If the transmission line is very fast and the wire is very long, it is possible that two distant stations can complete their transmissions at the same time but not see the collision that occurs in the middle because they are done transmitting before the other message arrives. Therefore Ethernet cables have a maximum length to ensure that a station will see any collision that occurs. The time for a signal to travel the full length of the cable must be less than twice the time required to send a frame. Ethernet is a bus network using coax cables up to 500m in length with at least 3m between nodes. The twisted pair wires are connected to an Ethernet hub in a star topology.
Ethernet switches buffer and transmit the data only on the lines necessary.
Token Based LANs Token Ring and Token Bus networks do not have any collisions. To avoid collisions, the network has one logical token. Only the station that currently holds the token can transmit on the network. If that station has something to send, it can do so once it receives the token. If the station has nothing to send, it will immediately forward the token to the next station.