A physical topology is a method of placing a network component, in which case it includes the location of the device and cable placement, while the topology logic is an overview of how data flows on a network without having to pay attention to the physical design The network.
A network topology can be classified into eight types of topology, namely peer to peer, linear, bus, star, ring, mesh, tree and hybrid. And in this article will focus to discuss one of the eight types of topology, namely the star topology. See the description of the star topology and its advantages and disadvantages below.
Understanding of Star Topology
A star topology, also known as a Star network, is one of the most frequently used computer network topology. The concept of star topology like a star with the central point is the center device and there are five computer devices that are the host that connect directly to the center point or the center device so as to produce the shape Like a star. This of course is limited to an overview of the concept of a star topology, and the number of hosts that can be connected is also not limited to five hosts.
What is meant by the star topology is that all computers are interconnected through a central device. In the star topology all data sent from a computer to another computer must be through the central device first.
The central device is a network device such as a hub, switch or computer. The main function of this central device is to manage and control all functions of the network, and the central device can also function as a repeater for the data stream.
Characteristics of Star topology
Star topology has a characteristic that is on each host computer has its own cord that is connected directly to the device center hub, switch, multipoint repeater, or even Multistation Access Unit (MAU) through a point-to-point system.
This star topology is usually implemented on home network or office, and usually use Unshielded Twisted Pair (UTP) type cable, but also can use type of fiber optic cable and coaxial cable.
How the Star topology works
Let's assume that you have a computer network with a star topology consisting of several computers that are connected to a hub center device or switch. The Switch in this case saves the Content Addressable Memory (CAM) list on its Memory. The CAM stores the entire address of the device connected to the switch.
For example case, when computer A wants to transmit data on computer B, then computer A will send A message to the switch. The switch will check the address to be addressed by using the CAM list, after specifying the location of the computer to be addressed, the switch will forward the message to the destination computer, in which case it is computer B.
Unlike the hub, because the hub doesn't have memory to store the data of the connected device. Therefore when computer A will send A message to computer B, then the hub will announce "Hey all the devices connected to me, I received a package with this address. Who among you have this address? ". The procedure is called ARP (Address Resolution Protocol) and the network protocol is where the hub can find the address of the package to be addressed, then pass it on.
Advantages of Star topology
Star topology has a variety of advantages that it has so widely used in office network. Advantages of star topology, namely:
1. Ease of installation
To do the installation on the star topology is fairly easy, you just pull the cable from the host computer to the central device. In addition you can also use the cable type twisted pair to make it much easier.
Another advantage offered by star topology is the flexibility that is offered. You can easily add or subtract host computers, without affecting data traffic on other computers. This is what makes the star topology suitable for applied on large-scale networks
3. Accessibility in terms of troubleshooting
With star topology you can easily determine which device is problematic, because each computer has its own connection path. Additionally, if a problem occurs on one of the hosts, it will not affect the data traffic on the network. It is the biggest drawback of star topology.
Lack of Star topology
Although with a variety of advantages owned by this star topology, there is a negative impact that it generates, which then it is the disadvantage of this star topology. The disadvantages of the star topology are:
1. Dependence on a central device
One drawback of the star topology is the host dependency on the central device. So if the central device crashes, then the entire network will be affected, because this central device is the only data path the host has to connect to other hosts.
2. The cost is quite large
The cost required to do the installation of star topology is quite large when compared with the bus topology, because in the star topology every host need one cable fruit to be able to connect to the center device. A central device should also be a high-quality device, as the data transmission speed on the network is influenced also by the central device type used.
That is some explanation about the understanding of star topology and its characteristics, advantages and disadvantages. Understand the science of the topology help you in terms of designing a computer network and understand the concept of a network device.