Let me explain.
Network byte order is the standard way of ordering bytes when sending data over the network.
Big-endian: Most Significant Byte (MSB) first, Least Significant Byte (LSB) last.
Example: 0x12345678 → 12 34 56 78
Little-endian: Least Significant Byte (LSB) first, Most Significant Byte (MSB) last.
Example: 0x12345678 → 78 56 34 12
If two machines have different endianness and we don’t standardize, the receiver will misinterpret the value.
Fields like port numbers, IP addresses, sequence numbers, etc., are multi-byte.
If one host sends in little-endian and the other expects big-endian, the values will be wrong.
Example: sending port 0x1F90 (8080)
- Correct (big-endian):
1F 90is 8080 - Misinterpreted (little-endian):
90 1Fis 36895 (completely wrong port!)
Where it’s not necessary
Inside a single machine, byte order usually doesn’t matter because the CPU knows its own endianness.
A single byte has only 8 bits, so there’s no “order” to worry about.