Performance analysis of virtual routing and queuing (VRQ) switch.
Date
2001
Authors
Arora, Deepali
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Abstract
A new generation asynchronous transfer mode (ATM) switch based on the principle of virtual routing and queuing (VRQ) is presented and its performance is compared with input, output, and shared buffered switches. The VRQ switch is improved since 1) it provides dedicated input queues for incoming packets destined for different outĀput ports, and 2) the output buffers store pointers to the packets, rather than the packets themselves.
Simulations are performed using traffic data generated using both Poisson and Pareto distributions. These data are used to drive the switches and to analyze their performance. The simulations are performed using C programs. The results show that while principally being an input buffered switch the performance of the VRQ switch is comparable to that of an output buffered switch. Also since VRQ is essentially an input buffered switch it is relatively easy to implement in hardware compared to the output and shared buffered switches. An improved performance and easy implemenĀtation in hardware make VRQ an ideal switch.
In regard to the effect of traffic characteristics on a switch's performance, the simulations show that switches perform better, both in terms of cell delay and cell loss, when they are driven with Poisson distributed traffic. This is expected since the Pareto distributed traffic shows more bursty behavior and exhibits larger on-periods than the Poisson traffic.
The design of the multi-ported input buffer of the VRQ switch is obtained using VHDL. This multi-ported buffer is capable of performing multiple read operations per clock cycle and can support high data rates without any speed-up requirements.