OK so what type of network is right for your application? By definition networks connect multiple devices through the use of IP for the purpose of sharing data & resources. These networks are broken down into several categories that explain where one device is in relation to another:
- PAN: Personal Area Network
- LAN: Local Area Network
- MAN: Metropolitan Area Network
- WAN: Wide Area Network
The Personal Area Network (PAN) is a new type of network that describes two or more devices that are located on your person and normally connect to one another via bluetooth. A perfect example of a PAN is a cell phone connecting to a bluetooth headset or mobile computer connecting to a portable bluetooth thermal printer. Today this type of network has no practical application in IP video surveillance but it will be interesting to see how covert surveillance starts using this in the future. Theoretically we could see a bluetooth enabled covert IP camera connecting to a wearable Network Video Recorder (NVR) the size of a deck of cards via bluetooth.
Local Area Networks (LAN) are created by a group of devices in close proximity to one another and are normally located inside the same building or structure. A LAN can be as simple as two computers connected to a single switch via CAT5 cable or 100s of cameras connected to a NVR and storage array via a group of distributed switches.
Distributed LAN in multi-story building with multiple IP Video Cameras, NVR and Monitor
Where are LANs installed:
- Office Buildings
Metropolitan Area Networks (MANs) are high speed private networks which are created by one or more dedicated point to point links between multiple locations. Each location normally has its own LAN and some level of routing will have to be done between the MAN and disparate LANs so that the two networks can communicate and share information. MANs can be created via the use of a public switched network, private fiber network or one or more point to point wireless links. As an example lets take a large University with a campus spanning several square miles and multiple buildings that wants a centrally managed IP Video Surveillance network. Well a MAN would be set in place to connect each of the buildings across the campus to a central location where the NVR and storage array are installed. The high speed of the MAN will allow the IP video to be quickly transported to the central location and recorded as if the remote cameras were on the same LAN as the NVR. If that does not make sense here is a diagram...
Multi-building ip video surveillance network connected via a MAN
As you can probably guess the Wide Area Network (WAN) connects two or more LANs that can be located large distances from one another, even across the globe. A WAN can be your Internet connection or it can be a "private" point to point (no internet) frame relay, managed layer 2 or MPLS connection you get from your internet service provider (ISP). Traditionally WANs are public switched circuits like DSL, Cable, T1s, T3s and OC3 to OC192.
- T1: 1.5Mbps
- T3/DS3: 45Mbps
- OC3 (Optical Carrier 3): 155Mbps
- OC12: 622Mbps
- OC48: 2.488Gbps
- OC192: 9.6Gbps
These are still the most prevalent WAN connections but the problem is they become very expensive very fast and when dealing with video surveillance we all know that bandwidth is our major concern. Well, today ISPs are combining MANs and WANs to create Metro Ethernet offerings that provide you with a high speed Ethernet handoff that plugs directly into your firewall or layer 3 switch instead of a router which means a much lower monthly costs and MUCH lower hardware costs.