4.3 Ethernet MAC Address

Question 1

UNICAST

Answer 1

A unicast MAC address is the unique address that is used when a frame is sent from a single transmitting device to a single destination device.

Question 2

ARP

Answer 2

The process that a source host uses to determine the destination MAC address associated with an IPv4 address is known as Address Resolution Protocol (ARP).

Question 3

ND

Answer 3

The process that a source host uses to determine the destination MAC address associated with an IPv6 address is known as Neighbor Discovery (ND).

Question 4

BROADCAST

Answer 4

An Ethernet broadcast frame is received and processed by every device on the Ethernet LAN. The features of an Ethernet broadcast are as follows:

It has a destination MAC address of FF-FF-FF-FF-FF-FF in hexadecimal (48 ones in binary).
It is flooded out all Ethernet switch ports except the incoming port.
It is not forwarded by a router.

If the encapsulated data is an IPv4 broadcast packet, this means the packet contains a destination IPv4 address that has all ones (1s) in the host portion.
This numbering in the address means that all hosts on that local network (broadcast domain) will receive and process the packet.

Question 5

MULTICAST

Answer 5

An Ethernet multicast frame is received and processed by a group of devices on the Ethernet LAN that belong to the same multicast group. The features of an Ethernet multicast are as follows:

There is a destination MAC address of 01-00-5E when the encapsulated data is an IPv4 multicast packet and a
destination MAC address of 33-33 when the encapsulated data is an IPv6 multicast packet.
There are other reserved multicast destination MAC addresses for when the encapsulated data is not IP, such
as Spanning Tree Protocol (STP) and Link Layer Discovery Protocol (LLDP).
It is flooded out all Ethernet switch ports except the incoming port, unless the switch is configured for
multicast snooping.
It is not forwarded by a router, unless the router is configured to route multicast packets.

If the encapsulated data is an IP multicast packet, the devices that belong to a multicast group are assigned a
multicast group IP address.
The range of IPv4 multicast addresses is 224.0.0.0 to 239.255.255.255.
The range of IPv6 multicast addresses begins with ff00::/8.
Because multicast addresses represent a group of addresses (sometimes called a host group), they can only be used as the destination of a packet.
The source will always be a unicast address.

As with the unicast and broadcast addresses, the multicast IP address requires a corresponding multicast MAC address to deliver frames on a local network.
The multicast MAC address is associated with, and uses addressing information from, the IPv4 or IPv6 multicast address.