A network topology is the structure of network layout. 

Logical topology
define how messages are passed from one node to another node within the network.

Logical LAN topologies:

1) Sequential (or logical ring): data is passed from one node to another in a ring-like sequence . - Token passing in token ring and FDDI LANs are examples

2) Broadcast: nodes transmit frames/packets to all other nodes in the network; only the intended recipient processes the data packet.
Ethernet LANs use a logical broadcast topology

3) Point to Point: nodes transmit frames/packets to another node/nodes in the network; only the intended recipient receives the entire frame/packet
Ethernet LANs with switches use a point to point topology.

Physical LAN topology
How nodes attach to the network.

Bus Topology


The medium use is a single wire (backbone)
Other nodes attached via connectors and drop cables.

Advantages of bus topology:
Inexpensive to install (uses less cable)
Easy to add new devices onto the network
Disadvantages of bus topologies:

Disadvantages
Loose connections and breaks in the bus disrupt the entire network.
Early Ethernet LAN were physical bus architectures
Can be expensive to maintain and troubleshoot
A naive user can easily "bring down" the entire bus
Overall maximum length of the bus is limited (10-Base-2)

Ring Topology

All devices are connected in a Ring, closed loop.
Data is transmitted node-to-node in one direction on the ring.
Failing of one link disrupt entire network

Token ring and FDDI LANs have physical ring topologies
It use two rings to communicate both ways and for fault redundancy.


Rings interconnected to form larger rings

Advantages of ring topology:

Very predictable network performance

Slightly more secure than other topologies

Disadvantages of ring topology:

More Expensive hardware

Hardware for ring topologies is less available

Lack support from devices in ring environments

Unique wiring requirements

Complex networking and operational protocol

Star topology
Star topology is one of the most common network setups. Every node connects to a central network device like a hub or switch. The central network device acts as a server, and the peripheral devices act as clients.

Wireless LAN


Wireless Star Network