Fast packet switches based on banyan interconnection networks and their variations are being proposed for Broadband Integrated Services Digital Network (B-ISDN). Previous analyses on buffered banyan networks mainly assume the store-and-forward operation of the switching systems. In this paper we study the effect of cut-through switching on buffered banyan networks. Two types of buffered banyan networks are considered: those with the switching elements employing input buffers and those employing output buffers. We extend the analytical method of Theimer et al. to multibuffered banyan networks, and to buffered banyan networks with output buffering in the switching elements. We present the analyses of buffered banyan networks operating under cut-through switching. The results of these analyses confirm the simulation results, originally made by Bubenik and Turner, that cut-through switching in buffered banyan networks improves both throughput and delay performances.

The effect of cut-through switching on the performance of buffered banyan networks

Approximate analysis of a discrete-time tandem network of cut-through queues with blocking and bursty traffic

The most critical issue in network virtualization is the dynamic resource allocation of the physical substrate. There is a need to monitor the running virtual routers in order to allow an adaptive change in the resource allocation. In this paper, we focus on the router data plane virtualization and we explore this issue by presenting a new dynamic allocation approach through queuing theory. We consider the problem where multiple instances of virtual routers (VRs) that have some quality of service (QoS) requirements are sharing different physical resources. We propose a novel router architecture that offers a strong isolation between concurrent VRs and provides a dynamic allocation scheme in order to guarantee the provided QoS to each of them. Our approach aims at providing a higher isolation for the concurrent virtual routers sharing the same infrastructure. We propose a dynamic Weighted Fair Queuing (WFQ) scheduler for each physical resource and an algorithm for adjusting the weight of each VR in order to reduce the delay of the packet processing and avoid the bottlenecks. We also propose an admission control mechanism that estimates the current load of the physical node and decides either to accept or reject a creation request of a new VR. Simulation results show that the proposed approach achieves good performance in terms of delay minimization inside the virtual router.

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Queuing analysis of dynamic resource allocation for virtual routers

Two acknowledgement (ACK) schemes for window flow control, full and partial ACK schemes, are investigated in conjunction with two error-checking schemes at every node or at the store-and-forward nodes only, in a quasi-cut-through switching network with noisy channel. It is shown that with respect to power and delay, the full ACK scheme performs better than the partial ACK scheme. On the other hand, in terms of throughput, the opposite holds. This reflects a tradeoff between throughput and delay in the contention system. Thus, the two ACK schemes can effectively be used to meet alternative user requirements for services in different application areas. The full ACK scheme yields better delay and throughput performance than that of conventional flow-controlled packet switching. >

Window flow control with error-checking scheme in quasi-cut-through switching network with noisy channels

In a computer communication network operating under the general cut-through switching (GCTS) mechanism, a message arriving at an intermediate network node is permitted to make a cut-through as soon as the node becomes free and provided that certain conditions are met. Delay analysis for an isolated tandem path of nodes operating in the GCTS mode has been carried out in Reference 1. Here GCTS is considered when intermediate arrivals and departures are both allowed to occur. For typical interference models, many store-and-forward switching results can be utilized under GCTS in a more general way.

http://ieeexplore.ieee.org/iel7/9754/6592770/06592780.pdf

Delay analysis for interfered paths under general cut-through switching

Cut-through switching is advantageous in that it can reduce the transmission delay compared with the conventional message or packet switching. In this paper, when the channel is noisy, we investigate various properties of M/D/1 quasi-cut-through switching including actual traffic intensity and overall network delay. In the analysis of delay resulting from retransmission of erroneous packets, we have included the average transmission time of negative acknowledgment signal and queueing time for the retransmitted packet so that the overall network delay can be obtained accurately. In addition, we have obtained distributions of the number of nodes to be traversed and the number of nodes through which packets pass by cut. According to the analysis results, the performance of cut-through switching is superior to that of conventional packet switching in most practical ranges of parameter values.

Chong Un

Papers

Performance Analysis of a Quasi-M/D/1 Cut-Through Switching Network with Noisy Channels