Page 26 - Security Today, February 2017

Unfortunately, multicast has minimal to no effect in situations where there are only a few recipients, different users want differ- ent video streams, or users want the video at different times. For these reasons, Multicast provides a benefit only in limited circum- stances for video surveillance.
In addition to its limited application in a VMS environment, multicast carries with it some additional planning and deploy- ment challenges:
• Transmission of multicast streams requires specialized net-
working equipment. Basic layer 2 switches may not have IGMP support required for multicasting. Network equipment
with this functionality typically costs more than comparable
network equipment, adding to the cost of the deployment.
• Cameras (usually) need to be multicast capable, which limits camera selection when deploying a multicast enabled video se- curity system. Most architectures involve the camera sending the multicast stream as opposed to the camera streaming uni-
cast to the VMS then the VMS sending the multicast stream. • If improperly configured, multicast data broadcasts to all de- vices on the network. A stream will be transmitted to each device on the network segment and the device must process
the data in order to determine what to do with it.
VMS BANDWIDTH
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