How IP Cameras and Systems Work: A Brief Introduction to Networks

IP cameras and IP surveillance systems work a bit differently than their legacy Analog predecessors. The good news is that we do have simplified IP systems available that do not require advanced networking knowledge to set up a closed system.

However, if you’re looking to do a more complex install, you should take a look at the video below. If you need more detail, read through this guide. 

Components of an IP Camera

The external components of an IP camera Consist of:

• Pigtail
  • RJ-45 PoE 802.3af (this will accept PoE or regular network connections)
  • 12V DC input (optional use on PoE cameras)
• Housing
  • Bracket (used for mounting, pointing, and protecting the pigtail from tampering)
  • Lens Cover
  • Sun Shield (reduces glare)

Of course, not all models are the same, but many of our models will have a similar style. Some cameras include additional inputs for RS485 (PTZ Controls), Audio, and Alarms. Most of the cameras you receive from us will be 12V DC. Some of the more power hungry PTZ Cameras will require 24V AC or PoE+ (802.3at).

The internal components mimic that of a simple computer. The Digital Signal Processor (DSP) will be laid under the CMOS image sensor or sometimes will be placed separately on the board.

Powering an IP Camera

IP cameras do need to be powered in order to work. Even the wireless IP cameras we offer will have to be connected to power. There are two ways to power our IP cameras:

• DC Adaptor (12V DC)
• PoE (802.3af/at)

Each IP camera’s pigtail will have an RJ-45 port and a female DC input. Either one of these can be used to power the camera unless it is a WiFi camera. WiFi cameras are not capable of PoE and must be powered using a 12V DC power supply.

Using PoE to Power Your IP Camera

PoE stands for Power over Ethernet. This is a specific standard IEEE 802.3af. Not all network switches conform to this standard. Most network switches will use another standard that does not inject power across the lines.

If you want to power your cameras via PoE, and will be connecting them to an external switch or injector, be sure it is a PoE switch or injector that conforms to 802.3af.

Using other PoE switches could fry your camera. Not using a PoE switch at all will not power your camera. Don't use wireless access point PoE injectors insert pics of what not to use and what to use.

Data Communications with IP Cameras

Video and audio files are compressed at the camera using the encoding method selected. Then they are sent through the network as data to a device like your NVR. The way an IP camera connects to network the most times is via a cable.

• Wired Connection
  • Once powered and configured, communicates with connected switch to send information across the network
  • Data travels through the network toward the NVR, computer, or phone getting redirected to the next device down the line until it reaches its destination
  • High-speed communications, not subject to radio interference, constant connection
• WiFi Connection
  • Using the credentials you program into the camera, it connects to a wireless radio broadcasting a specified SSID
  • Connections speeds and signal strength will fluctuate due to radio interference
  • Once the camera is connected to a WiFi signal it will be available to send data across the network to a phone, computer, or NVR
  • WiFi connections are subject to signal loss; after disconnection, you will lose your camera feed until the device reconnects and begins transmitting data

Addressing your IP Cameras

A network camera or IP camera, like any other accessible device on a network, requires an IP address to send and receive communications. Like any other device with an IP address on a network, it must be unique to that segment.

You Shouldn’t Use DHCP to Address the Cameras

Most devices that you plug into a router get assigned an available address automatically using DCHP. The address is given to the device on a lease of a specified time frame.

Once the lease is up the device will renew the lease. When this happens, or if the device is powered off, or if the device loses connection with the network in any way, it will be given another IP address.The address could be the same one you got last time, but most likely it will change.

Given that we need to point to these devices and create rules with the address, we’d much prefer these devices to keep their address, and never change. Therefore their IP address will need to be configured to be static (not changing). By default, nearly all of the IP cameras you receive from us will have a Static IP Address

By default, nearly all of the IP cameras you receive from us will have a Static IP Address of: 192.168.1.108

What is an IP Conflict?

If two or more devices on a network have the same IP address an IP conflict is created. Each device with that IP address will cease communications on that network until the conflict is resolved. Generally, this is done by removing the devices from the network, changing their IP address, and attaching them to the network again. When you are placing devices on the network be sure that you are not attaching devices with duplicate IP addresses.

