Description
Split the 16-bit tag-control value into the top three priority bits, the next drop-eligibility bit, and the low 12-bit VLAN identifier.
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.
Split the 16-bit tag-control value into the top three priority bits, the next drop-eligibility bit, and the low 12-bit VLAN identifier.
When to use this tool
Use Network: Vlan Priority Drop Eligible Bit Fields when you need to decode or encode one explicit packet field.
How to use the tool and how it works
- Enter tagControlInformation. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read result. Expand result to inspect the returned fields.
Split the 16-bit tag-control value into the top three priority bits, the next drop-eligibility bit, and the low 12-bit VLAN identifier.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| tagControlInformation | Tag Control Information | Required. Safe integer. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| result | Result | Required. Object. |
| result.priority | Priority | Calculated result member: number. |
| result.dropEligible | Drop Eligible | Calculated result member: boolean. |
| result.vlanId | Vlan Id | Calculated result member: number. |
{
"input": {
"tagControlInformation": 45057
},
"output": {
"result": {
"priority": 5,
"dropEligible": true,
"vlanId": 1
}
}
}Limitations and assumptions
- A field extraction does not establish whether a VLAN identifier is usable or the frame is valid.
- Outputs are nested inside result. 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
- Ethernet Vlan Priority Drop Bits
Extract the top three TCI bits as priority, bit 12 as dropEligible, and the low 12 bits as vlanId.
- Network: Ethernet Mac Group Local Bits
Decode bit zero of firstOctet as groupAddress and bit one as locallyAdministered.