function parseipNotation (note) {
  var pos = note.lastIndexOf('/')
  var str = pos !== -1
    ? note.substring(0, pos)
    : note

  if (!isip(str)) {
    throw new TypeError('invalid IP address: ' + str)
  }

  var ip = parseip(str)

  if (pos === -1 && ip.kind() === 'ipv6' && ip.isIPv4MappedAddress()) {
    // Store as IPv4
    ip = ip.toIPv4Address()
  }

  var max = ip.kind() === 'ipv6'
    ? 128
    : 32

  var range = pos !== -1
    ? note.substring(pos + 1, note.length)
    : null

  if (range === null) {
    range = max
  } else if (DIGIT_REGEXP.test(range)) {
    range = parseInt(range, 10)
  } else if (ip.kind() === 'ipv4' && isip(range)) {
    range = parseNetmask(range)
  } else {
    range = null
  }

  if (range <= 0 || range > max) {
    throw new TypeError('invalid range on address: ' + note)
  }

  return [ip, range]
}
Parse IP notation string into range subnet.

@param {String} note
@private