Description
Extract the top three TCI bits as priority, bit 12 as dropEligible, and the low 12 bits as vlanId.
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.
Extract the top three TCI bits as priority, bit 12 as dropEligible, and the low 12 bits as vlanId.
When to use this tool
Use Ethernet Vlan Priority Drop Bits when you need to decode or encode one explicit packet field.
How to use the tool and how it works
- Enter tci. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read priority, dropEligible, vlanId. Inspect dropEligible before interpreting the associated values.
Extract the top three TCI bits as priority, bit 12 as dropEligible, and the low 12 bits as vlanId.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| tci | Tci | Required. Safe integer; minimum 0; maximum 65535. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| priority | Priority | Required. Safe integer. |
| dropEligible | Drop Eligible | Required. Boolean. |
| vlanId | Vlan Id | Required. Safe integer. |
{
"input": {
"tci": 45156
},
"output": {
"priority": 5,
"dropEligible": true,
"vlanId": 100
}
}Limitations and assumptions
- Field extraction does not validate VLAN membership or reserved identifier use.
- 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
- Network: Vlan Priority Drop Eligible Bit 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.
- Network: Ethernet Mac Group Local Bits
Decode bit zero of firstOctet as groupAddress and bit one as locallyAdministered.