MAC Address Architecture & OUI Vendor Lookup: EUI-48, Bit Masks & Packet Analysis

First Octet Bit Layout:
Bit Position:  7   6   5   4   3   2   1   0
             ┌───┬───┬───┬───┬───┬───┬───┬───┐
             │ b7│ b6│ b5│ b4│ b3│ b2│U/L│I/G│
             └───┴───┴───┴───┴───┴───┴───┴───┘
                                       │   │
  U/L: 0 = Universal (IEEE Assigned) ──┘   │
       1 = Local (Randomized/Virtual)      │
                                           │
  I/G: 0 = Individual (Unicast) ───────────┘
       1 = Group (Multicast/Broadcast)

// Enterprise MAC Address Normalizer & OUI Extractor in TypeScript
export interface MacAnalysisResult {
  raw: string;
  normalized: string;
  isValid: boolean;
  isMulticast: boolean;
  isLocallyAdministered: boolean;
  ouiPrefix: string;
}

export function parseMacAddress(input: string): MacAnalysisResult {
  // Strip delimiters (colons, hyphens, periods, whitespace)
  const cleaned = input.trim().toLowerCase().replace(/[^a-f0-9]/g, '');

  if (cleaned.length !== 12) {
    return {
      raw: input,
      normalized: '',
      isValid: false,
      isMulticast: false,
      isLocallyAdministered: false,
      ouiPrefix: ''
    };
  }

  // Format into standard IEEE colon-delimited octets
  const octets = cleaned.match(/.{1,2}/g) || [];
  const normalized = octets.join(':');

  // Evaluate flags in the first octet
  const firstByte = parseInt(octets[0], 16);
  const isMulticast = (firstByte & 0x01) === 1;
  const isLocallyAdministered = (firstByte & 0x02) === 2;

  // Extract 24-bit OUI prefix (first 3 octets)
  const ouiPrefix = octets.slice(0, 3).join(':').toUpperCase();

  return {
    raw: input,
    normalized,
    isValid: true,
    isMulticast,
    isLocallyAdministered,
    ouiPrefix
  };
}

// Example usage:
const sample = parseMacAddress('00-1A-2B-3C-4D-5E');
console.log(`Normalized: ${sample.normalized} | OUI: ${sample.ouiPrefix} | Local: ${sample.isLocallyAdministered}`);