Physical layer-
Bus- Every workstation is connected to a single cable. Every host is directly connected to every other workstation
Ring- Computers and other network devices are cabled together so that the last is connected to the first.
Star- Most common- A central cabling device(switch) connect computers and other network devices together. Star and extended star.
Mesh- Every network device is cabled together with connections to each other. Redundant links increase reliability and self-healing.
Hybrid- Ethernet uses a physical star layout and the signal travels end to end.