Multicast Address Assignment

I'm not sure I understand your question: Are you trying to set up multicasting on a network? IP addresses are IP addresses, regardless if they are unicast or multicast.

In my experience, the cameras and workstations have unicast IP addresses. In the video stream/profile settings, you assign a multicast IP address. Then, when the VMS/NVR connects, it pulls the multicast stream.

I have never had to configure a multicast address in the NVR/VMS. It always connects via the unicast IP address, but then streams via multicast.

I hope that makes sense....

I am talking of multicasting from the VMS to the clients.

@Aaron: Do you mean to say I will have to assign only unicast IP addresses to the network adaptors of the recording server and the client workstations? I dont think so.

Correct me if I am wrong.

Its Milestone XProtect Corporate 2014.

I know this is an old post, but given that I'm primarily a network guy, I figured someone might stumble upon this some day and need an actual answer.

Multicast is special, it doesn't work like normal network traffic. You do not assign a multicast address to a device, rather multicast is a destination address to which a device will transmit video. An endpoint will learn (either from the VMS or from a multicast announcement, called a SAP), the multicast address of a video stream. The endpoint will then request to join that stream.

The upstream switch will then check if it is already receiving that stream, and if so, copy it to the port that your endpoint is attached. If the switch isn't already receiving that stream, it will send the join up to it's parent switch and so on.

The key thing here is that the sending device only ever sends out 1 video stream, and each time the stream goes through the network, only 1 video stream is transmitted from one switch to the next. The switch itself is what creates copies of the stream and sends it only to the devices attached to it.

So, what do you need to make it work? First, your switches need to support and have enabled IGMP on each VLAN that will have multicast. Second, if you have layer 3 switches or routers, they'll need PIM enabled. You'll also need an IGMP querier, which is normally your layer 3 switch/router. Finally, you need to be sure that each device which is going to transmit multicast is doing so on a different multicast address. Normally your VMS will do that for you.

A bit of warning. If multicast on the network isn't configured properly, you can flood the network. Unmanaged switches or cheap managed switches often do not support multicast, so that single stream will get flooded to every port on the switch, which your endpoints might not appreciate.

In my experience, Multicasting is seldom used these days due to the complexity of setting it up (query mode, snoop mode, PIM, etc.). Lots of IT personnel no longer get trained on Multicast, and have difficulty setting it up.

In addition, the IT department must have switches with enough groups to support the number of cameras required. I'm not sure that this is still an issue, but in the early 2000s, many switches, especially 3-Com, were limited to the number of groups that they could support, and would flood the network when this limit was exceeded.

With the current crop of CPUs in recording servers, the ability to proxy out many streams to clients is very high, and we seldom see Multicast except for one-to many situations, such as large systems with multiple SOCs, and redundant recording where multiple recorders must record the same stream.