ETHERNET GUIDE FOR THE SET LIGHTING TECHNICIAN
Written by: Matthew Ardine,
IATSE Local 728
ETCP Certified Entertainment Electrician & Trainer
With the advent of LED’s, media servers, and moving lights, there is potential for hundreds of DMX universes to be used on a single show. With the increase in DMX universes being used on set, a Set Lighting Technician needs to know how to spec, install, and operate an Ethernet network.
The first step in gaining a basic understanding of Ethernet is to learn a few terms:
A device that translates a single Ethernet signal to one or several DMX-512A universes.
A specialized computer that takes commands from a lighting console to output video and/or pixel mapping data to digital lights, LEDs, projectors, TVs, LED walls, and other displays & arrays.
A small chunk of information sent over the network.
LAN (local area network)
Two or more computers linked together to share files and information.
Ethernet protocols were developed to enable computers to communicate with each other and share information. The standards were developed to allow all compliant machines, regardless of manufacturer & operating system, to access the network. The IT industry did the legwork for us and we are reaping the benefits of years of research and development.
There are many applications of how Ethernet can be used in lighting a set. The main purpose is to have multiple DMX universes over one piece of cable. It has become very popular to have a WiFi tablet or phone acting as an on-set remote for the console. This allows the Lighting Console Programmer to be next to the DP or Gaffer as they create cues. In many cases, an Ethernet solution can save some money over the traditional DMX equipment. Multiple consoles can be networked together to break up the workload for the programmers. Or a backup console can be on the network in case the master console fails. We can also use Ethernet to exchange files, print to an Ethernet enabled printer, or upload content to a media server. Everyday, a new piece of Ethernet enabled lighting gear hits the market and the applications of using Ethernet on set expand.
Ethernet allows for more data and faster speeds than a DMX512A network. DMX512A runs at 250kbps. The oldest Ethernet still in use runs at 10Mbps (10,000kbps). This is known as 10Base-T. This got upgraded to 100Base-T (100 Mbps) known as Fast Ethernet. Then 1000Base-T (1000Mbps) known as Gigabit Ethernet. Then there is 10GBase-T (10,000Mbps) known as 10 Gigabit Ethernet or 10Gbe. Currently, Gigabit Ethernet is the standard because 10Gbe is currently too expensive for most users.
CABLE & CONNECTORS
There are several generations of cable made for Ethernet that are currently in use. They have a few characteristics in common. First, they all contain 4 pairs of wires that are twisted together. They also all use an 8P8C connector, often called an RJ45. Any RJ45 connector can fit into any RJ45 Ethernet port, but each connector is cable specific as to what type of cable it will fit in it. Each new generation is backwards compatible. Cables are often male on each end and need a coupler to join two together. The maximum cable length is 100 meters (328 feet).
CAT5 is the oldest cable still in use. CAT 5 does not allow for Gigabit speeds.
CAT5E cable has a thicker jacket and allows for Gigabit.
CAT6 cable has a longitudinal separator between the pairs, more twists, and a larger gauge. This allows for less crosstalk between each pair and other cables. CAT6 can be used in a 10Gbe network, but will be limited to 37 meters (121 feet).
CAT6A has better insulation and more twists, allowing for a full 100m distance for a 10Gbe network.
CAT7 adds shielding for the individual pairs and more twists.
CAT7A is a further enhancement that will allow for 40Gbe and 100Gbe, which are not written standards yet.
The current cable standard is CAT6 because of its cheaper cost and the inaccessibility of 10Gbe devices.
You can check the cable type by looking at the writing on the jacket. Some rental houses will rent out CAT5 cable. You need at least Cat5e. You should not use that in a network that needs to operate at Gigabit speeds. The 8P8C connector is not very robust. Manufactures came out with a rugged version that encapsulates the 8P8C inside of an XLR-style connector, called Ethercon. Female Ethercon connectors can still accept the normal 8P8C connector.
A patch cable is what you will use 99% of the time. However, in certain situations, you may need a crossover cable. This cable swaps the transmit and receive lines. This is used in special situations, maybe when the console is directly connected to a node. This is called an ad-hoc network where only two devices can be connected. There is also a crossover adaptor available to turn a patch cable into a crossover. When devices are capable of gigabit, no crossover cable is needed.
A special situation to take notice of is DMX over CAT5. This is employed in Litepanels, LED dimmers, and Color Kinetics among others. It is not an Ethernet signal and cannot be used with Ethernet gear. It is simply using CAT5 cable to send a normal DMX signal. These devices use CAT5 instead of DMX cable because it is cheaper and the connector is smaller.
