By Scott Penno.
It wasn’t that long ago that deploying a CCTV system involved a number of cameras, a roll of co-ax and a Digital Video Recorder (DVR). If an access control system was required, this was a stand-alone system that used a twisted pair for the card reader and door strike. Any integration between the two systems was extremely limited.
Today’s security systems have evolved dramatically to offer far greater functionality, and they are truly integrated. This integration not only connects the different elements of a security system, but now encompasses other systems as well. An example of this is the integration of an access control system with the payroll and human resources department to record time and attendance information.
The drivers for this integration or convergence are twofold. The first has been the advances in technology that have enabled these systems to move from stand-alone to fully-integrated systems. Of particular importance, has been the standardisation of the digitisation, encapsulation and transmission of information. The second driver has been the demand from customers for platforms that deliver greater functionality, improved efficiency, or both.
The deployment of a security system in a retail environment may be seen as an expense associated with loss prevention. Today, that system can also be used for tracking customer movement through the store and identifying traffic hot spots. This increased functionality of the security system can be used by sales and marketing to better position product so as to maximise its exposure and saleability.
As information from access control, CCTV, building management systems (BMS) and other associated platforms has moved from analogue to digital, this information can now be easily transported by means of modern communication systems. These communication systems can include local networks where Category 5, 6 or 7 unshielded twisted pair (UTP) is commonly used or, where distance is a limiting factor, fibre. Wireless technology is also becoming increasingly popular for temporary installations, or where deployment of copper or fibre infrastructure is either impractical or cost-prohibitive.
The one thing each of these physical mediums has in common, is that they are used to deliver connectivity between devices or components of an integrated system. These devices can include cameras, encoders, card readers, access control panels, servers, storage and workstations, to name a few. The protocol or standard that enables all of these devices to communicate with each other, regardless of vendor or physical media, is the Internet Protocol, or IP.
IP (often referred to as TCP/IP) is a suite of different protocols that are used to interconnect devices within a network. While IP may be seen by many as a black art, exclusively for techno-geeks, it has become necessary for PBX technicians and security installers to have a greater understanding of these protocols as the convergence of voice communications and physical security becomes more common. This understanding is not just needed for IP issues, but also for the underlying physical media, as its application in an IP network may be quite different to that of an analogue installation.
Installers of security technology need to ensure that they have a thorough understanding of networking, or they need to partner with an organisation that has this capability. Installers that lack this capability will face significant challenges moving forward, and this is likely to have a detrimental impact on their business.
The good news is that while there are plenty of individuals and organisations that profit from making networking out to be a black art that is complex and difficult, the reality is that, with a basic understanding of how networks work, it’s not that hard.
Within the IP protocol suite, there are two primary protocols used: The Transmission Control Protocol, or TCP, and User Datagram Protocol, or UDP. TCP is similar to a telephone conversation when a call is established and information is transmitted and acknowledged. The call ends when there is no further information to be transmitted. If information is lost, an acknowledgement is not received, so the information is re-sent. UDP is more akin to a letter, sent by post, when the information is encapsulated and sent across the network and, if all goes well, the information will arrive at its intended destination. But there are no guarantees.
TCP is ideal for the transmission of lots of information when the accuracy of the information is important. Examples of applications that use TCP include web traffic (using the HTTP protocol) and email (using the SMTP protocol). UDP is ideal for the transmission of real-time information, such as voice (using the SIP protocol) and video (using protocols like RTP). The primary reason for using UDP over TCP for real-time transmission is that, if information is lost, there is little point in asking for it to be re-transmitted as it is no longer relevant. And with a well-designed network using equipment from a reputable networking vendor, the probability of errors is extremely low.
In order to design an IP network for a security system or solution, there are many questions that first need to be asked:
- What applications (CCTV, access control, IP intercom, BMS, VoIP) will operate across the network?
- Do the applications use unicast or multicast for transmission of information across the network?
- If CCTV images are to be transmitted, how many cameras will be used and at what frame rates and resolution?
- Do the endpoints require POE (802.3af) or POE+ (802.3at) and, if so, what POE class are the devices?
- What speed do each of the endpoints connect at?
- Is this a new installation, or an upgrade or extension of an existing system, and what physical media exists or have been proposed?
- What level of redundancy (interface, link, power, device, site) is required from the network?
While the last item on this list would be considered by many as mandatory, in many instances, little consideration is given to redundancy or, where it is considered, the additional expense is seen as unjustifiable. At the opposite end of the spectrum, there are installations where redundancy is considered, but each type of redundancy is considered in isolation. A good example of this is where a redundant power supply for a switch or server is purchased, but both power supplies are connected to the same power board and the same power circuit. In this instance, the only failure that redundancy is being provided for, is the power supply failure where a greater level of redundancy could have been accomplished through a couple of relatively minor, installation changes.
In today’s world of converged networking, where it is possible for a single network to be deployed to support all applications, the existence of disparate networks should be few and far between. However, the reality couldn’t be further from this. While technologically, it is possible for all applications to exist on a single network, challenges as to responsibility and Service Level Agreements (SLA) often arise. For example, as an installer of a security system over a customer’s IP network, how am I to deliver a service level agreement when I have no control over the underlying network that is used to interconnect that system? And while I may have challenges delivering an SLA, in many cases, the network administrator is not keen to have large amounts of video traffic consuming bandwidth on his (or her) network. For these reasons, it is not uncommon to have separate IT, voice and security networks.
In the second part of this article, further discussion about dimensioning networks for security applications, and the technologies that you’re likely to encounter, will be addressed.
Scott Penno has a Bachelor of Communication Engineering and an MBA in IT Management and he has been working in the Australian communications industry for nearly 20 years. Scott is currently the Country Manager for Allied Telesis – a leading vendor of wired and wireless technology for businesses across Australia and the globe.
