Notes
Network topologies
Bus topology
- Nodes are directly connected to common linear or branched half duplex link called bus.
- Passive topology
- Requires proper termination at both ends to avoid reflection
Advantages :
- Easy to install
- Used in small networks
- Less cabling cost
- Easy to expand
Disadvantages :
- Can’t handle heavy traffic
- BNC connectors used for expansion attenuates signal
- Improper termination can reflect signal
Ring topology
- Each nodes connect to exactly two other nodes
- Active network
- Message flows around ring in one direction
- No termination as there is no end to ring
- Token passing : it allows station to transmit when it holds token
- Sequential manner transmission
- Each node has to recreate packet
Advantages :
- Equal access to token
- No standing waves produced
Disadvantages :
- Failure of one node can affect whole network
- Difficult to troubleshoot
- Adding and removing computers disturbs network activity
Star topology
- All nodes are connected to central hub or switch
- No direct communication among computers
- Concentrated network
- Hub send packets to destination
- Active or passive depend on central hub
Advantages :
- More devices can be connected in large distance
- Isolated network due to central hub management
- High reliability
- Easy to expand
Disadvantages :
- If central hub fails then network is down
- High cabling cost
Mesh topology
- Every node connected to every other node
- Dedicated link
- n(n-1)/2 physical cables are required
- Passive network
Advantages :
- High reliability
- Data security because of dedicated link
- Easy to troubleshoot
Disadvantages :
- High cabling cost
- Expensive
- Installation and configuration is difficult
Tree topology
- Arranged like branches of tree
- Variation of star topology
- Central hub is connected to many other hubs
- Parent child topology
- Active network
Advantages :
- Large distance covered
- Allows network to isolate
- Signal can go for long distance
Disadvantages :
- Failure of central hub breaks down
- Cabling cost is more
Hybrid topology
Mixture of all topologies like bus and ring
