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Switch fabric in routers requires very tight characteristics in term of packet loss, fairness in bandwidth allocation, no head-of-line blocking and low latency. Such attributes are traditionally resolved using specialized and expensive switch devices. Motivated by the emergence of IEEE Data Center Bridging, we explore the possibility of using commodity Ethernet switches to achieve scalable, flexible, and more cost efficient solutions, while still guaranteeing the switch characteristics. In this context, we propose Ethernet Congestion Control \a Prevention (ECCP), a novel concept to control and prevent congestion in switch fabrics. ECCP consists of (1) a method to estimate the available bandwidth along a given network path using a train of probes and (2) a rate control algorithm to adjust the sending rate of traffic along this path based on the estimated bandwidth. To prove ECCP and evaluate its characteristics, we present a first prototype based on the OMNEST simulator and conduct extensive experiments. Our analysis confirms that ECCP is a viable solution to (1) avoid congestion within the fabric, thus minimizing path latency and avoiding packet loss, (2) guarantee fair share of the link capacity between flows, and (3) avoid head of line blocking. |
