A network topology refers to the layout of the computers and devices in a communications network. Network topologies also may be physical or logical. Physical topology means the physical design of a network including design of a network including the devices, location and cable installation. Logical topology refers to how data is actually transferred in a network as opposed to its physical design. Now lets see in detail diffrent types network topologies.
Types of Network Topologies
The term Topology refers to a connected layout of devices shared in a network. Now we shall go ahead in the discussion of the standard Topologies from the computer networking.
An imagination of the shape of the network or the structure of virtual architecture is considered to be the topology. The structure or the shape is not mandatory to implement the exact physical layout of the present devices in the network. For instance the Home LAN shall be constructed in a circle physically and does not really need to determine the circle in the topology too. They shall be categorized as follows;
- Star Topology
- Ring Topology
- Bus Topology
- Tree Topology
- Mesh Topology
- Hybrid Topology
A solid or complex oriented network shall be built by the association of the hybrids of one or more of the basic scheduled topologies mentioned above.
1. Star Topology
This Topology is mainly considered for the home networking. It normally facilitates a model of central connection called the HUB and this hub may not definitely be a HUB, it may consist of Router or a Switch or a Hub itself. The devices are connected to the Hub through the UTP Ethernet. A comparative study with the bus topologies the star topology consist of more usage of cables and the breakage of the network does only pull one computer network access down and not the complete set of LAN anyhow on the failure of the hub the entire network fails.
The general advantage of the Star Topology describes ease of installation and wiring without any disruptions caused to the network while connecting or disconnecting of any devices. They are easy to connect, remove or detect faults in and among the devices or the network.
The general Disadvantages of the Star Topology state’s some such as the increase in the necessary of the cable length. The Hub or the device used as hub fails to concentrate then the nodes attached shows to be inactive or disabled automatically. These topologies are considered to be more expensive than the existing linear topologies increasing the cost value of the concentrators.
The protocol access for the Star Topology is recognised to be the LocalTalk or the Ethernet. The token Ring uses a similar kind of topology known as the Star-Wired Ring.
Star-Wired Ring: The outlook appearance of the Star-Wired Topology is to be the same model of the Star Topology. The MAU of the Star-Wired ring consist of the wiring that focuses on the transfer of information from one device to another in a ring or a circle as explained in the figure below. A Star-Wired Topology is been used in the Token Ring protocol.
2. Ring Topology
Each and every device in this category has two exact neighbours for communication purposes and instances in the Ring network. The messages distributed travel through the ring in the same direction either clockwise or anti-clockwise failing the entire network on the account of breakage. If any cable or device is broken in the connection of the loop then they take the advantage of breaking the entire network. A typical usage of the FDDI, SONNET or any Token Ring topology is used for the implementation of the Ring Network. These kinds of topologies are enhanced in schools and some office enterprises.
An interesting topology in the network topology is the network topology. On the outline it looks like the group of computers which are connected in the form of circle. The network is redundant and collision-free topology. Being a ring, there are no terminator devices in this topology. The node gives information of data about destination address. According to the destination address given in the data sent in the frame it reaches the destination address and the data is given to destination from the frame. This ring topology is of another kind which is known as Dual-Ring topology. The second ring is being used when the first ring fails.
3. Bus Topology
These are networks and are not confused along with the Bus of the computers. These Networks are used as a common activity for the connection of the devices in the network. They are also known as the backbone of the networks. A shared connection shares the communication with another device by the medium through a single cable; they attach or tap along with the interface connector. A broadcast message is sent through the wire set in the network by the device that is need of communication and only the intended recipient formally receives, accepts and processes the messages.
Ethernet Bus topologies are in action with comparatively less usage of cables and are relatively easy in the process of installation on comparison with the alternatives. The cabling options differ as 10Base-2 (ThinNet) and 10Base-5 (ThickNet), as both are famous Ethernet cables for bus topologies. The bus topologies are best enhanced and reported with results in a limited active devices environment. If in the same case more number of computers are connected then the performance may be affected as they are only restricted to a limited number of computers. An additional problem such as the failure of the backbone shall result in the breakage of the entire network and may enter the stage of becoming unusable.
Advantages: The computer of the peripheral shall be attached easily with the linear bus. The requirement of the length of cable is less when compared with the Star Topologies.
Disadvantages: A small break in the cable shuts the entire network. The backbone cable requires terminator at the both ends. A difficulty arises in the understanding of the problem in the shutting down of the system as a whole. This type of solution is never recommended for a stand-alone solution for a large building using large number of networking area.
4. Tree Topology
Integrating multiple start topologies combined with the bus topology is known as the Tree topology. To define it easily the hub is the only device that connects to the tree directly, and defined as a each hub functioning to be a root from the tree of devices. The hybrid approach of the bus and the star topologies enhances the future of the network expandability that is proposed to better than the bus topology and the star topology. Whereas in the bus topologies the numbers of devices are limited due to the generation of traffic in broadcasting and in the Star topologies there are only limited number of hub points.
Advantages: Individual segments including Point to Point wiring features. Supported by different vendors and several hardware’s.
Disadvantages: The length of the overall segment is limited by the type of cable used. The entire system goes down upon the breakage of the backbone line in the system. The configuration is considerably more difficult other than other topologies.
5. Mesh Topology
This is a topology that involves the concept of routes. The mesh topologies unlike the other topologies shall take any path from the source to the destination through several options as the messages sent in other network uses the same passage. In comparison with the ring topologies the messages though having a two cable path they travel only through one direction. Some of the Wide area network associate deploys the Mesh routing.
The connection of every single node together is specified as the Full Mesh topology. This shall create the most reliable and redundant networks especially for the large networks used in many organisations. Even though if one link or the other fails they should be able to get connected and linked through the other for the transferring of the data. The linking specifies more connect-ability issues creating a technique of involving a partial mesh topology for restriction of the calculation of the wires used for the linking of the computers for every device on a network.
The Partial mesh topology is more or less like the Full-mesh as the only difference is the connection of every device with another device on the network is not made instead implementing few routes alternatively. The partial-mesh topologies is been adopted for redundant connection and mostly in WAN’s between routers. A full mesh is defined as the part of a Mesh network where the complete device connects as depicted in the illustration below, some devices may also connect through indirect way empowering the partial mesh networks.
6. Hybrid Topology
A hybrid topology is one where one or more network topologies exist.
Scenario 1: scenarios in which two different topologies connected together still can observe and maintain the same basic network character and hence cannot be considered as a Hybrid Network. For instance a tree network being connected to the same tree network is still the tree network. Therefore the hybrid network is said to be absolute when the two basic network topologies are associated and the topologies resulted failing to meet the basic topology definitions. Example: Two star topologies associated exhibits hybrid topology networks.
Scenario 2: two basic network topologies connected accrues the Hybrid Topology.