-Topology is of two types: Physical and logical.
-Physical Topology defines how the network is physically connected.
-Logically Topology defines how data is transferred within the network
Physical Topology: There are 5 types of physical topology.
1. BUS Topology (very old types not used anymore)
-Every computer is directly connected to central cable called BUS.
-The BUS acts as the communication medium for all network computers.
Advantages
It is very cheap and affordable.
Disadvantages
1. Very low speed (10mbps)
2. Number of computers is limited (Max 100)
3. Difficult to physical setup.
4. In case of cable breakage difficult to locate area of problem.
5. In case of cable breakage entire network will break.
2. Ring Topology (old types not used anymore)
-In this network the fist computer is connected to the second, second to third and finally the last computer is connected back to first computer.
-Ring can be of 2 types;
a. Single Ring: Data is sent in single direction only. (Clockwise or counter clockwise)
b. Dual Ring: Data is sent in both directions to increase data flow speed.
Advantages
- No terminators are required.
- It is slightly fault tolerant when compared to BUS.
- Disadvantages
- Very low speed. (10mbps)
- Less computers. (Max 100)
- In case of cable failure the network will either function slowly or completely crash.
3. Star Topology (Most common & popular now a days)
-In this network the central cable has been replaced by the central device called HUB/Switch.
-The central device allows more computers to be connected and supports higher speeds.
Advantages
- High speed networking.
- More number of computers.
- Intelligent device auto manages the network.
- Easier to located area of problem.
- In case of cable failure only a single computer will be affected.
- Disadvantages
- If central device fails entire network will crash.
- Lots of cabling is required.
4. Mesh Topology (old types not used anymore)
- In this network all computers are directly connected to every other computer in the network.
- Chances of this network crashing is almost impossible.
Logical topology
Logical bus
- This is the commonly used logical topology
- In this, when one computer sends a message it can be seen by all computers but only the destination computer will use it.
- We can identify a logical BUS if we can send message at any time.
Logical Ring
- This is used in token ring network.
- In this, only one computer can send at a time. Other computers must wait.
- We can identify logical ring if there are separate connections for sending and receiving.
Cellular (wireless)
- This is the same as logical bus.
- The only difference is that no physical connection is required.
- The range of the WAP device is called cell. We can interconnect two or more cells.
- Computers can be moved from one cell to another and still be able to communicate in the network.
