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Virtual Networking
Published in Dijiang Huang, Ankur Chowdhary, Sandeep Pisharody, Software-Defined Networking and Security, 2018
Dijiang Huang, Ankur Chowdhary, Sandeep Pisharody
The challenge here is how to differentiate between a switch and a bridge? Before describing the difference, we need to first explain how Ethernet works, in which switches and bridges are designed to support. Ethernet was originally an everyone sees all traffic protocol running over a LAN. When a node is using the network, others need to wait until the next chance that no one uses the network. If two nodes try to use the network at the same time, then collision occurs, and then both nodes need to wait a random amount of time before attempting to use the network again. This illustrates that Ethernet is designed for a shared communication media (or bus), and each Ethernet is a collision domainCollision Domain or what is called broadcast domainBroadcast Domain. Traditionally, a bridge usually is explained as a 2-port device to connect two LANs, where we consider each LAN as a shared bus or collision domain. Using a bridge, a large collision domain can be separated into two smaller collision domains, and thus reducing the chance of collisions for each port. From this view, we can simply illustrate that an Ethernet switch is a multi-port Ethernet bridge, i.e., a switch is simply a bridge with lots of ports. Thus, we can simply view a switch is the same device as a multi-port bridge. A switch will increase the number of collision domains on a LAN, where each port will be a collision domain; however, the size of these domains will be reduced. For a full-duplex switch, technically, the switch can remove collisions totally.
Data Link Layer
Published in Mário Marques da Silva, Cable and Wireless Networks, 2018
Similar to a bridge, a switch performs the segmentation of a network into smaller collision domain segments. In fact, in case each segment connects a single host, the collision domains are avoided, and consequently, the CSMA-CD mechanism described below is not applicable. However, while the bridge is typically equipped with only two interfaces (which can be of different MAC sublayer types), the number of interfaces of the switch is typically high. Moreover, these interfaces are typically of the same type (e.g., IEEE 802.3/Ethernet protocol). Nowadays, the switch tends to be the central node of the network, instead of the previously used hub. Moreover, the bridge has been replaced by the switch.
Ad Hoc Networks
Published in Jerry C. Whitaker, Microelectronics, 2018
Michel D. Yacoub, Paulo Cardieri, Élvio João Leonardo, Álvaro Augusto Machado Medeiros
A particular case of ad-hoc network, which is drawing significant attention, is the wireless mesh network (WMN). The main characteristic that differentiates a WMN from others ad-hoc networks is the traffic pattern: practically, all traffic is either to or from a node (gateway) that is connected to other networks (e.g. Internet). Consequently, the gateway plays a decisive role in the WMN: the greater the number of gateways the greater the capacity of this network as well as its reliability. Jun and Sichitiu (Jun, (Oct) 2003) analyze the capacity of WMNs with stationary nodes. Their work shows that the capacity of WMNs is extremely dependent on the following aspects: Relayed traffic and fairness—Each node in a WMN must transmit relayed traffic as well as its own. Thus, there is an inevitable contention between its own traffic and relayed traffic. In practice, as the offered load at each node increases, the nodes closest to the gateway tends to consume a larger bandwidth, even for a fair MAC layer protocol. The absolute fairness must be forced according to the offered load.Nominal capacity of MAC layer (B)—It is defined as the maximum achievable throughput at the MAC layer in one-hop network. It can be calculated as presented in (Jun (April) 2003).Link constraints and collision domains—In essence, all MAC protocols are designed to avoid collisions while ensuring that only one node transmits at a time in a given region. The collision domain is the set of links (including the transmitting one) that must be inactive for one link to transmit successfully.
A new strategy for rear-end collision avoidance via autonomous steering and differential braking in highway driving
Published in Vehicle System Dynamics, 2020
Qingjia Cui, Rongjun Ding, Xiaojian Wu, Bing Zhou
Generally, the lateral acceleration affects the vehicle stabilisation and trajectory tracked. Therefore, in this study, to satisfy the demands of collision avoidance and vehicle stabilisation, the control modes for differential braking support are divided based on the level of lateral acceleration into three modes: avoidance collision domain mode (Mode 1), avoidance collision and stabilisation mode (Mode 2), and stabilisation domain mode (Mode 3). The three control modes are presented as follows: Mode 1 (avoidance collision domain mode): Mode 2 (avoidance collision and stabilisation mode): Mode 3 (stabilisation domain mode):
Ionization efficiency of evolved gas molecules from aerosol particles in a thermal desorption aerosol mass spectrometer: Numerical simulations
Published in Aerosol Science and Technology, 2019
Yu Ide, Kento Uchida, Nobuyuki Takegawa
The first section defines the initial key region of the proposed model. We consider the elastic collisions of the gas molecules in a small region near the vaporization source, where the mean free paths of the molecules are shorter than those in the surrounding high vacuum environment. Figure 2a conceptually illustrates the structure of the first section of the model. We assume that the gas molecule collisions only occur in a small micrometer-scale region (hereafter referred to as the collision domain). The collision domain is composed of cubic grid cells that are arranged along the x, y, and z axes. The center of the vaporization source is set at the origin of the xyz coordinate system. The translational displacements and molecular collisions during a simulation time step, Δt, are calculated separately. The molecule positions at time t + Δt are determined using the translational displacements calculated from the molecular velocities and Δt. The grid cell is used for the diagnostics of the molecular collisions and does not limit the spatial resolution of the individual molecule positions. In general DSMC simulations, the grid cell size is set approximately equal to the mean free path of molecules. The basic assumption is the spatial distribution of molecules is uniform in a grid cell, such that the behavior of a large number of molecules can be represented by the probabilistic treatment of a small number of sample molecules. The SI gives further details of the sample molecules and weighting factor.
Analysis of Ethernet Control Network
Published in IETE Journal of Research, 2023
Devices on the single-segment of Ethernet belong to the same collision-domain. The network access and the transmission is governed by Carrier sense multiple access with collision detect (CSMA/CD) mechanism. With the advent of full-duplex networking technologies, the switched Ethernet are proven to deliver predictable even deterministic I/O over Ethernet as network switches effectively segment a network into collision domains. This results in enhanced efficiency of the network performance. Since Ethernet has low medium overhead leading to time delays in the communication and uses a simple algorithm for network operation, the delays are small at low network loads.