Art-Net; Sacn; Kinet - PRG MBOX User Manual

Standard Control Protocols

Art-Net

Art-Net packets can be fully broadcast (i.e., not restricted to a particular subnet) which makes a device's subnet
inconsequential. Some Art-Net devices use full-broadcast to transmit their data, potentially flooding the network with
data.
To reduce overhead, most Art-Net devices use a subnet mask of 255.0.0.0 and generally use either 002 or 010 as
the first octet in their IP address. This places these devices into a specific subnet and they only talk to other Art-Net
devices on the same subnet. Art-Net data would be sent to the subnet broadcast IP address - either 2.255.255.255 or
10.255.255.255. While this cuts down on some bandwidth usage vs. a full broadcast, it should be noted that subnet
broadcasts still aren't the most efficient use of bandwidth.
For the best efficiency possible, Art-Net can be unicast from device to device. This cuts down on overhead, but means
that the IP address for each device must be known in advance and the precise destination for every piece of data must
be specified. This can make the hardware configuration and software setup more complex. Additionally, the device to
be unicast to must still be on the same subnet as an interface on the Mbox computer, otherwise the packets won't be
received at all.

sACN

sACN packets are typically multicast, which sidesteps the restrictions of subnets and subnet masks, meaning that any
interface can send or receive data for any multicast group it joins. Of course, the interface must still be on the correct
physical network for the multicast group. Joining a multicast group is most important when receiving data. Switches
can monitor multicast data on the network, and then filter out data that a connected interface has not elected to receive
(i.e. for a multicast group the interface has not joined).
Any interface on the computer can be used for multicast, but as noted earlier, the interface has to be specifically
identified and registered as a member of the appropriate multicast group. sACN uses predetermined multicast groups,
one for each sACN universe, with each group having a preset IP address. Without registering as a member of all of the
necessary multicast groups (for transmitting or receiving), Mbox will not be able to send or receive sACN data. For the
purposes of receiving multicast data, it is possible to have all the interfaces on a computer join a multicast group, so that
the data is received no matter what interface it arrives on. But for the purposes of outputting multicast data, only one
interface should join the group.
sACN does allow for broadcast or unicast but this functionality is not widely used.

KiNET

KiNET is intended to be unicast only. Therefore all packets are addressed to specific IP addresses. This is efficient,
but as with Art-Net unicast, the user must know all of the IP addresses of the connected devices that they want to
communicate with in advance. And as always, the Mbox computer must still have a interface that is on the same
physical network and subnet as the receiving device.
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