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As a technician involved in the installation of video surveillance, access control, burglar alarms or other security systems, you've certainly heard about Internet Protocol (a.k.a. "IP"). However, how often do you really need to know IP for your everyday job? That is an important question to consider as more systems (and jobs) are moving to IP.
Dr. Bob Banerjee, Bosch's IP video products marketing manager, is quick to point out that many security technicians already know IP; they just have varying levels of knowledge. "Most DVRs are already on the network," notes Banerjee. "This means that the installer has already set up a DVR with an IP address, with the right gateway and subnet mask. It also means that the technician has managed to install some viewing software on a PC, which is also on a network, so that it can see the DVR."
"A lot of times the technicians have different roles," notes Tim Holloway, VP Technology, Security Solutions for Anixter. "There are people who program the systems; and I'd say that for anyone programming systems, some IP knowledge is going to be critical to their job function."
However, even for technicians who aren't programming systems, IP could still be a factor. As more systems move toward IP, says Holloway, these systems will also be moving toward unshielded twisted pair (UTP) for the cables. This means that structured cabling standards (such as EIA/TIA 568) which currently apply to computer network cabling could be required knowledge for more and more security systems. As such, let's take a look at some of the basics of IP.
IP PACKETS
The entire reason an IP network exists is to transfer "packets" (or datagrams) of data from one place to another. Whether it's video, audio, e-mail, or any other data that needs to be sent, IP breaks it down into small, manageable packets to be sent over the network. Thousands (or even millions) of packets can comprise a data file that needs to be sent over the network, so each packet plays its own small but unique part. Each IP packet contains a variety of information, including its source IP address, destination IP address, payload (its share of the data file), error checking (to make sure none of the bits were corrupted during transmission, and if they were, to have the packet re-sent), and other information. Also, the delivery of an IP packet is not necessarily guaranteed (depends on the protocols used).
ROUTER
A "router" is essentially a computer dedicated to routing and forwarding packets from one network to another network. A router can connect networks of different types, and it can determine the best path to send the packets.
Another networking device is a "bridge," which is similar to a router except that it must connect networks of the same type, and it doesn't have a routing table to determine the best path for a packet.
SWITCH
A "switch" is a multiport bridging device which connects together the different devices on the same Local Area Network (LAN). A switch repeats and forwards a packet only to the network segment where its final destination device is located, which makes for more efficient network trafficking.
A "hub" is similar to a switch, but it is an older technology, less efficient, and going the way of the dinosaur (extinction). A hub forwards packets to all available network segments instead of just the final destination. This causes the network to be slower (unneeded packets slow down traffic on network segments where they have no business). Thankfully, switches are a big improvement and can be thought of as "intelligent hubs"—more efficient and more secure.
RESOURCES
When it comes to the structured cabling requirements for IP networks and other systems, there are a variety of resources available. Tom Lienhard, partner and vice president of sales for Artery Lock Technology Group, says he always carries the "Audio/Video Cable Installer's Pocket Reference" (written by Stephen H. Lampen) when he's in the field. "It is a terrific resource," he says.
Also, Anixter has many resources available. They have an IP Surveillance Guide for migrating from analog to IP video. The guide is available at: www.anixter.com/ipsurveillanceguide.
You can learn more about Anixter University and their short courses at: www.anixter.com/AXECOM/US.NSF/ProductsTechnology/SolutionsAnixterUniversityOverview.
author: by Greg McConnell