Jeremy’s IT Lab lecture video:
Day 06 - Ethernet LAN Switching (2)
Refer to:
Ethernet Frame General Information
Ethernet Frame General Information
The Preamble + SFD (which is 8 bytes total, 7 bytes in the Preamble and 1 byte in the SFD) is usually not calculated whe
n counting bits in the Ethernet header
- So, instead of the Ethernet header being 26 bytes (Preamble + SFD + DST MAC + SRC MAC + Type/Length + CRC)
(8 + 6 + 6 + 2 + 4) = 26 bytes- The actual size of the Ethernet header + trailer is 18 bytes (DST MAC + SRC MAC + Type/Length + CRC)
(6 + 6 + 2 + 4) = 18 bytes
Link to original
- The minimum size for an Ethernet frame (Header + Payload [Packet] + Trailer) is 64 bytes
64 bytes – 18 bytes (header + trailer size) = 46 bytes- Therefore, the minimum payload (packet) size is 46 bytes
- If the payload is less than 46 bytes, padding bytes are added
- ie.
34-byte payload packet + 12-byte padding = 46 bytes