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Ethernet
Addresses
An address is unicast if the least significant bit of the first byte is 0. Otherwise, it is either broadcast:
- FF:FF:FF:FF:FF:FF: segment broadcast
or multicast:
Local Network Control Block (224.0.0/24)
- 01:00:5e:00:00:01 (224.0.0.1): All-Hosts
- 01:00:5e:00:00:02 (224.0.0.2): All-Routers
- (224.0.0.22): IGMP
- (224.0.0.251, ff02::fb): mDNS
- 33:33:00:01:00:02 (ff02::1:2): DHCPv6 server/relay
Locally-assigned Addresses
If the penultimately-significant bit is 1, the address is "locally assigned" (read: made up). This is used by the Linux kernel's rand_hw_addr() function, used by PPP and TAP.
See Also
- Ethernet page on the Wireshark wiki
- Ethernet is specified in the IEEE 802.3 standards