Our Focus
Making IP work!
In this issue I want to try to explain some stuff about IP – Internet Protocol – and how to make things work over IP. I will be relating to the IP converters we use, how to think about networks and how to set them up. That said, most of this relates to any ‘IP system’. Now, before you respond with ‘but it doesn’t work like that’, this is just a guide and my way of thinking about it that offers just enough understanding to get IP working. It’s not necessarily exactly how IP works but thinking about it like this enables getting things to work.
I will also be making a video on this subject with illustrations of how we set up our IP system on a network. You can find the video via our website.
IP = Internet Protocol
Firstly, the basic thing to understand about IP is that it is merely a method of transporting data from one place to another – just like a cable or a fibre optic. It really is just this – a means of sending data from one place to another. This data can be pictures, videos, a spreadsheet or control data for a camera.
IP, or Internet Protocol, is the protocol that is used to ‘wrap up’ the data you want to send so that it can be sent over an IP network. It’s a bit like sending a letter in the post. The letter could be a birthday card, a love letter or a form you’ve filled in for your bank, it doesn’t matter, as long as you put it in an envelope and write the address on the outside. The postal service doesn’t know what’s inside and it doesn’t care. The Internet Protocol, or IP, is like the envelope with the address - in the world of networks. The word ‘protocol’ is sometimes misunderstood as we use other protocols to control things. VISCA protocol, PelcoD protocol and our own Dstar protocol, for example. Internet Protocol is a way of ‘packaging’ any of these protocols, or any other data, so it can be sent over a network. Internet Protocol is not a control protocol, it’s just a method of standardising, or packaging, any data so that it can be sent from one place to another over an ‘IP network’. So, within the Internet Protocol you might send Dstar protocol commands for a camera.
There are several ways that IP can send the data. One is TCP (Transmission Control Protocol) and another is UDP. We use UDP which stands for ‘User Datagram Protocol’ and is the quickest of the network protocols. Fundamentally, it broadcasts the data to everywhere on the network to whoever wants to receive it. It just sends it out as it gets it, with no error checking and does not repeat anything. Error management is up to the originating protocol to handle, like Dstar does. UDP is the closest thing to real-time transmission.
IP Addresses
Everyone has heard of IP Addresses. These are the individual addresses given to pieces of equipment connected to a network and might look something like this; 192.168.0.241.
This is our default address for Camera No1. Camera 2 would be 192.168.0.242. But you can use any address you like.
There is another, lesser known, part of an IP address which is the Port No. You can think of this as a ‘Radio Channel’ and is sometimes shown like this; 192.168.0.241.2101. This adds Port 2101 to the address. So even if you are trying to send a message to an IP Address, if you are not using the correct Port No. – or ‘Radio Channel’ - it won’t get through. It would be like trying to call your friend John on his walkie talkie. You know his name is John and he has a walkie talkie but he’s listening on a different channel so you can’t talk to him. Also, just like a duplex radio system where you transmit on one channel and receive on a different channel, devices on an IP network can send and receive on different ports even though the IP Address remains the same. Just like John, he can listen on channel 17 and talk on channel 18 but he is still John.
Another thing about IP Addresses is that a device can have the same IP Address as another device, provided it’s on a different network or sub-net. For example, you might have a camera on your network with the address 192.168.0.241 which is the same address as another camera in another organisation’s network. Each organisation will have its own internal network which is organised by a router, which in turn is connected to the outside world. This router will have its’ own IP address and the devices on the network within the building can use the same addresses as another organisation because the routers arrange their own internal networks separate from anyone else. It is possible to set up different sub-nets within the same network but we won’t go into that in this article.
IP Settings
One thing to bear in mind is that when you are setting up your devices, usually with a downloaded application to a pc on the network, the word ‘local’ means the device you are looking at, and the word ‘remote’ means the device or devices at the other end of the connection. Obviously, this will swap around if you are looking at the camera end or the controller end. The ‘Local Port’ is the port on which the device will receive data and the ‘Remote Port’ is the port on which it will send data. So, if you have just 1 controller and 1 camera these Port Nos. will swap positions between the controller and the camera.
Below is a list of all the settings you need to get right to connect a controller to a camera on the same network.
IP Address of the controller
IP Address of the camera
Subnet mask (the same for both controller and camera)
UDP (broadcast)
Port No. to talk to the camera
Port No. to reply to the controller
At the controller end you need to set the address of the cameras it needs to control. For example, this can be set as. the ‘255’ number tells it to send to all devices on the subnet which starts with 192.168.0. … the last number can range from 001 – 254 (254 cameras) with 255 being ‘send to all’.
At the camera end you need to set the ‘Remote Host’ address and ‘Remote Port’ to something else on the network – usually the controller. We use Port 2101 to send to all cameras and Port 19301 to reply back to the controller and for the camera metadata.
The Subnet Mask tells the network which part of the IP address is the subnet address and which part is the device. I won’t go into detail but for the address above - 192.168.0.255 - the subnet mask would be 255.255.255.0. This indicates that the subnet part of the IP address is the 192.168.0 part and the device number is the ‘255’ part at the end.
You may also see ‘Gateway’ which you don’t need to worry about. This is the IP address of the router which would be used if you want to send data outside your network via the internet.
Data format
You also need to tell both the controller end and the camera end the data format you are using so that it can be encoded and decoded properly.
There are some basic things that define the data.
The physical format - RS485,232 etc.
The speed - 9,600 baud, 38,400baud etc.
The data format - how the bits and bytes are arranged and separated
The protocol - VISCA, PelcoD, Dstar etc.
The physical format of the data, eg RS232, RS485 is decided by the actual hardware. The correct chips will be fitted to convert data into data that the IP Interface can handle. Generally we would fit RS485 chips for both input and output data. You don’t need to worry about this as it’s fixed. The things you need to set are;
Data baud rate and format. For example 38,400, 8, o, 1
This is a baud rate of 38,400 bits per second, arranged in 8bit bytes, with ODD parity and 1 stop bit. We use this as it’s the same as industry standard Free-D protocol which is used for metadata for VR graphics etc. Our cameras and heads put this onto the network automatically.
There is no Flow control.
The only other thing you might need to set is a time interval which we normally set as low as possible at 1mSec.
The protocol is irrelevant to the IP network as it just sees data and ‘wraps’ this in its’ own IP protocol format.
Latency
To broadcast a message using UDP to every possible destination can take some time as there are 1000,s of routes and destinations, even on a small network, so there may be a delay, which we call latency. To reduce this latency, it’s important to give everything something to talk to. When something is connected to a network it sends an ‘I’m here’ message onto the network to the destination defined as its’ ‘Remote Host’. If this message is received, and only if it is received, the network logs the location of both devices. After that, all subsequent messages are prioritised to all the destinations that have sent and received the ‘I’m here’ message. This reduces the latency to just a few milliseconds. It is important to set the cameras’ ‘Remote Host’ to an address that is actually on the network and for this device – perhaps the controller - to be set to receive these messages. It is best to use a different ports for different directions.
So there you have it. My guide to explaining and setting up IP connectivity. Next month I might have a go at the rules of Cricket!
If you’d like to learn more about IP sub-net masking I can suggest; https://www.youtube.com/watch?v=EkNq4TrHP_U
And finally, a special offer for this month is 30% off our IP Converters and IP Stage Boxes.
https://www.br-remote.com/ip-interface-mk2-for-remote-camera-systems
For more information or to purchase one of our IP Converters of IP Stage Boxes, please email admin@br-remote.com or call us on +44 (0) 1590 622 440.