On Tracking the Behaviour of an Output-Queued Switch using an Input-Queued Switch with Unity Speedup
نویسندگان
چکیده
We address the problem of fair scheduling of packets in Internet routers with input-queued (IQ) switches and unity speedup. Scheduling in IQ switches is formulated as tracking the behaviour of an outputqueued (OQ) switch that provides optimal performance. We present the notion of “lag” as a performance metric that measures the difference between a packet’s departure time in an IQ switch over that 1 provided by an OQ switch. We prove that per packet mean lag is bounded for a maximum weight matching scheduling policy that uses lag values for its weights and derive a bound on the mean lag value using a Lyapunov function technique. Furthermore, we propose a simple heuristic tracking scheduling policy and evaluate its performance by simulation.
منابع مشابه
On the speedup required for combined input- and output-queued switching
Architectures based on a non-blocking fabric, such as a crosspoint switch, are attractive for use in high-speed LAN switches, IP routers, and ATM switches. These fabrics, coupled with memory bandwidth limitations, dictate that queues be placed at the input of the switch. But it is well known that input-queueing can lead to low throughput, and does not allow the control of latency through the sw...
متن کاملOptical Switching and Networking
There has been much interest to emulate the behavior of Output Queued switches. The early result of such attempts was reported by Prabhakar and McKeown using the CIOQ switches with speedup factor of 4. Subsequently, Stoica and Zhang and independently Chuang et al. showed that a speedup of 2 in conjunction with their scheduling schemes would be sufficient for CIOQ switches to emulate Output Queu...
متن کاملThroughput Analysis of the Bifurcated Input-Queued ATM Switch
In this paper there suggested is a bifurcated (or multiple) input-queued ATM switch in which a buffer for each input port is divided into multiple (m) buffer blocks, i.e., bifurcated buffers, for enhancement of the limited throughput of the ordinary input-queued switch using a single FIFO. As the contention/arbitration rule for the bifurcated input-queued switching scheme, free and restricted c...
متن کاملMatching Output Queueing with a Combined Input Output Queued Switch 1
The Internet is facing two problems simultaneously: there is a need for a faster switching/routing infrastructure, and a need to introduce guaranteed qualities of service (QoS). Each problem can be solved independently: switches and routers can be made faster by using input-queued crossbars, instead of shared memory systems; and QoS can be provided using WFQ-based packet scheduling. However, un...
متن کاملPerformance Evaluation of Combined Input Output Queued Switch with Finite Input and Output Buffers
It has recently been shown that a combined input output queued (CIOQ) switch with a speedup factor of 2 can exactly emulate an output-queued (OQ) switch [1]-[6]. In particular, the maximal matching algorithm, named Least Cushion First/Most Urgent First (LCF/MUF) algorithm presented in [6], can be executed in parallel to achieve exact emulation. However, the buffer size at every input and output...
متن کامل