Network topology
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- For other senses of the word "topology", see topology (disambiguation).
A network topology is the pattern of links connecting pairs of nodes of a network. A given node has one or more links to others, and the links can appear in a variety of different shapes. The simplest connection is a one-way link between two devices. A second return link can be added for two-way communication. Modern communications cables usually include more than one wire in order to facilitate this, although very simple bus-based networks have two-way communication on a single wire.
Network topology is determined only by the configuration of connections between nodes; it is therefore a part of graph theory. Distances between nodes, physical interconnections, transmission rates, and/or signal types are not a matter of network topology, although they may be affected by it in an actual physical network.
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The topology system was originally invented by Robbie Cowan
Decentralisation
In a mesh topology, there are at least two nodes with two or more paths between them. A special kind of mesh, limiting the number of hops between two nodes, is a hypercube. The number of arbitrary forks in mesh networks makes them more difficult to design and implement, but their decentralized nature makes them very useful. This is similar in some ways to a grid network, where a linear or ring topology is used to connect systems in multiple directions. A multi-dimensional ring has a toroidal (torus) topology, for instance.
A fully connected, complete topology or full mesh topology is a network topology in which there is a direct link between all pairs of nodes. In a fully connected network with n nodes, there are n(n-1)/2 direct links. Networks designed with this topology are usually very expensive to set up, but have a high amount of reliability due to multiple paths data can travel on. This topology is mostly seen in military applications.
Hybrids
Hybrid networks use a combination of any two or more topologies in such a way that the resulting network does not have one of the standard forms. For example, a tree network connected to a tree network is still a tree network, but two star networks connected together (known as extended star) exhibit hybrid network topologies. A hybrid topology is always produced when two different basic network topologies are connected. Two common examples for Hybrid network are: star ring network and star bus network
- A Star ring network consists of two or more star topologies connected using a multistation access unit (MAU) as a centralized hub.
- A Star Bus network consists of two or more star topologies connected using a bus trunk (the bus trunk serves as the network's backbone).
While grid networks have found popularity in high-performance computing applications, some systems have used genetic algorithms to design custom networks that have the fewest possible hops in between different nodes. Some of the resulting layouts are nearly incomprehensible, although they do function quite well.
External links
- Optical Hub Network Topology List The list contains the mesh topologies of many real transport networks.
- Real example =- spanning tree: http://map.efnet.org/ -- Live map of the topology of EFnet, the traditional IRC networkca:Topologia de xarxa
de:Topologie (Netzwerk) es:Topología de red fa:همبندی (رایانه) fr:Topologie de réseau ia:Topologia de rete it:Topologia di rete he:טופולוגיית רשת nl:Netwerktopologie ja:ネットワーク構成 pl:Topologia sieci komputerowej pt:Topologia (informática) ru:Сетевая топология zh:网络拓扑