What is a Topology?

The physical topology that a network describes the construction of cables, computers, and other peripherals. Physical topology must not be puzzled with logical topology i m sorry is the method used to pass information in between workstations. Logical topology was debated in the Protocol chapter.

Main varieties of physics Topologies

The complying with sections discuss the physics topologies supplied in networks and other associated topics.

straight Bus

A straight bus topology is composed of a key run of cable with a terminator in ~ each end (See fig. 1). Every nodes (file server, workstations, and also peripherals) are connected to the direct cable.




You are watching: This type of network topology does not use a specific physical layout

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Fig. 1. Linear Bus topology


benefits of a direct Bus Topology

basic to attach a computer system or peripheral come a straight bus. Requires much less cable length than a star topology.

defect of a direct Bus Topology

entire network shuts under if there is a break in the key cable. Terminators are compelled at both ends of the backbone cable. complicated to recognize the problem if the entire network turn off down. Not expected to be used as a stand-alone solution in a huge building.

Star

A star topology is designed through each node (file server, workstations, and also peripherals) associated directly come a central network hub, switch, or concentrator (See fig. 2).

Data top top a star network passes with the hub, switch, or concentrator before continuing come its destination. The hub, switch, or concentrator manages and controls all features of the network. It likewise acts together a repeater for the data flow. This construction is usual with twisted pair cable; however, that can also be provided with coaxial cable or fiber optic cable.


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Fig. 2. Star topology


benefits of a Star Topology

basic to install and also wire. No disturbances to the network as soon as connecting or removed devices. basic to recognize faults and to remove parts.

defect of a Star Topology

Requires much more cable size than a straight topology. If the hub, switch, or concentrator fails, nodes attached are disabled. an ext expensive than direct bus topologies because of the expense of the hubs, etc.

Tree or broadened Star

A tree topology combines characteristics of direct bus and also star topologies. It consists of groups of star-configured workstations associated to a straight bus backbone cable (See fig. 3). Tree topologies enable for the expansion of an present network, and allow schools to configure a network to fulfill their needs.


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Fig. 3. Tree topology


advantages of a Tree Topology

Point-to-point wiring because that individual segments. sustained by number of hardware and software venders.

disadvantages of a Tree Topology

overall length of each segment is minimal by the type of cabling used. If the backbone heat breaks, the whole segment go down. More daunting to configure and also wire than various other topologies.

5-4-3 dominance

A factor to consider in setup up a tree topology utilizing Ethernet protocol is the 5-4-3 rule. One aspect of the Ethernet protocol requires that a signal sent out on the network cable reach every part of the network within a specified size of time. Every concentrator or repeater that a signal goes v adds a little amount the time. This leads to the ascendancy that between any kind of two nodes on the network there have the right to only be a maximum of 5 segments, connected through 4 repeaters/concentrators. In addition, just 3 of the segments may be occupied (trunk) segments if they room made that coaxial cable. A inhabited segment is one that has actually one or much more nodes attached to it . In number 4, the 5-4-3 preeminence is adhered to. The furthest two nodes top top the network have actually 4 segments and also 3 repeaters/concentrators between them.

NOTE: This dominion does not use to various other network protocols or Ethernet networks wherein all fiber optic cabling or a combination of a fiber backbone v UTP cabling is used. If there is a combination of fiber optic backbone and UTP cabling, the ascendancy would analyze to a 7-6-5 rule.The rate of networking switches is vastly improved over older technologies, and also while every initiative should it is in made to limit network segment traversal, effective switching can permit much bigger numbers of segment to it is in traversed with small or no affect to the network.

Considerations When picking a Topology

Money. A direct bus network might be the the very least expensive method to install a network; you execute not have to purchase concentrators. Length that cable needed. The straight bus network uses shorter lengths that cable. Future growth. Through a star topology, expanding a network is conveniently done by including another concentrator. Cable type. The most common cable in colleges is unshielded twisted pair, i beg your pardon is most regularly used with star topologies.

review Chart

physical Topology usual Cable usual Protocol straight Bus Star Tree
Twisted Pair Coaxial Fiber Ethernet
Twisted Pair Fiber Ethernet
Twisted Pair Coaxial Fiber Ethernet



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