Structure or telecommunication network form is very varied, especially confirmed by need and local demography. On the first telecommunication network development, there are two basic network forms, that is mesh network and star network. At this moment already develop to the other network forms, are bus network, ring network, and tree network.
If on n network station equipment (telephone or central), every station direct connected to each station with stand-alone line (figure 1.1 (a)), then the configuration is called mesh network. On this network, every station needs n-1 line to connect to every station, so that the total line that need on mesh network is 1/2n (n -1) line.
Figure 1.1 (a) Mesh
Mesh network practically is match for system with n total small and short lines, example, for little system that serves several telephones in one office. If n increase (big enough) and the lines become long, using mesh network became very expensive. Example, system with 10.000 customer stations will need at least 50 million lines.
On telephone system, two-way communication between costumers and central that to be connected each other and this two-way conversation must execute in the same time. This case only performed if on network found one station that function as switch central (telephone central), terminal all customer telephone line. Network with this configuration, is called star network. Such as showed on figure 1.1.(b).
Figure 1.1. (b). Star
If a customer far away from central or coverage area is very large, then using star network became inefficient economically because a line become long and cost line will be expensive. For handling this condition then need implemented combination of mesh network with star network, such as showed on figure 1.1. (c).
Figure 1.1. (c). Mesh & Star
Beside a mesh network and star network, all equipment station can also connect to one single line, shaping a bus, such as showed on figure 1.1. (e), or shaping a ring or loop such as showed on figure 1.1(d). Bus network and ring network form used on data communication with data transmission performed via jointly line with high-speed then speed on each individual station (terminal). Example application that using bus network or ring network is LAN (Local Area Network).
Figure 1.1 (d) Loop
Figure 1.1. (e). Bus
If network coverage area already very large (one country or more), then network form became very complex and generally invented become hierarchy, and is called tree network.
Figure 1.1. (f). Tree
