Network Topologies
What is a Topology?
A Local Area Networks’ physical layout of its resources is called a topology. The connection of a topology always involves two or more computers. A network's topology affects its capabilities. The type of topology used will determine the network growth, the capabilities of the equipment, the type of equipment needed and the network management.
Physical Topology
A physical topology is the physical layout of devices on a network. Every LAN has a topology, or the way that the devices on a network are arranged and how they communicate with each other. The way that the workstations are connected to the network and the physical structure of the network is called the physical topology.
A network's logical topology is not necessarily the same as its physical topology. For example, twisted pair Ethernet is a logical bus topology in a physical star topology layout.
Logical Topology
The logical topology, in contrast, is the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without regard to the physical interconnection of the devices.
Logical topologies are bound to the network protocols that direct how the data moves across a network. For example, IBM's Token Ring is a logical ring topology, but it is physically set up in a star topology.
Standard Topologies
In the Bus Topology, all devices are connected to a central cable called the backbone. These networks are inexpensive and east to install on small networks. When a sending machine transmits its data, it is transmitted to all devices on that segment. Due to the nature of transmission on a bus network, both ends of the cable or segment must be terminated. Terminators absorb all signals that reach the segment ends. Only one computer at a time can send information on the bus topology. “Because of this limitation, the number of computers attached to a bus network can affect network performance” (p. 51 Tomsho). If a break in the connection occurs, both ends of the network must be sealed with a terminator in order to avoid signal bounce. If cable failure occurs, then the computers can still act as standalones, but “no network communications are possible” (p. 51 Tomsho). Ethernet systems use the bus topology.
“Network topology is the arrangement of the various network elements such as node, link, of computer network. Basically, it is topological structure of a network which ether be physically or logically.”
Wireless networks – While the term wireless network may technically be used to refer to any type of network that is wireless, the term is most commonly used to refer to a telecommunications network whose interconnection between nodes is implemented without the use of wires, such as a computer network. Wireless telecommunication networks are generally implemented with some type of remote information transmission system that uses electromagnetic waves, such as radio waves, for the carrier and this implementation usually takes place at the physical level or “layer” network.
To attempt to define a network in a few sentences would be a fool’s errand. A network could be seen as simply a grid of interconnecting connections between multiple bodies. However when this vision is applied to real-world systems, they all start to differ. There is not anything that exists in the universe that is not part of a network. A network is the result of different parts or members which have similarities in parts of their identity. This similarity that they have in common, they will also have with other bodies forming a network between them. Most of these factors of identity are different from those of most others. As a result, each factor will be in common with different other members of different networks. Each factor includes this body in a multitude of networks. This means that no one thing is in one and only one network, but is included in many.
The Physical Layer is the layer that is responsible for the hardwired connection, this is in charge of the cables and device layouts (Tetz, 2011). Without this layer no devices would be able to connect to that network. This includes wireless as Wi-Fi cards belong to the physical and data link layers (Capano, 2014). The physical layer also takes the
All computers are connected to a hub, switch or router. Require more cabling, but failure of one node does not break down the network.
A switch can be used to make various connections. Ethernet, Token Ring, and various other types of packet switched network segments together to form a heterogeneous network operating at OSI Layer 2.
One believes the nature of logic is how we each deal with a situation and how we decide what the right thing to do is and how we come to certain conclusions about a situation. We all have had experiences in our life that contribute to what we feel is logical or not logical.
The Open Systems Interconnection (OSI) reference model is essential to the world of computer networking. The model was created in 1977 by the International Standards Committee, in response to a difficulty that was facing computer networkers at the time (Shelly, Cashman, and Serwatka 142). In order to understand the difficulty, one must first realize that computer networks consist of computer hardware, the software that is to be used in conjunction with this hardware, and the medium (such as wiring or cabling) that will interconnect the computing devices that are in the network. The computer networker’s job is to determine which hardware, software, and medium types will create the network that will best suit his client’s needs. Then, the networker must combine these elements into a functional system of interconnected computers (Fortino and Villeneuve 112). It was in attempting this latter task that the computer networker of the late 1970s often found himself in a pickle. The problem was that each vendor of computing equipment had developed his own unique set of products; products that were incompatible with the products of other vendors. This incompatibility made it very difficult for a computer networker to combine the various network components into an operational computer network (Stamper 27).
The OSI network reference model was developed by the International Organization for Standardization (ISO) to facilitate communication between networks by keeping certain standards open rather than proprietary (Serpanos & Wolf, 2011). Each layer is stacked with the physical layer as the lowest and the application layer as the highest and one can think of each layer as containing stacks of protocols that make network communications function (Serpanos & Wolf, 2011). A protocol is a set of rules written in a common language that allows computers to communicate with each other. Each communication network is a node and the corresponding layer on each node communicates with each other.
4. Each computer is connected to a central point, this topology requires a great deal of cable in a large network installation and could cost a great deal of time and money for installation.
It just doesn't get much simpler than the physical bus topology when it comes to connecting nodes on a Local Area Network (LAN). The most common implementation of a linear bus topology is IEEE 802.3 Ethernet. All devices in a bus topology are connected to a single cable called the bus, backbone, or ether. The transmission medium has a physical beginning and an end. All connections must be terminated with a resistor to keep data transmissions from being mistaken as network traffic. The terminating resistor must match the impedance of the cable.
When we look at the differences between logical design and physical design of a network it is easy to think of it as the logical as the functional part and physical as the seeing it part. With that stated there is more to this than just the functional and seeing parts. In order to understand the differences from one to the other, we need more information. In the following paragraphs I will try to outline what makes up the differences between logical and physical design of a network.
Next, the writer goes over the second type of network architecture - the TCP/IP reference model, the granddaddy of the wide area computer network. This architecture allows the connection of multiple networks seamlessly. The architecture is flexible and capable of running even if some of the subnet hardware is destroyed or non-functional as long as the source and destination machines are functioning. In a similar fashion to the OSI model, the TCP/IP model has layers as well. In this case, we have four layers: the link
Both Bridges and Switches work on the data link layer of the OSI Model. However, switches are more advanced. Discuss how a switch has an advantage over a bridge in a network then elaborate more on the technology implemented in switches to control broadcast domains.
The term Topology refers to the physical or logical shape or layout of a network. Communication between different nodes within a network is determined by its topology. Mesh, Bus, Ring and Star are four of the most common network topologies, each with advantages and disadvantages in relation to each other.