In a network, when two or more stations attempt to transmit a packet across the network at the same time, a packet collision occurs. This is not uncommon in a shared medium such as an Ethernet that has many computers in the same network segment. When a packet collision occurs, the packets are either discarded or sent back to their originating stations and then retransmitted in a timed sequence to avoid further collision. Packet collisions can result in the loss of packet integrity or can impede the performance of a network. Also see CSMA/CD.