Definition of topology
Network topology किसी भी नेटवर्क की संरचना, उपस्थिति या लेआउट को दर्शाता है कि कंप्यूटर संचार नेटवर्क के भीतर कंप्यूटर केबल, नोड और अन्य घटक कैसे तार्किक और शारीरिक रूप से जुड़े हुए हैं।
शारीरिक रूप से टोपोलॉजी एक नेटवर्क को शारीरिक रूप से निर्धारित करने के तरीके को दर्शाता है, और तार्किक टोपोलॉजी का वर्णन है कि डेटा वास्तव में नेटवर्क के माध्यम से कैसे प्रवाहित होता है।
A bus topology is a multi point data communication circuit that makes it relatively simple to control data flow between and among the computers because this configuration allows all stations to receive every transmission over the network.
बस टोपोलॉजी का उपयोग ज्यादातर तब किया जाता है जब नेटवर्क इंस्टॉलेशन छोटा, आसान, सरल और अस्थायी होता है।
Features of the bus topology
- This is multi point configuration.
- Adequate signal to noise ratio should be maintained.
- The signal should not be too strong.This is necessary to avoid possibility of signal distortion.
- The is called as signal balancing which is not an easy task at all.
Advantages of Bus topology
- A bus topology is easy to understand,install and use for small network.
- The cabling cost is less as the bus topology requires the least amount of cable to connect the computers.
- A bus topology is easy to expand by joining two cables with a BNC barrel connector.
Disadvantage of bus topology
- Heavy network traffic slows down the bus speed.In the bus topology,only one computer can transmit and others have to wait till their turn comes and there is no coordination between computers for reservation of transmitting time slot.
- The BNC connectors used for expansion of the bus attenuates the signal considerably.
Ring Topology में, प्रत्येक कंप्यूटर अगले कंप्यूटर से जुड़ा होता है, पहला कंप्यूटर से जुड़ा होता है।
They are used in high-performance networks where large bandwidth is essential,e.g,time attractive features such as video and audio.
A ring topology is a multi point data communication network where all stations are interconnected in random series to form a closed loop or circle.
The message flow around the ring in one direction.there is no termination point because there is no end point to the ring.Some ring topology networks do token passing.
A short message called a token,is passed around the ring until a computer wishes to send information to another computer.
Features of ring topology
- The data are transferred is a manner bit by bit around the ring.
- It may be noted that each repeater will regenerate and re-transmit each bit.
Advantages of ring topology
- No one computer can monopolies the network because every computer is given equal access to the token.
- The fair sharing of the network allows the network to continue function in a useful ,if slower,manner rather than fail once capacity is exceeded as more users are added.
Disadvantage of ring topology
- Failure of one computer on the ring can affect the whole network.
- It is difficult to troubleshoot the ring.
- Adding or removing the computers disturbs the network activity.
- It is necessary to take preventive measures to deal with the time Jittery.
- If any link breaks or if any repeater fails then the entire network will be disabled.
In the star topology all computers are connected to a central device called a hub. In star topology, each computer communicates with a central hub that sends instructions to all computers.
Hub – The hub in a broadcast star network can be active or passive.
An active hub generates electrical signals and sends these signals to a self-connected computer. It is also called multi-port repeater. The active hub requires an external power supply.
Passive hub –
A passive hub is a wiring panel or punch down block which acts as a connection point.It does not amplify or regenerate the signal.Passive hubs do not require electrical power supply.
Advantage of star topology
- it is very reliable – if failure occurs in one cable or any device then all the others device will continue to work.
- it is very high-performing as no data collisions can occur.
Disadvantages of a star topology
- it is very expensive to install as this type of network uses the most expansive cable.
- in this topology required extra hardware like (hubs or switches) which adds to cost.
- if any hub or switches fails, all the devices connected to it will have no network connection.
In the mesh topology,every device has a dedicated point-to-point link to every other devices devices.
The term of dedication means that the link carries traffic only between two devices it connects.
A fully connected mesh network therefore has n(n-1)/2 physical channels to link devices.
Advantage of mesh topology
- The use of dedicated links guarantees that each connection can carry its own data load,thus eliminating traffic problems.
- A mesh topology is robust because the failure of single computer does not bring down entire network.
- It provides security and privacy because every message sent travels along a dedicated line.
Disadvantage of mesh topology
- Cabling cost is very expensive.
- The hardware required to connect each link input/output and cable is expensive.
- Point to point links make fault diagnose easy.
Tree topology एक विशेष प्रकार की कंप्यूटर संरचना है जिसमें कई कंप्यूटरों को पेड़ की शाखाओं के व्यवस्थित रूप में परस्पर जोड़ा जाता है।
Advantage of tree topology
- Tree topology allows two or more computers from one hub to connect to the hub.
- It allows the network to isolate and priorities communications from different computers.
Disadvantage of topology
- If failure occurs in any hub then system breaks down.
- The cabling cost is more.