7 research outputs found
Recommended from our members
Performance analysis of a broadcast star local area network with collision avoidance. Part 1, Infinite station population model
Packet collisions and their resolution create a performance bottleneck in random access LANs. As a solution to this problem, a broadcast star network with collision avoidance has been proposed and studied in [3 - 17]. In a broadcast star network, collisions of simultaneously transmitted packets are avoided by means of hardware called a collision avoidance switch. While the channel is being used by one station, the collision avoidance switch blocks other stations from using it. This network implements random access protocols without the penalty of collisions among packets and combines the benefits of random access (low delay when traffic is light; simple, distributed, and therefore robust protocols) with excellent network utilization.In this paper, we analyze the performance of a broadcast star network, assuming synchronous operation of a network. In synchronous operation, the channel time is slotted, and stations transmit only at the beginning of a slot. The number of stations on a network is assumed to be infinite, and packets arrive at stations according to a Poisson process. An exact analysis is developed, and the distribution for the transmission delays is obtained. It is also shown through simulations that a broadcast star operating under synchronous mode yields better performance than that operating under asynchronous mode, where transmissions of packets are not confined to the beginning of slots, and stations start transmission any time
Recommended from our members
Design implementation and measurement of a collision avoidance multiple broadcast tree network
Packet collisions and their resolution create a performance bottleneck in random access LANs. Collision avoidance switches are a hardware solution to this problem [1, 2]. Collision avoidance switches allow the implementation of random access protocols without the penalty of collisions among packets.In this paper, we describe a design and implementation of a local area network architecture based on collision avoidance, called the Collision Avoidance Multiple Broadcast (CAMB) tree network. Our implementation follows the protocol layering architecture of the IEEE 802 local area networks, and includes CAMB tree switches, station/network interface boards, and support of transport protocols. We also present the performance measurements of our experimental CAMB tree network
Recommended from our members
A VLSI implementation of the collision avoidance switch protocol for CAMB tree LANs
To solve a performance bottle neck in random access LANs due to packet collisions and their resolution, collision avoidance switches are introduced. These switches allow random access protocols to achieve high performance by resolving collisions among packets. A conventional hardware implementation of these switches is the use of TTL chips. In this implementation; a handful of TTL chips are required to forma single switch (e.g., 18 TTL chips are needed for an implementation of the CAMB switch [7]). Thus, implementation of a complete network, which requires several of these switches, could very well result in a large and complex hardware system.Today's modern chip technology allows us to pack large quantity of logic in a single chip. By transferring the conventional implementation of the collision avoidance switches into a VLSI chip, the complexity of the resultant hardware is greatly reduced, not to mention the improvement in hardware performance and ease of packaging.This report provides an overall study of the collision avoidance protocols for the tree LANs with emphasis on the implementation of collision avoidance switches. Hardware implementations of sorne of these switches are discussed. And a VLSI implementation of the CAMB switch protocol is introduced
Recommended from our members
Collision Avoidance Tree networks
The Collision Avoidance Tree is a new local area network based on a hardware device called collision avoidance switch, which arbitrates random access to a shared communications channel. Collision Avoidance Tree combines the benefits of random access (low delay when traffic is light; simple, distributed, and therefore robust, protocols) with concurrency of transmission, excellent network utilization and suitability for the domain of high-speed, optical networking.The Collision Avoidance Tree is classified in two classes: the Collision Avoidance Single Broadcast (CASB) Tree and the Collision Avoidance Multiple Broadcast (CAMB) Tree. The CASB Tree allows only a single transmission on the network at a given time, while the CAMB Tree is more general and allows concurrent transmissions on the network.This paper describes network architectures (e.g., station and switch protocols) and designs and implementations of the CASB and CAMB Trees. Performance results derived from analyses, simulations, measurements of experimental networks are also presented
Recommended from our members
Performance analysis of a broadcast star local area network with collision avoidance. Part 2, Finite station population model
In order to overcome the performance bottleneck due to collisions and their resolution in random access LANs, a new network architecture called a broadcast star network with collision avoidance has been proposed and studied by many researchers [2 - 15]. The performance of a broadcast star network is also studied in a companion paper [11], assuming an infinite station population and synchronous operation of the network.In this paper, we analyze the performance of a broadcast star network assuming a finite number of stations, and we obtain the throughput and the distribution of transmission delays. An exact analysis is presented first. However, this analysis is computationally practical for networks with a small number of stations only. Therefore, an approximate analysis is also presented for a network having a large number of stations. The accuracy of our approximation is examined through simulations
Recommended from our members
Performance analysis of a broadcast star local area network with collision avoidance. Part 1, Infinite station population model
Packet collisions and their resolution create a performance bottleneck in random access LANs. As a solution to this problem, a broadcast star network with collision avoidance has been proposed and studied in [3 - 17]. In a broadcast star network, collisions of simultaneously transmitted packets are avoided by means of hardware called a collision avoidance switch. While the channel is being used by one station, the collision avoidance switch blocks other stations from using it. This network implements random access protocols without the penalty of collisions among packets and combines the benefits of random access (low delay when traffic is light; simple, distributed, and therefore robust protocols) with excellent network utilization.In this paper, we analyze the performance of a broadcast star network, assuming synchronous operation of a network. In synchronous operation, the channel time is slotted, and stations transmit only at the beginning of a slot. The number of stations on a network is assumed to be infinite, and packets arrive at stations according to a Poisson process. An exact analysis is developed, and the distribution for the transmission delays is obtained. It is also shown through simulations that a broadcast star operating under synchronous mode yields better performance than that operating under asynchronous mode, where transmissions of packets are not confined to the beginning of slots, and stations start transmission any time