ccna 200-301 official cert guide library by wendell odom

ccna 200-301 official cert guide library by wendell odom.The network topology (Topology) defines the structure of the network. There are two types of network topology: a physical topology, which is the geometric form in which the actual wiring or devices are connected to each other; and a logical topology, which defines how the media accesses the data sent by the host.1. physical topology According to the different physical topology, the network can be divided into three basic types: star network, ring network, and bus network. (1) Bus type topology. All stations in the network share a data channel with end nodes at both ends of the bus, as shown in Figure 2-1-1. Bus type networkSimple and easy to install, requires the shortest cables to be laid, low cost, and failure at one site does not usually affect the entire network, but failure of the media can bring the network down. Bus-based networks are less secure, more difficult to monitor, and adding new sites is not as easy as a star topology network. Therefore, bus-type network structure has now been largely eliminated.(2) Ring topology. Ring-type network structure of the sites through the communication medium connected into a closed ring, as shown in Figure 2-1.2. Ring networks are easy to install and monitor, but the capacity is limited and it is difficult to add new sites after the network is completed. Therefore, ring network structure is basically not used nowadays to form LANs.(3) Star topology. Each site is connected to the central site through a point-to-point link, as shown in Figure 2-1-3. Star network is easy to add new sites in the network, the security and priority of data is easy to control, easy to achieve network monitoring, a site problem, will not affect the operation of the entire network, but the failure of the central node will cause the entire network down. Star network structure is now the most commonly used network topology.Figure 2-1-1 Bus Type TopologyFigure 2J-2 Ring Topology Figure 2-1-3 Star TopologyBased on these three types of network structures, networks with other types of topologies such as extended star, hierarchical, and mesh can be combined, as shown in Figure 2-1-4shown. Figure 2-1-4 Other Types of Topologies2. logical topology The logical topology of a network is the way in which the hosts communicate with each other through the transmission medium. The two most common logical topologies