Due to the limitation of CSMA/CD algorithm, the frame length of Standard Ethernet should not be smaller than 64 bytes, which is determined by the maximum transmission distance and the working mechanism of collision detection.
The use of a minimum frame length prevents situations in which a station finishes sending the last bit of a packet, but the first bit of the packet has not arrived at the remote station. At this point, the remote station senses that the line is idle and begins to send data, leading to a collision.
The upper layer protocol must ensure that the minimum length of the Data field in an Ethernet frame is 46 bytes. If the length is less than 46 bytes, the upper layer protocol must fill the redundant bits to make the length of the Data field reach 46 bytes. A 46-byte Data field, a 14-byte Ethernet frame header, and a 4-byte verification code form a 64-byte minimum Ethernet frame.
In an Ethernet frame, the maximum length of the Data field is 1500 bytes. The maximum transmission distance depends on the elements such as line quality and signal attenuation.