Method for checking multicast LLID transmission in ethernet passive optical network

A method for checking whether a transmission is a multicast transmission or not in an Ethernet passive optical network including an Optical Line Termination (OLT) and multiple optical network units (ONUs) connected to the OLT by generating a multicast logical link ID LLID that represents multicast information, from multicast Medium Access Control (MAC) addresses in a MAC layer in one of the multiple ONUs or the OLT, so that at least one ONU from among the multiple ONUs or the OLT receives the multicast transmission, the method comprising the steps of:

• (a) increasing a quantity of bytes of a preamble assigned to the LLID and then inserting a group identifier from among the multicast MAC addresses into an LLID field in a Regenerator Section (RS) layer below the MAC layer;
• and
• (b) generating mode information that represents a multicast transmission, locating the mode information in a position adjacent to the LLID field,
• wherein, the RS layer checks whether a transmission transmitted to the ONU or the OLT is a multicast transmission or not.