Universal and locally administrated MAC addresses are distinguished by setting the second-least
significant bit of the most significant byte of the address – known as the U/L bit. If the U/L bit is zero the
address is universally administered, if it is one the address is locally administrated.
If the least significant bit of the most significant octet is zero the network frame is meant to reach only
one receiving network device (NIC). This type of transmission is called Unicast addressing – the frame is
transmitted to all nodes within the collision domain, which usually ends at the nearest network switch or
router. Only the network device with the matching MAC address will accept the frame.
If the least significant bit of the most significant octet is one each network device will choose to accept
the frame based upon a different criteria other than a matching MAC address; maybe a configurable list of
accepted MAC addresses. This type of transmission is called Multicast addressing.
The CFSound-IV currently only supports Unicast addressing. The default MAC address is
02:01:23:45:67:89 – which configures a Unicast, Locally Administrated MAC address.
The MAC address must be configured to be unique amongst all devices on the network segment that the
display is attached to. As it is locally administrated it is the user’s responsibility to ensure that it is a
unique value.
IP Address
An Internet Protocol address (IP Address) is a numerical label assigned to each device participating in
the network that uses Internet Protocol for communication. The IP Address serves two functions; host or
network identification and location addressing. The CFSound-IV currently supports IPv4 protocol which
requires a 32-bit IP Address number.
The IP Address is a 32-bit binary number, but it is usually expressed as 4 decimal numbers, each ranging
from 0 to 255, separated by dots. Each decimal number represents a group of 8 bits (octet) of the address:
An IPv4 address (dotted-decimal notation)
192
.
168
.
1
.
200
↓
↓
↓
↓
11000000
10101000
00000001
11001000
↓
11000000 10101000 00000001 11001000
32-bits (4 x 8 bits), or 4 bytes
Devices that are not directly connected to the Internet but only use the network to communicate do not
need globally unique IP Addresses. The Internet Assigned Numbers Authority (IANA) has defined three
ranges of reserved, private IP Addresses for these devices:
IANA-reserved private IPv4 network ranges
Start
End
# of addresses
8-bit prefix
24-bit block
10.0.0.0
10.255.255.255
16,777,216
12-bit prefix
20-bit block
172.16.0.0
172.31.255.255
1,048,576
16-bit prefix
16-bit block
192.168.0.0
192.168.255.255
65,536
Private networks typically connect to the Internet through a Network Address Translation (NAT) device
such as a router. The NAT hides a large number of IP Addresses in the private network by mapping TCP and
UDP port numbers on the public network to individual addresses on the private network; the port numbers are
site specific extensions to an IP Address. This allows a large number of devices on the private network to
appear to have a single IP Address on the public Internet.