That's why the IP to MAC mapping only uses 23 bits when the multicast group part of an IP address requires 28 bits (Class D, multicast, addresses start with 1110 as the first four bits, leaving 28 of the 32 bits in an IP address for the multicast group). That means that of the 24 address bits (48 MAC address bits minus the 24 OUI bits), each person got 23 bits for addresses. Each of the two people who put up the money got to own half the addresses possible with the OUI. It cost $1000 for an OUI, which was a lot of money at the time, so the cost was split in half. The OUI for multicast was acquired from the IEEE by the creators of multicast. A MAC address does have two flag bits (the two least significant bits in the OUI), and the OUI for multicast correctly uses these bits to identify it as a universal, group MAC address. ![]() ![]() The 01-00-5E is commonly called the OUI (Organizationally Unique Identifier), which the IEEE (the group which assigns them) calls MA-L (MAC Address Block Large).
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |