A topology is a physical structure of a network. Star topology is one the most common topology in the LAN. Other topologies are Ring topology, Bus topology and Mix topology.
In start topology every computer is connected to a central point. That central point may be a HUB or a switch. The media used in this topology is twisted pair cable. The communication devices used is a LAN card. Every computer must have a LAN card and a twisted pair cable. One end of the cable is plugged in LAN card and the other is connected with the HUB or a switch. If we have a domain then the Server should also be connected with the HUB or switch. Every source, which we may share, should be connected to one of the computers (e.g. printer).
Star topology is considered one the best topology. The advantage is that if any computer is not working or any cable is not working then the whole network will not be affected. But the disadvantage is that it is expensive form of network as every computer required a separate cable to form the network. The other disadvantage is that if the HUB is not working, the whole network will be dumb.
In start topology, all devices are connected to a hub. All the data passes through the hub and hub is a central connecting point. As all the data passes through a central connecting point (hub) so a problem can occur here known as bottle-necks but the biggest advantage of star topology is that its installation and management is very easy.
When a packet comes to the hub then it transfers that packet to all the nodes connected through hub but only one node at a time successfully transmits it. In this case if you see carefully then you will come to the point that arrangement in this topology is logically a bus but physically it looks like a star.
Advantages and disadvantages of Star Topology are mentioned below.
Advantages: (1) If we use small number of devices in this topology then data rate will be high. It is best for short distances, but for long distances other topologies are better than this.
(2) If one workstation fails then it does not effect on overall communication. While in other topologies if one workstation fails then it affects overall communication.
Disadvantages: (1) Main problem is that, if an error occurs on the hub then all the stations cannot communicate with each other. (2) Improper use of link capacity.
Star topology is look like a star but not exactly a star. Star topology is the older topology used in networking. The idea of star topology comes from Telecommunication system. In telephone system all telephone calls are handled by central switching station. Similarly in star topology central device Hub is used. Hub is responsible of managing all activities of the network. All nodes (file server, workstations and peripheral devices) in star topology are directly connected to hub. Connector is also use in place of hub. Different types of cables are used to connect nodes such as twisted pair, coaxial cable and fiber optics. Star topology is very easy to extend and modify the network. It is easy to install and manage.
Due to the centralization in star topology it is very easy to monitor and manage the network. Like bus topology the fail of single computer will not affect the whole network. Star topology also has some drawbacks. It there is any problem in central device Hub or connector then network fails. When we are going to extend our network then we need more cable and result in more intricate installations. It is expansive due to cost of connector or hub than other simple topologies such as bus.
Star topology is one of the most and very common topologies of computer network. Switch or hub is the main central node of the star topology based networks. Hubs or switch acts like a conduit used to transmit and transfer messages. The networks built on the basis of star topology are called star networks. There are two types of star networks. One is active star networks and the other is passive star networks. In active star networks the central node is active and is capable to tolerate and prevent echo problems. While in passive networks, the central node is not active because of which the attached nodes have to tolerate and prevent all echo related problems. In star networks ratio of network failure is little than others as all of the systems are always connected to central switch or hub.
Star topology is very much easy to set up and expand. Non-centralized failure never affects whole system. Faults can easily be detected in star networks. There is no need of packets to travel through unnecessary nodes, so the packets can quickly transfer over the network. Performance wise star networks are very good. But star networks are expensive to build up as extra hardware is required. And the major disadvantage of star networks is that if the central node (either switch or hub) fails, the whole network will get down.
In a start configuration of computer network, there is a host computer which is attached to local computers through multiple communication lines. The computers are not connected to each other and can not communicate directly with each other. The local computers can only communicate only via through the host computer. The routing function is performed by the host computer which centrally controls communication between any two local computers by establishing a logical path between them. As like with any communication scheme, star topology has its own pros and corns. Some of the advantages of Star topology are: 1) The number of communication lines required to connect 'n' local computer is always 1 less he number of nodes, i.e. Communication line requires 'n-1' lines are required. 2) If any of the local computer in the network breaks down then there is no effect on the whole network and the rest of the network is unaffected and works fully functional 3) Transmission delays do not increase between two local computers if new local computers are added in the network because any two local computers are connected only through two links. An obvious disadvantage of star topology is 1) The whole network depends on the Host computer. If the host computer fails or breaks down then the whole network crashes.