Understanding Network Communications

IP cameras communicate over a network the same way every other device does. They take the data the want to send and break it up into packets of information. These packets not only contain part of the data, they contain metadata as well (data about data). In essence, they will all have the following:

1. The IP address where the packet originated
2. The IP address of its destination
3. The data itself
4. Instructions for network devices on how to pass along the data
5. Where the packet fits in reassembly
6. Error checking information

These are grouped into three sections:

1. A header that contains
   • An alert to signal that the information is being transmitted
   • Source address
   • Destination address
   • Clock information
2. The data
3. A trailer that contains the error-checking aspect

These are broken into small pieces to assist with error handling. If a packet reaches its destination and fails an error check the end-point devices will send a request to resend the information.

1. The IP camera establishes a connection with the NVR
   

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2. The IP camera breaks the compressed video into packets with a header and trailer and begins transmitting
   

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3. As the data travels through devices such as PoE switches, Routers, Etc. the header is examined and the packet pointed to the right direction. This is called a hop. Each hop will add latency to the transmission delaying the video feed.
   

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4. At the NVR the packets enter the device through the cable into the NIC
5. The information is stored in the NICs buffer
6. The network operating system reassembles the packets to usable data and pushes it into memory where the NVR takes over and sends a signal back to the camera confirming successful delivery.

 

Latency

We can assume at an enterprise level that there will be more cameras attached to the network, along with various servers, more switches, and multiple workstations. Only a few are shown above to lessen the complexity.

Latency can also be affected by the current load on a node to provide routing to multiple devices that are sending and receiving data. If the camera's data is queued to transmit after other transmissions, this will add time to the communication.

As you can see in the above image, the red arrows indicate the cameras feeds traveling through the LAN back to the NVR to be recorded. In a mesh network, the packets can take multiple routes to their destination. Here we keep it somewhat simple though and only offer a direct route.

The cameras are constantly compressing video and sending data packets back to the NVR. Once received the NVR will reassemble the packets and error check. After checking for errors the NVR will tell the camera to stop, continue sending data, or to resend the last transmission. This is yet another transmission that needs to be sent down the line back to the cameras.

Transmissions from the NVR are indicated by green arrows. This will be the constant back and forth between the cameras, as well as streaming to any remote monitor from a workstation, laptop, phone, tablet, or any other remote devices.

In this example, the PoE switches will only carry the camera communications. Therefore they have a lighter load on the network than the other switching devices. Information to and from both PoE switches with attached cameras transmits through the same network switch.

This network switch communicates with both PoE switches, the router, and in an enterprise setting other devices as well. If all specs other than power injection are the same across all routing/switching devices we find that network switch 1 is going to have longer latency times than the PoE switches.

Next in route is the Router. The Router has the heaviest communications load. Not only does it connect two branches of the network, it also connects WiFi devices and provides internet communications to the entire network. Most of the traffic will pass through the router in this example.

Network switch 2 receives a signal from the router and forwards it to the next switch in line. All devices on network switch 3 must pass through network switch 2 creating a heavy workload for it. This device also connects other devices on the network giving LAN and WAN access to these devices.

Network switch 3 connects to more than just an NVR in an enterprise setting. However, this is the last hop when communicating with the cameras. Given that there is no other switch than the one in front of it connected directly to this network switch, it has a lighter load as it's not forwarding additional communications to another switch down the line. The load may still be heavy, though.

Network communications from the NVR to a WiFi device monitoring locally will need to travel through network switch 3, network switch 2, and the router. It will take the same path for remote viewers. Although, there will be more hops as the packets will be traveling across the internet, creating a longer delay.

It does take time for a data packet to travel down a line.

It takes time for each device to analyze the header of the packet and redirect it.

If the packet is queued for forwarding, it will take some time to complete the transmissions ahead of it in the queue before it's next in line.

Albeit were measuring this time in milliseconds, but this time adds up. As you increase the number of switching devices between you and your NVR, and between the NVR and IP camera you increase the latency time between the initial sending of the data and the receiving of the data.

This is not just over a LAN. You will encounter greater latency when establishing a connection via the internet as there are more hops, that perform far greater numbers of communications than you would on a local network. So expect to have the NVR’s packets queued for transmission by your ISP when you connect to your NVR remotely.

All of this is just the time to transmit the data. Whatever device receiving it will have to process this information to display it in a usable form, but that's another topic.

What Have You Learned About IP Cameras?

IP Cameras are comprised of small printed circuit boards with the components of simple computers housed in within the cameras shell.

IP cameras do require power; either 12V DC or PoE (IEEE 802.3at/af) to power its components on.

IP cameras communicate via the network the same way other devices communicate on a network.

IP cameras should have a static IP address that is unique to the LAN.

Depending on the load and complexity of your network you may encounter long latency times (a few seconds).

Network attached IP camera systems are far more complex than PoE NVR IP Camera Systems.