Virtual local area networks (VLANs)

When a network video system is designed, there is often a desire to keep the network separate from other networks, both for security as well as performance reasons. At first glance, the obvious choice would be to build a separate network. While the design would be simplified, the cost of purchasing, installing and maintaining the network would often be higher than using a technology called virtual local area network (VLAN).

VLAN is a technology for virtually segmenting networks, a functionality that is supported by most network switches. It can be achieved by dividing network users into logical groups. Only users in a specific group are capable of exchanging data or accessing certain resources on the network. If a network video system is segmented into a VLAN, only the servers located on that VLAN can access the network cameras. VLANs normally provide a better and more cost-efficient solution than a separate network. The primary protocol used when configuring VLANs is IEEE 802.1Q, which tags each frame or packet with extra bytes to indicate which virtual network the packet belongs to.

In this illustration, VLANs are set up over several switches. First, each of the two different LANs are segmented into VLAN 20 and VLAN 30. The links between the switches transport data from different VLANs. Only members of the same VLAN are able to exchange data, either within the same network or over different networks. VLANs can be used to separate a video network from an office network.

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