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Rules for Bootp Vendor Tag Entries
Last Updated: July 07, 2026
  1. Each valid vendor tag entry must contain a one-byte vendor code, a one-byte length and value of length bytes.
  2. A code can be any number from 1 to 254.
  3. Once a code is used, it cannot be repeated.
  4. The total size of vendor data must not exceed 58 bytes (1 start, 1 stop, 4 bytes for the vendor magic cookie and 58 for the vendor data information = 64 bytes). The size of each entry can be calculated by adding two to the size of the value field. The size of the value can be determined as follows:
    • String: length of string (without terminator)
    • Decimal IP Address: four bytes
    • Hex IP Address: four bytes
    • MAC Address: six bytes
    • Hex ASCII: length of string (without terminator) divided by two
  5. Value and type must be consistent with one another:
    • When type is STRING, the value must contain a string of ASCII characters.
    • When type is DECIMAL IP ADDRESS, the value must contain a valid dotted decimal IP address format (for example, 193.1.17.5).
    • When type is HEX IP ADDRESS, the value must contain a valid dotted hex IP address (for example, a8.54.ae.24).
    • When type is MAC ADDRESS, the value must contain a valid MAC address (for example, 00:30:64:05:8d:b4).
    • When type is HEX ASCII, the value must contain an even number of hexadecimal characters (for example, 0-9, A-F).