10 Things Every Stagehand Should Know About Computer Networking
Posted on Monday, March 28th, 2011
Written by Richard Cadena
“I got in this business so I wouldn’t have to read.” -Doug Heffernan, TV’s “King of Queens.”
In 1965, Intel co-founder Gordon Moore predicted that computers would double in power approximately every two years. His prediction became known as Moore’s law.
Later on, Intel CEO Andy Grove coined his own law, with his tongue planted firmly in cheek, predicting that networking speed would double every 100 years. Grove was lamenting the fact that, at the time, networking speed had not kept up with computer power.
That was then. Today, computer network technology has improved to the point where we are able to transport huge amounts of data over copper, wire and fiber. That’s why we can stream videos to our laptops using Netflix and Hulu, and why new televisions can connect to the Internet. It’s also why the live event production industry is being inundated with network technology. You can hardly swing a disconnect switch by its feeder tails without hitting a network-connected console, media server or computer. If we’re going to be in this business for long, we had better get comfy with the technology.
The Ubiquitous Computer Network
The first time I ever heard the term “DMX universe” was in the early 1990s. Until then, 512 slots of DMX was plenty. Then things got more interesting. As automated lighting grew more complex and full-featured, it started chewing up more DMX slots. At the same time, lighting rigs were expanding. What was once considered a “large” lighting rig was dwarfed by the Michael Jacksons and Britney Spears rigs of the world. Then along came media servers and LEDs, and suddenly the industry realized that if we didn’t want to be running wads of DMX cables from FOH to dimmer beach or to the dimmer closet, then we had better come up with a better solution. That solution was right under our collective noses, in our homes and offices, courtesy of the computer industry, and it was the computer network. Now when you go to a show, you need only sniff the air and you’ll find it’s teeming with 802.11, 802.3, TCP/IP and Ethernet. But what does it all mean?
TCP/IP is a suite of communications protocols including transmission control protocol and Internet protocol that is commonly used for computer networking. Most entertainment networks, including the ones used with most lighting and automation consoles like Art-Net, ETCNet, StrandNet, etc., are TCP/IP-based networks.
2. Ethernet and WiFi:
Ethernet is one of the physical embodiments of TCP/IP networks and WiFi is another. These are standards that describe the infrastructure of a network, like the cable type or the transmission frequency. Ethernet and WiFi are two of the most common types of networks in the live event production industry. They are borrowed from the computer industry so that we can use the same hardware we use with our networks at home and in our offices.
3. IEEE 802.3 and 802.11:
Technically, Ethernet is a standard called IEEE 802.3. It was originally developed by Xerox, Digital Equipment Corporation (DEC) and Intel from 1973 to 1975, and it was formally standardized in 1985 by the Institute of Electrical and Electronic Engineers. WiFi is IEEE 802.11, which is the standard for wirelessly transmitting TCP/IP-based networks.
4. Ethernet, Fast Ethernet, Gigabit Ethernet:
Several different flavors of Ethernet have been developed over the years based on the speed of transmission. The earliest has a transmission rate, or “baud” rate, of 10 megabits per second (Mbps). Later on, when cabling and networking techniques were improved, another standard was developed called “Fast Ethernet,” which runs at 100 Mbps. Still later, a standard called “Gigabit Ethernet” came along, which runs at 1000 Mbps or 1 Gbps, and today we have 10 Gbps and 40 Gbps Ethernet. Someday we’ll have 100 Gbps and 1000 Gbps, or Terabit Ethernet. (Did I really just say that? Terabit per second? Wow!)
5. 8-Pin 8-Conductor (RJ45) Connectors:
These different types of Ethernet use the same connectors and similar cable. The connectors are technically 8-pin 8-conductor (8P8C) connectors but you know them as RJ45 connectors, those clear plastic connectors with the little plastic tab that breaks off at the mere thought of taking one on any touring show. I was once on a tour where the production company sent these to connect a laptop at the front of house to DL2s on stage. They lasted exactly one load-out, and then it was, “run the cable, connect to the DL.2s, gaff-tape it in place.” For that reason, manufacturers have developed “ruggedized” connectors that look like a regular 8P8C connector with an XLR outer shell and ruggedized cable, which looks much like DMX cable. Much better.
6. Cat 5, Cat 5e, Cat 6, and Beyond:
The cables are standardized according to categories. You may have heard of Cat 5 cable, which used to be the most common type of twisted pair networking cable around. Today, Cat 5 is hard to find and it has being replaced by Cat 5e and Cat 6 cable. These are different categories of cable as defined by the Telecommunications Industry Association. Cat 5 cable can be used for Fast Ethernet networks while Cat 5e and Cat 6 cable can be used for Gigabit Ethernet.
7. Collision Domains:
Networks run fastest when there is little traffic on the wires; that’s why the Internet slows down at your house when everyone in your neighborhood comes home from work and jumps online. Limiting traffic on a network helps maintain its maximum speed, and there are devices that help accomplish this feat. It’s done by physically segmenting networks with routers, switches and bridges.
8. Routers, Switches and Bridges:
A bridge is a single input, single output device that filters data on a network to reduce traffic. It does this by only passing data intended for a computer in the network as indicated by the media access control (MAC) address, which is a sort of electronic serial number programmed into each computer. A bridge divides a network in two parts; the part before the bridge and the part after the bridge. A switch also filters data according to the destination MAC address, except it is a single input, multiple output device. It only sends data to the output link on which the matching computer is located by physically connecting the input and the output port. A router also filters data on a network, except there is no physical switching. Instead, data is routed to the correct computer with software using the IP address of the destination computer.
9. IP Address:
Since you asked, an IP address is kind of like a street address on an envelope; it’s a number that helps data find its intended destination, except an IP address is usually temporary. Most computers currently use version 4 IP addressing, which is a 32-bit number, but there are so many Internet appliances today that we are quickly running out of addresses. Version 6 IP addressing uses 128 bits, and it will soon be more common than IPv4.
The more astute among you will note that mention was made of 10 things that every stagehand should know about computer networks. The last, and perhaps most important thing that every stagehand should know about computer networks is where to find more information about them. One of my favorite networking primers is Rock Solid Ethernet by Wayne Howell.
Like Doug Heffernan, a lot of us got into this industry so we wouldn’t have to read. And a lot of us have been displaced from this industry because we chose not to read much. Don’t be a Heffernan.