Unlike a DMX network, Ethernet devices cannot be daisy chained. They use a “hub and spoke” topology. All nodes must be connected to a central device. In a wired Ethernet network, this central device is a switch or hub. Both have multiple ports to split the Ethernet signal. The DMX equivalent is an optosplitter, but a hub or switch passes data in both directions and does not optically isolate each port. A hub sends all packets to all devices. Unlike a hub, a switch only sends a packet to it’s intended recipient. A switch only sends packets to its intended recipients; which makes the overall network more responsive. For this reason, hubs have become obsolete and a switch is the standard device. You can have any number of switches on the network, but from a packet’s origination to destination, it shouldn’t pass through more than 7 switches. Every switch a packet passes through creates a small delay. The delays can add up and create problems.
There are many types of switches with various options. Each switch is designated by its number of ports and its speed. You can now get an 8-port gigabit switch for under $75. This inexpensive type of switch would be unmanaged.
The more expensive version is a managed switch. These have more settings for how to configure your network, but require a bit of advanced networking knowledge. There are several managed switches specifically made for the lighting industry that allow advanced options but reduce the IT knowledge needed to configure them.
There are many features that a managed switch could have, depending on the specific model. MAC address filtering can add security to your network by disabling any device that does not have its MAC address registered in the switch’s database. To add reliability, employ a switch that has Rapid Spanning Tree Protocol (RSTP), Safety Switch, MRP, or PRP. Both of these systems allow a network to be cabled in a loop or for two cables to be going between two switches. These systems will route the packets in the other direction automatically if one of the links is broken. This creates an automatic backup if a cable is broken or a switch fails. But with unmanaged switches, care must be taken to make sure that loops are not created, as this will wreak havoc on all the devices.
Power over Ethernet can simplify the cabling needed for an Ethernet device. Instead of sending data over Ethernet cable and a separate power cable, POE can do data and power over the Ethernet cable. These are two ways to get power into the cable. The first is by using a POE switch that puts power and data out all its ports. The second is by using a POE injector that uses a small inline box that will input the Ethernet cable and power cable and output both out of the Ethernet cable. On the receiving end, you need a device that can use POE. The ETCNet3 Gateway can use POE. This device takes Ethernet in and 4 DMX Universes out. Using POE with this device can be very useful if it is in the perms because a separate hot power cable is not needed. If a device does not use POE, but it is being sent POE, then harm will not be done because the power will be shut off at the switch or power injector when it realizes that the device does not use POE. The maximum length of an Ethernet cable is reduced by using POE. Refer to the manufacturer’s manual of your POE injecting device for cable length limitations.
A MAC address has several names that all mean the same thing: Ethernet Address, Hardware Address, and Physical Address. It is a unique, hardware-based identifier used to differentiate between connected users. Every device in the world that can be on a network has a unique MAC address. On a computer, the WiFi card and the Ethernet card have different MAC addresses.
An example of a MAC address is: 00:3g:21:d1:31:0b
It contains 6 pairs of hexadecimal numbers. Hexadecimal numbers are 0 through 9 then A through F. The first 3 pairs are specific to the manufacturer. For example, every device from ETC has the prefix of 00-C0-16. And the last three pairs would be different for all of the devices that they make.
Every device on the network also needs an IP address. Unlike a MAC address, the IP address will change depending on what network the device is on. In a lighting network, the IP address is handled more by the set lighting technician than the MAC address. When a console needs to connect to a node, you need to type the node’s IP address into the console to get the packets moving between the devices.
An IP address has 4 numbers (octets) separated by a dot. Each number can be between 0 and 255.
An example of an IP Address is: 10.23.288.5
To simplify the explanation for lighting control usage, we’ll say that there are 4 ranges of IP’s that can be used. They are:
10.0.0.0 through 10.255.255.255
172.16.0.0 through 172.31.255.255
192.168.0.0 through 192.168.255.255
188.8.131.52 through 184.108.40.206
Most lighting manufacturers have a recommended IP range. For example, GrandMA2 recommends 192.168.0.x, where x is a number between 1 and 254. This method allows up to 254 network devices. This is not to be confused with the number of DMX universes. A node might have 4 DMX outputs, but only one IP address. ETC recommends 10.101.x.x. In this method there are maybe more available IP’s.
There are a few special cases for IP addresses. Do not use 255 or 0 as the last number in an IP address. This is reserved as the broadcast address. If the console wants to send a packet to everyone on the network, instead of a single node, then it is going to address the packet to x.x.x.255.
The IP address 127.0.0.0 is the localhost loopback address. This is used in special cases where a packet needs to be sent to it’s own computer. An example of this is when GrandMA onPC and the GrandMA visualizer, GrandMA 3D, are used on the same computer. Usually, they are meant to be on two different computers, so the packets are addressed to each others’ IPs. But when they are on the same computer, the packets need to be addressed to 127.0.0.0 so that they are sent to the same computer.
Artnet operates in the 2.x.x.x range.
