Description
Combine high and low octets as high × 256 + low to obtain a 16-bit network-order word.
Packet headers encode several meanings in fixed-width fields. Bit positions, network byte order, and reserved values must be distinguished from validation of an entire message.
Combine high and low octets as high × 256 + low to obtain a 16-bit network-order word.
When to use this tool
Use IPv4 Header Checksum Word Contribution when you need to decode or encode one explicit packet field.
How to use the tool and how it works
- Enter high, low. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read word. Use the output convention below.
Combine high and low octets as high × 256 + low to obtain a 16-bit network-order word.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| high | High | Required. Safe integer; minimum 0; maximum 255. |
| low | Low | Required. Safe integer; minimum 0; maximum 255. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| word | Word | Required. Safe integer. |
{
"input": {
"high": 69,
"low": 0
},
"output": {
"word": 17664
}
}Limitations and assumptions
- This supplies one checksum word; it does not sum words, fold carries, or complement a checksum.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Inspect the complete captured header and apply the relevant protocol's structural and state rules.
References
Similar or alternative tools
- UDP Checksum Negative Zero Transmit Word
Accept a computed 16-bit checksum and replace zero with 65535; return every other word unchanged.
- ICMP Identifier Sequence Word Split
Split the identifier and sequence 16-bit words into high and low octets, returning four bytes in that order.