'Convert packed 128-bit IPv6 address bytes into a colon-separated ASCII
bytes representation of that address.
@param bytestring: 16 octets representing an IPv6 address.
@type bytestring: L{bytes}
@return: a dotted-quad notation IPv6 address.
@rtype: L{bytes}'

@staticmethod
def _bytesToIPv6(bytestring):

    hexString = binascii.b2a_hex(bytestring)
    return ':'.join((('%x' % (int(hexString[b:(b + 4)], 16),)).encode('ascii') for b in range(0, 32, 4)))