Subnet Masks distinguish between the network and host portion of an IP address. It is another 32-bit address that looks similar to an IP address. For most situations, the subnet mask, 255.0.0.0, will work best on a lighting control network. With a network using the IP range starting at 10.0.0.1 and subnet mask of 255.0.0.0, the addresses can be 10.0.0.1 to 10.255.255.255. The subnet mask 255.0.0.0 allows you to keep the first number (octet) in the IP (in this case, 10) and change the rest. A subnet mask of 255.255.0.0, allows you to keep the first two numbers and change the second two. There are more complicated subnet masks that you can use to create smaller subnetworks. This is a good idea if you are using huge amounts of data, but in most lighting control situations, this is not necessary and the subnet mask of 255.0.0.0 will work sufficiently.
After the equipment is ordered and before it arrives, a spreadsheet should be made of all network devices and their IP addresses. On this same spreadsheet, you can include the location of the node, and what DMX universes they are outputting. It also helps, to write this info on a piece of tape on the node above each port.
For a lighting control network, manually setting each IP is a good idea because it helps with trouble shooting problems. By knowing the IP of each device, you can run tests to see if a device is responding. This method of setting the IP address yourself is called setting a manual or static IP. The opposite and simpler method of automatically assigning IP’s is to use a DHCP server. DHCP is a protocol that assigns IP addresses to new devices when they join the network. DHCP is usually built into a router, switch, server, or console. In most home or lighting networks, it will be the wireless router that has DHCP turned on. On the EOS family of consoles, they also have a DHCP server built in. When a new device comes onto the network and is set up to use DHCP, it asks the device running the DHCP server to give it an address. That DHCP server looks at the IP range and gives the new device the next available IP. This all happens in the background. A recommended method is to use a combination of DHCP and static IP’s. If we were using the 10.0.0.x range of IP’s, then you could set the DHCP server to only give out addresses 100-254 (10.0.0.100 to 10.0.0.254) That would leave 1-99 for static IPs. This is a great system because it allows all of your devices that never leave the network to always retain their IP address, but at the same time, new devices can come on and automatically be set up to use the network. For example, you want your console and DMX nodes to always keep their IPs, but different laptops and iphones are always coming onto the network and want their IP’s set automatically.
WiFi isn’t reliable enough to depend on for show critical applications. WiFi should only be used in special cases that don’t need a solid connection. Examples of this are using a laptop, tablet, or phone as a remote to the console. In these cases, the console is hard wired to everything and if the remote’s connection goes down then DMX will still be output from the console or nodes. Wireless DMX is a better solution for applications where a wireless control signal is necessary. But WiFi can still be very useful on a lighting control network.
To get started with WiFi, you need a wireless access point (WAP). Most households have a WAP/Router combo device called a wireless router. These can speak to a device on the network that has a wireless card built into it. If the device does not have a wireless card built in, then a wireless bridge can be employed to act as a wireless converter. It would go on the receiving end, to allow a wired only device to receive wireless. If you do need a wireless Ethernet signal to be rock solid, then there are devices called wireless bridges that can give a long range single point to single point connection. It will not work as a WAP, it only communicates wirelessly with it’s corresponding receiver. These are not the $30 bridges you see at your local shop, but >$1000 devices. There are companies you can hire to install and rent one of these systems.
A third wireless device is a wireless range extender, also called a signal booster. If the wireless signal is not reaching part of the set, then this device can go halfway between the WAP and wireless receiving device to boost the signal. This will lower performance and there is limited compatibility to work with the various WAPs. A better solution is to use a WAP system where you can hardwire in a bunch of WAP’s and they all act as one wireless network. A popular one in the film industry is the Ubiquiti Unifi system.
There are several different types of WiFi, with WiFi speeds increasing as time moves along. “b” is 11mbps and is barely used now because of its slow speed. “g” is 54 mbps and still popular. The current defact standard is “ac”. It is capable of 87 to 6,928 mbps, depending on what type of “ac” you use. Wifi 6 is also on the rise and will replace AC in the upcoming years because it can manage a large number of devices all connected at once.
WiFi operates on the 2.4Ghz range, which is a crowded area of the spectrum due to multiple types of electronics using it. AC can also use the 5.0Ghz range. When they use 2.4Ghz and 5.0Ghz simultaneously, it is called dual band. On the 5.0 range, there is not as much interference because there is a much wider area to be used and not as many electronics use this part of the spectrum. Dual Band WAPs employ MIMO, which uses multiple antennas to transmit on multiple streams. So a Dual Band WAP can be transmitting multiple streams at one time to get the highest speed available, 600 Mbps.
