The Basics of Networking.

Networks are used within a theatre and performance situation for a variety of reasons such as lighting control and computer to computer communication. This document outlines the basics of addressing a device to communicate with other equipment in TFTS.

MAC Address.

Every device that can access, or can be accessed on, a network will have a unique identifier, known as a MAC (Media Access Control) address. MAC addresses are assigned to each device by the manufacturer and cannot be changed. A MAC address is made up of six octets, or pairs of characters. The first three character pairs indicate who the manufacturer was and are assigned to each manufacturer by the IEEE (Institute of Electrical and Electronics Engineers). The manufacturer will then assign the last three octets to the individual device, here is an example:

B8-CA-3A-8C-62-96

B8-CA-3A tells us that it is a machine manufactured by Dell Technologies, and 8C-62-96 is unique to the specific machine.

IP Address

The IP (Internet Protocol) address is the series of numbers we use to identify and communicate with a single device on our network, unlike the MAC address it can be changed as required. It is made up of four binary digits? octets and looks like this:

1.2.3.1

Each of the octets can be assigned to any number between 0 and 255.
0 and 255 have special functions so addresses are normally formed of octets between 1 and 254.

The four octets of the IP address can be used to help us identify certain characteristics of the device and if necessary, restrict which devices can communicate.

The first two octets are the network identifiers. In TFTS we use the network identifier 1.2.x.x for our stand-alone networkable equipment, this is separate to the university-wide networking infrastructure.

The last two octets are used to define the individual device. In the department we use the third octet to define the type of device, as indicated in the table below, this helps to identify the locations of problems quicker within large systems.

x.x.1.x	Wireless Router
x.x.2.x	Lighting Console
x.x.3.x	LumiNode2
x.x.4.x	Pixelite 4 mk2
x.x.5.x	Laptop/PC/Phone/iPad
x.x.6.x	Sound
x.x.7.x	Other

The final octet is the devices identifying number that is unique to that device. This can range between 1 and 254.

1 . 2 . 3 . 2

Note; avoid using 169 as the first octet as this is reserved for when a device cannot find an IP address.

Subnet Mask

The subnet mask takes the same form as the IP address with four octets. Subnet masks allow devices to only communicate with the devices they need to. Subnet values are usually made up of 0s, 255s or a combination of the two.

255.255.255.255

255.255.0.0

0.0.0.0

When an octet is set to 255 the device will only communicate with devices that have the same value in their corresponding octet.

When an octet it is set to 0 the device will communicate with devices that have any value between 1 and 254 in the corresponding octet.

Therefore, a device with 255.255.255.255 as its subnet mask will only talk to itself.
A device with 0.0.0.0 as its subnet mask will communicate with any device.

We recommend that devices are set with a subnet mask of 255.255.0.0 so that they will talk to any devices whose IP addresses match in the first two octets, ie. are a part of the TFTS network.

Default Gateway

The default gateway is the IP address where data is sent when a corresponding IP address for communication can not be found. In most cases this will be a wireless router that is bridging the gap between the LAN (local area network) and the WLAN (wireless local area network)

DHCP & Static IP

There are a number of network-addressing protocols. DHCP and Static IP are two such protocols.

DHCP (Dynamic Host Configuration Protocol) works by having a device on your network which is elected as the DHCP server. When a new device connects to the network the server allocates it an IP address and Subnet mask along with a lease. The lease is the amount of time for which the device has been allocated those details. When half of the allotted lease time has passed, the device will attempt to contact the DHCP server to renew its lease. If the time of the lease runs out, the server can then allocate those details to a different device. In large networking situations, this is ideal as details do not have to be manually entered for each device and making changes that are network wide are substantially quicker.

Static IP is set by the user, you define on each device the IP, Subnet Mask and Default Gateway. This will not change unless you manually change it.

In the department, we use Static IP as it is more practical, despite the more labour-intensive set up, it allows us to ensure that each device stays on the same IP address. Which allows for easier device recognition, making set up and troubleshooting easier.

Network Switches

Network switches are a central hub that have multiple ethernet sockets. In TFTS we have unmanaged switches, meaning that the switch is working at a junction. When data arrives at the switch, it simply copies it and sends it to all devices that are attached.

Example set up