1,721,038 research outputs found
ExpressMAN: Exploiting Traffic Locality in Expressnet
No full textExpressMAN is a metropolitan area network architecture which connects users grouped in different clusters. It retains all the positive features of LAN's, but in addition, allows for parallel transmission of local traffic. The overall network structure is halfway between a linear bus and a two-level hierarchical structure in which several subnetworks are connected by a backbone network. However, it does not need complex routing facilities like bridges. Based on the Expressnet access mechanism, it can be dynamically configured either as a unique bus or as several different local buses which allow the circulation of long distance and local trains, respectively. Routing is performed by the transmitting stations choosing the correct train. Local communications can take the bandwidth not used by long distance trains, and thus increase bandwidth efficiency by means of parallel transmissions. In this paper, the performance of ExpressMAN is evaluated and compared to that achieved by the aforementioned two-level structure based on Express networks. Although the Expressnet mechanism has been chosen as the simplest and most efficient mechanism available for LAN's the principle underlying ExpressMAN could be applied to other token schemes such as the token ring
A collision resolution algorithm for random-access channels with echo
No full textn this paper random access algorithms for packet broadcast channels are considered. It is shown that utilizing channels with a central repeater as for instance a satellite channel more information is available to resolve conflicts than that utilized ..
The Effect of High-Level Acknowledgment Traffic on the Throughput of ALOHA Channels
No full textThe behavior of the throughput of an ALOHA channel is investigated, taking into account the effect of acknowledgment traffic when the acknowledgment mechanism is provided by high-level protocols. It is shown that the use of redundant ACK packets slightly increases the channel throughput
On the Throughput of an ALOHA Channel with Variable Length Packets
No full textIn this paper we give a new simple expression for the probability of successful transmission on an infinite population ALOHA channel with variable length packets. Expressions for the throughput and the probability density of the packet length on the channel are derived in a straightforward way along with the best and the worst length densities
HR4-Net: A Hierarchical Random-Routing Reliable and Reconfigurable Network bfor Metropolitan Area
No full textOn the Throughput of an ALOHA Channel with Variable Length Packets
No full textIn this paper we give a new simple expression for the probability of successful transmission on an infinite population ALOHA channel with variable length packets. Expressions for the throughput and the probability density of the packet length on the channel are derived in a straightforward way along with the best and the worst length densities
On the design of Optical Deflection - Routing Networks
No full textDeflection routing plays a prominent role in many optical network architectures, because it can be implemented with modest packet-buffering requirements. From the practical perspective, however, the implementation of deflection routing, which is normally based on global time slotting, might pose challenges. The authors develop approaches to the implementation of both slotted and unslotted deflection-routing optical networks. They analyse important tradeoffs that are inherent to the design of optical deflection-routing networks and compare the performance of slotted and unslotted networks. Under a reasonable set of assumptions about optical technology, the results suggest that the unslotted link protocol should be the preferred approach to building the optical deflection-routing networ
Metodo di Allocazione di Banda, di Tipo Distribuito, in una Rete Passiva con un Accesso Multiplo CSMA/CD
No full textMetodo di allocazione di una banda prefissata tra una pluralità di terminali (ONU) connessi ad un concentratore (HUB) in una rete con un accesso multiplo CSMA/CD caratterizzato dal fatto di comprendere le seguenti fasi: ogni terminale (ONU) presente in rete, ad intervalli di tempo prefissati, individua i terminali (ONU) attivi nel precedente intervallo di tempo; ogni terminale (ONU) attivo determina un valore di banda ad esso disponibile, mediante un metodo prefissato; ogni terminale (ONU) attivo si alloca detto valore di banda ad esso disponibile. In una prima forma di realizzazione si verifica quali ONU erano attive nel precedente intervallo di tempo, mediante l’ascolto del traffico upstream riflesso indietro a tutte le ONU dal HUB passivo. La banda in upstream è distribuita tra tutte le ONU che erano attive nel precedente intervallo di tempo proporzionalmente al loro peso. In una seconda forma di realizzazione, si tiene conto dell’ammontare del traffico trasmesso dalle ONU attive nel precedente intervallo di tempo nel processo di allocazione della banda
Expressnet: A High-Performance Integrated-Services Local Area Network
No full textExpressnet is a local area communication network comprising an inbound channel and an outbound channel to which the stations are connected. Stations transmit on the outbound channel and receive on the inbound channel. The inbound channel is connected to the outbound channel so that all signals transmitted on the outbound channel are duplicated on the inbound channel, thus achieving broadcast communication among the stations. In order to transmit on the bus, the stations utilize a distributed access protocol which achieves a conflict-free round-robin scheduling. This protocol is more efficient than existing round-robin Schemes as the time required to switch control from one active user to the next in a round is minimized (on the order of a carrier detection time), and is independent of the end-to-end network propagation delay. This improvement is particularly significant when the channel data rate is so high, or the end-to-end propagation delay is so large, Or the packet size is so small as to render the end-to-end propagation delay a significant fraction of, or larger than, the transmission time of a packet. Moreover, some features of Expressnet make it particularly suitable for voice applications. In view of integrating voice and data, a simple access protocol is described which meets the bandwidth requirement and maximum packet delay constraint for voice communication at all times, while guaranteeing a minimum bandwidth requirement for data traffic. Finally, it is noted that the voice/data access protocol constitutes a highly adaptive allocation scheme of channel bandwidth, which allows data users to recover the bandwidth unused by the voice application. It can be easily extended to accommodate any number of applications, each with its specific requirements
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