What to Do When Your Customer Says, ‘I Want My (Remote) CCTV!’
Virtual Local Area Networks Suffice for Small Systems
OK, so you’ve installed the DVR, you’ve installed the software on the user’s computer, and now you need to move video. Where do we go from here? We need to answer that question with another question: How far do we need to go? If the answer is across the room or between rooms in a building/campus, then we are probably on a LAN and shouldn’t have too many problems, provided the network is set up correctly.
One thing you will need to do is ensure the DVR has a clear path through the network to the client PC. On small business or home networks, this usually isn’t a problem as they will probably only be dealing with a single subnet or group of IP addresses. This means any IP address can talk to any other IP address on that same subnet. So it should be a matter of plugging the box in and giving it an address from the proper subnet.
On larger networks, this may become an issue. In order to control traffic on a network, especially broadcast traffic (traffic that isn’t directed at a particular machine, just broadcast out to the entire network), network administrators will often use VLANs, or virtual LANs. A VLAN essentially isolates network segments using different subnets, but allows all the traffic to continue to share the same infrastructure (switches, routers, etc).
This will come into play when you install digital video equipment in a large business or campus environment. You will need to make sure the video system, and any authorized clients, has access to the same VLAN, otherwise they will not communicate.
This is more than simply plugging in correct addresses. The network infrastructure will need to be configured so that all central devices on the network know the VLAN exists, and can properly direct traffic through it. As always, work closely with the network personnel at the company before you fire anything up.
Now, what if you need to send this video over a large distance? What if your customer wants to view his Los Angeles office from New York? What about the “viewing from home” scenario? We basically have two choices at this point: the Internet or a private WAN.
Knowing the Ins and Outs of Using the Internet Via DSL or Cable
What if the customer has DSL at the office and at home, but the Internet in between? Can he or she view video from home? The definitive answer is “maybe.”
DSL, or digital subscriber line, is what the telephone companies call a “last mile” technology.
It was developed as a way to extend high-speed WAN connections out to the residence or small business over standard telephone circuits. DSL itself only exists between your house/business and the telco’s central office (CO). After that, the packets jump on one of the larger backbone circuits that power the Internet.
DSL is an excellent way to get high speed Internet access at your location. It is relatively inexpensive, and fairly robust, although it does not carry the uptime guarantees of a T-1 or similar circuit. It can, however, provide speeds similar to or even exceeding the 1.5Mbps (megabits per second) of a T-1 leased line.
DSL has one major drawback. The standard DSL packages you purchase from your local phone provider are designed to allow high-speed downloading from the Internet. That is a very important distinction. Your off-the-shelf DSL special is usually what is called ADSL, or asynchronous DSL. That means the upload and download speeds are not the same. The download speed is generally much higher than the upload.
If you are at the customer’s home where the viewing of the video will take place, this might be OK. But if you are at the location where the DVR resides, this will be a problem if the DSL upload speed is less than the download, because video streaming from the DVR has to be pushed UP to the Internet, not downloaded.
This is a problem with DSL because it is distance limited. The farther away you are from the DSLAM (DSL access multiplexer) within the telco’s CO, the lower your speeds, both up and down, will be. Even if you are close to a CO, and you get the full 1.5Mbps down or better, you still may see upload speeds of only 64kbps or 128kbps. Presently, the highest upload speed for a consumer DSL package is 768kbps, still a far cry from 1.5Mbps.
Another common consumer broadband connection is via cable modem. This is provided by the local cable-TV carrier and can be a good alternate in some cases. It can provide very high data rates, sometimes in the area of 6-8Mbps. But like DSL, there are cautions of which to be aware.
The biggest issue with cable modem broadband is the fact that it is a shared network out at the neighborhood level. You and others in the area with the same cable provider are sharing a link back to the cable-TV office. This presents another speed problem. While cable doesn’t suffer from distance limitations like DSL, it does suffer from user limitations. Basically, the more users online, the less bandwidth is available.
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