control in front of the VOQs of the second stage. The role of the jitter control is to delay the packets so it seems that the packets enter the second s...