【My Study Note】Unicast, Multicast, and Broadcast
Unicast, Multicast, and Broadcast
Unicast
Ways for one device to transmit data to another device is known as unicast. Unicast transmission is always meant for just one receiving address.
At the Ethernet level, this is done by looking at a special bit in the destination MAC address. If the least significant bit in the first octet of a destination address is set to zero, it means that the Ethernet frame is intended for only the destination address.
This means it would be sent to all devices on the collision domain, but only actually received and processed by the intended destination.
Multicast
If the least significant bit in the first octet of a destination address is set to one, it means you’re dealing with a multicast frame.
A multicast frame is similarly set to all devices on the local network signal. What’s different is that it will be accepted or discarded by each device depending on criteria aside from their own hardware MAC address.
Network interfaces can be configured to accept lists of configured multicast addresses for this sort of communication.
Broadcast
An Ethernet broadcast is sent to every single device on a LAN. This is accomplished by using a special destination known as a broadcast address.
The Ethernet broadcast address is all Fs.
e.g. FF:FF:FF:FF:FF:FF
Ethernet broadcasts are used so that devices can learn more about each other.