중요한 것은 빨간색....첫 바이트의 마지막 비트가 1이면 결국 멀티캐스트라는 얘기..
Multicast Ethernet MACEthernet
Ethernet frames with a value of 1 in the least-significant bit of the first octet[Note 2] of the destination address are treated as multicast frames and are flooded to all points on the network. While frames with ones in all bits of the destination address (
FF:FF:FF:FF:FF:FF) are sometimes referred to as broadcasts, Ethernet network equipment generally does not distinguish between multicast and broadcast frames. Modern Ethernet controllers filter received packets to reduce CPU load, by looking up the hash of a multicast destination address in a table, initialized by software, which controls whether a multicast packet is dropped or fully received.
Some well known Ethernet multicast addresses[9] Ethernet multicast address Type Field Usage 01-00-0C-CC-CC-CC 0x0802 CDP (Cisco Discovery Protocol), VTP (VLAN Trunking Protocol) 01-00-0C-CC-CC-CD 0x0802 Cisco Shared Spanning Tree Protocol Address 01-80-C2-00-00-00 0x0802 Spanning Tree Protocol (for bridges) IEEE 802.1D 01-80-C2-00-00-08 0x0802 Spanning Tree Protocol (for provider bridges) IEEE 802.1AD 01-80-C2-00-00-02 0x0809 Ethernet OAM Protocol IEEE 802.3ah 01-00-5E-xx-xx-xx 0x0800 IPv4 Multicast (RFC 1112) 33-33-xx-xx-xx-xx 0x86DD IPv6 Multicast (RFC 2464)
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