Packets are not 500 bytes in size, not even as an average (mean) or median. Many studies of frame length distribution show 64 bytes (for the Ethernet frame) as

Packets are not 500 bytes in size, not even as an average (mean) or median. Many studies of frame length distribution show 64 bytes (for the Ethernet frame) as the most common length, probably because of TCP ACKs. Next most popular is 1518 bytes, the Ethernet maximum, probably because of bulk transfers over TCP. Also, jumbo frames are technically not Ethernet. The IEEE revised the 802.3 spec to increase the maximum envelope from 1518 bytes up to around 2000 bytes to accommodate VLAN stacking and other encapsulating schemes. But jumbos -- usually 9000 or 9216 bytes -- aren't legally Ethernet.