Ethernet networks rely on the so-called spanning tree protocol (IEEE 802.ld) in order to break cycles, thereby avoiding the possibility of infinitely circulating packets and deadlocks This protocol impses a severe penally on the performance and scalability of large Gigabit Ethernet backbones, since it makes inefficient use of expensive fibers and may lead to bottlenecks. I n this paper, we propose a significantly more scalable cycle-breaking approach, based on the novel theory of turn-prohibition. Specifically, we intmduce, analyze and evaluate a new algorithm, called %-Based lhrn-Prohibition (TBTP). We show that this polynomial-time algorithm maintains backwardcompatibility with the IEEE 802.ld standard and never prohibits more than 11'2 of the turns in the network, for any given graph and any given spanning tree. Through extensive simulations on a variety of graph topologies, we show that it can lead to an order of magnitude improvement over the spanning tree protocol with respect to throughput and end-of-end delay metries. In addition, we prop-and evaluate beuristier to determine the replacement order of legacy switches that results in the fastest performance improvement. Index Terms-Graph Theory, System Design, Simulations. For many years, Ethernet has been the prevalent local area network (LAN) technology, offering a wide-range of services in a simple and cost-effective manner. With the standardization of Gigabit Ethernet protocols, the scope of Ethernet has widened even further [I]. A large number of corporations and service providers are now adopting Gigabit Ethernet as their backbone technology. Gigabit Ethernet backbones cope with the increasing traffic demand resulting from the deployment of high-speed LANs, home networks, Voice over IP, and highbandwidth applications. The kcy advantage of Gigabit Ethernet over alternate technologies, such as ATM, is to maintain backward-compatibility with the over one hundred millions Ethernet nodes deployed world-wide and the large number of applications running on these nodes [Z, 31. Gigabit Ethernet has the same plug-and-play functionalities as its Ethernet (IO Mbls) and Fast Ethernet (Io0 Mbh) precursors, requiring minimal manual intervention for connecting hosts to the network. In addition, Gigabit Ethernet relies on full-duplex technologies and on a flow control (hackpressure) mechanism that significantly reduce the amount of congestion E De Pelleillni 1s with the Depanment of Infomuon Engineering i t the University of Padova.
Their technique is based on turn-prohibition REF .
Scalable cycle-breaking algorithms for gigabit Ethernet backbones
IEEE INFOCOM 2004
IEEE INFOCOM 2004
Computer Science