Lorraine, see our Multicasting Surveillance Tutorial and Multicasting Problem With VMS for two posts with more information.
Those should address your questions. If not, feel free to follow up.
thanks John. I have reviewed those posts and that is the reason I asked. The "Multicasting Problem with VMS" has a statement:
"They do not recommend feeding only a multicast stream from the device because of the difficulties encountered in troubleshooting multicast streams if there are problems."
Are you referring to difficulties in troubleshooting MC over the data network? and if so, is that the primary reason why people are avoiding MC? because the network makes it to difficult?
I agree, the only time you would consider MC is if you are having throughput issues. And then as discussed above it depends on your system design. If you have multiple clients viewing streams in one location then it might be good. If your users are dispersed geographically then it might not be the best concept.
To answer your question on why MC over a network is diffucult is that a misconfigured MC network will flood your network with unwnanted traffic and end up doing more damage to what you are try to fix.
thanks for the insight. It would seem though, that if the network wasn't an issue at all, using MC would be the preferred method. If multicast was configured the same way as unicast, and didnt present additional challenges in the network, then why use unicast at all? it seems like the industy has designed around MC beause of the difficulty in configuring it on the network and has pushed the use of MC into the realm of specific use cases because of that. Anyway, thanks for the comments
How would you reolve the issue of having multiple connection to a server for live viewing? 4 workstations in different offices with 19 cameras open 12 hours day?
One thing I must be mistaken about: Didn't at least half of the network bandwidth benefit of MC go out the window when everyone started using fast ethernet and other switching technologies that have private collision domains?
If the switch is routing each unicast on its own collision domain whats the advantage of using MC? I understand that the switch still has to process all the streams internally and the server has to generate them and the backhaul between the server and switch has to be able to carry them, but the LAN to the desktop itself shouldn't be impacted either way, no?
Hi Alain Bolduc
Yes it would seem you are correct.... although customers don't want excuses....
Hi Undisclosed (#0321091)
Situation is that the individual machines are running on 100% cpu with the cameras loaded... the idea would be that the multicast would broadcast the stream/vms like Wowza forwarding the streams as requested... the camera to the server is managable it's the requests from the clients that becomes an issue....
the entire camera network is subnetted ... the only addresses on the main network are for the NUUO NVR Mini and the Mainconsile. The Vivotek cameras being used do support multicast although the servers do not.
Possibly, will see how we go....
found these which in the interim which could resolve some of the issues and they support multicasting ...
Muxlab HDMI over IP Extender with PoE
500752-Tx [Encoder], 500752-Rx [Decoder]
Does the anticipated use of Video Analytics have a role to play in the Multicast vs. Unicast decision for a 1000+ camera site?
Analytics use could involve ad hoc tag & trace search across say more than 100 cameras and also scenario based analytics dedicated to individual cameras.