Within each spectrum range of 2.4Ghz and 5.0Ghz, there are subdivisions called channels. When setting up your WAP, you can have it automatically pick the channel to transmit on or you can run a test, see what channels are open, and manually set your WAP to transmit in that open area of the spectrum. On the 2.4Ghz range, in the USA, there are 13 channels available, labeled 1 through 13. Using a free DOS program, Wireless Net Console, you can scan the area to see what nearby WiFi networks are using as their transmitting channel. In most situations, each channel is 20Mhz wide, but each channel is only spaced 5Mhz apart. This creates overlap between channels. So you are actually transmitting on the two channels below and above. For example, if you have channel 7 selected, then you will be transmitting on channels 5 through 9. On some “n” and “ac” models, you can transmit using a 40mhz width, which would use nine of the 13 available channels. For example, if you are using 40mhz width and on channel 7, you would be transmitting on channels 3 through 11. So even though you might be creating a stronger signal, there is more chance of interference. The 5.0 range has a much wider spectrum, there are 21 channels and they are spaced 20Mhz apart.
Ethernet over copper cabling can go up to 100 meters (328 feet). Beyond that, you can go into a switch and go another 100 meters. But you are slowing the signal down each time you go into a switch and introducing more potential failure points. A better method of long distance Ethernet, is to convert to fiber then convert back to copper on the far end. On either end, you would be use a media converter to go to and from fiber. Some switches have fiber port and multiple copper ports, so it is a media converter and switch in one. Some consoles, such as the PRG V676, have a fiber port on the console, so no media converter is needed. TMB makes a Proplex IQ node that can take fiber directly in and convert it into 8 universes of DMX.
There are many different types of fiber cable and connectors. You need to make sure the cable and connector are meant for the switch or media converter. The IT world has many different fiber cables and connectors. Most of them are not rugged enough for a temporary lighting application. For the lighting industry, there are no standards yet. PRG has their Series 400 system that can use fiber. It runs on 100BaseFX, so it is not Gigabit. The max distance of the cable is 1.2 miles. It uses multimode cable with a Lemo connector. TMB has a Proplex series of fiber products. It also uses multimode but with LC connectors inside a Neutrik Opticon connector. The PRG and Proplex systems are not compatible. To use PRG cable, you need to use PRG fiber switches and vice versa.
There are three methods that one device can send a packet to another device; unicast, multicast, and broadcast. Unicast is when a packet is sent from one device to just one other device. The switch knows which IP address is on each port and only sends it out that port. Multicast is when one devices sends a packet to a few devices on the network. Finally, broadcast is when a device sends a packet to everyone on the network. Broadcasting is a bandwidth hog and will slow down a network. Some managed switches will disable a device that is broadcasting because they are creating a “broadcast storm,” which is similar to a hacker’s attack. If you are using a managed switch, log into the settings and disable the “Stop Broadcast Storm” feature. In most cases the console wants to broadcast the DMX packets to everyone on the network, and it will be stopped if the switch is disabling a broadcast storm.
Ethernet lighting protocols can be thought of as languages. Every person speaks one language and some speak many languages. A console capable of Ethernet can use at least one protocol, most of the times, many. An Ethernet to DMX converter node can use one or many protocols. A set lighting technician just needs to make sure that the console and node are capable of using the same protocol and that each device is set up to speak the same protocol.
There are many lighting protocols, none of which are compatible, but many devices are capable of using several of them. A GrandMA’s native protocol is MANet or MANet2. It will use that protocol to speak to other GrandMA devices on the network, such as a NPU (their version of a Ethernet to DMX node), another GrandMA console, or MA3d. But the GrandMA, at the same time - and on the same network- can be speaking sACN, Artnet, ETCNet2, Pathport, Shownet, KiNet1, and CITP to other devices that are listening to one of those specific protocols.
Most of the protocols are manufacturer specific, but there are two public, royalty free protocols. Artnet was made by Artistic License and any manufacturer can use Artnet in their product for free. It became widely adopted because of this. It has several rules that need to be followed for it to work. The universe addressing can be very confusing. It starts at Universe 0 and there are several schemes of how to display an Artnet universe that we will not get into.
The other royalty free protocol is sACN. It was committee created by ESTA, a group of manufactures and end users. On a properly configured network, it can have over 2000 universes running simultaneously. sACN is easier to setup than Artnet because of its simplified universe addressing. Because of this sACN is now the defacto standard in the film/TV world.
Using Ethernet with set lighting may seem like it is only needed for really large shows that use many universes, but by understanding what is available and how to use it, you can save some money, be more efficient, and deliver a new look. Using one inexpensive Ethernet cable can save money over many lines of DMX. Attaching a WAP to a console will give a rigger the option to be channel checking using their phone in the middle of the set. Ethernet devices can save time by allowing you to have any universe available wherever there is a node, instead of having to run a new DMX cable back to the board. Having multiple programmers running two consoles in multiuser mode doubles the productivity when it is too much workload for one programmer. With some new lights and other devices being able to take Ethernet directly in, you can save money on DMX distributing equipment. Ethernet can be a very powerful tool for the set lighting department.