Computers Networks Topology

Network topology defines the different categories by which we can determine the components and operation of computer networks. Based on these categories, we can divide the network into smaller components and schedule (plan) of these elements. We can also describe the approaches of these smaller components throughout the network. The most common division of network topology refers to the physical topology and logical topology.

Network topology describes the layout and connections between individual nodes (computers, network devices, etc), and trajectory data within a network. The physical network topology plan view showing the of the physical arrangement of the nodes in the network and their connectivity.

We have a variety of physical topology:

POINT-TO-POINT network topology

consists of two nodes and the links between them. These nodes communicate with each other directly.
Point-to-point connection
The connection between nodes can be fixed (permanent) or dynamic (circuit switched, packet switched). Circuit switched the bond at which establishes a communication channel before you can start exchange of data (a telephone call). Packet switched the connection in which pieces of data packaged in packets routed through the shared connection between two nodes that communicate. To connect can use any of the media.

BUS network topology

consists of a central conductor to connected nodes that communicate. This guide has two ends that must be properly terminated to prevent reflections or reject signals and thus to minimize interference in the media.

Bus connection
All data exchanges are sent through the central conductor and the traffic "hear" all other nodes on the network segment. Termination of the bus leading to the cessation of communication between all nodes. As a medium used with coaxial cable.

STAR topology network

comprising a central node (the hub) to which the cables are connected directly to other nodes on the network. The role of hubs usually have a hub (rarely) or switch (more often).

Star connection
Nodes communicate with each other by sending data through the switch. If the hub hub can simultaneously communicate only two nodes. If the hub switch, can simultaneously communicate with multiple pairs of nodes. If the central node stops working, the entire network is not working. Downtime of any other node on the network, except central, does not affect the communication of other nodes in the network segment. This topology, with its subdivisions, is the most common form of connection within a local area network (LAN). As a medium to connect using different types of UTP cable.

Physical RING topology

consists of nodes that are connected only with two adjacent nodes, and the first and last are physically connected to each other, forming a circle.

Ring connection

The data traveling in a circle from one to another node, and typically in only one direction. There is also a dual ring topology (dual-ring) with two connections between any two nodes. Usually used only one ring, while the other serves as a backup in case of failure on the first. As a medium used different forms of copper and fiber optics.

TREE topology 

consists of a central (root) node, which is the highest in the hierarchical arrangement of nodes and nodes connected to it that are on the layer below it. Nodes lower layer again can have on yourself connected nodes still lower layers, etc.

Tree connection
In order let the network had qualities Tree topology is necessary to have at least three layers. The total number of point-to-point link between the nodes will be one less than the number of nodes. As a medium used different forms of copper and fiber optics.

MESH network topology

consists of nodes that can have a direct connection with multiple (partial) or all nodes in the network (full mesh).

Mesh connection
Complete MESH network topology is too expensive and too complex for the application to be used only where absolutely necessary (usually a nuclear power plant) and where there is a large number of nodes that need to connect.

The logical network topology plan view showing the trajectory data traveling between nodes on a network. Logical topologies are commonly associated with the way in which media access for sending data (MAC - Media Access Control). They rely on the application within the communications protocols, and not on their own physical layout of the network.

eg. not necessary that the logical ring topology is also the physical ring topology. When the IBM Token Ring (802.5) topology, the network has the appearance of a ring on the second layer (data link layer), while the first layer (physical) star shape (star topology). Token serves as a sign for a license submitted data to the network and sends a circular from node to node, but not exclusively tied to the physical ring topolgy. It can be applied to others. Logical topologies can be dynamically configured using routers and switches.