Multicast configuration at layer 3 and Webex/Skype

[wfqk]

Hi I have question. Every one has experience to have meeting online via Skype, or Webex etc. These kind of application is very convenient for us to communicate or send some video to many site.

We also can configure multicast at layer 3 to do this kind of thing. But multicast configuration is relatively complicated. Do you think Webex or Skype can replace multicast configuration? Thank you

[Reza Sharifi]

Hi,

To use WebEx and Skype, you don't need multicast.  They both work with unicast.

HTH

[wfqk]

Thanks for your reply. The question might not be clear. There are two ways to send stream. One is that we can configure multicast at layer3 to send stream, and second is that we can use Webex to send the stream.

if we use Webex, it would be very easy and we do not need to configure multicat at layer3. However some people still need to configure multicast, why? 

[Reza Sharifi]

Hi,

I am not sure why some people still need to configure multicast. Video portion of WebEx is a unicast based application whether you use it in the cloud or on prem and the audio portion is just a phone call to a conference bridge Cisco or a 3rd part vendor assign to you.

HTH

[Richard Burts · Accepted solution]

I agree with Reza that once you make the choice to use WebEx there is no need to configure multicast. I believe that what the original poster is really trying to ask is about the choice to use WebEx or to use multicast - noting that some organizations have chosen to use multicast and therefore need to configure multicast.

The answer to this has to do with scalability. Or perhaps we can look at it as a choice between convenience and efficiency. Think about an organization that has a video that they want people to see and assume that there are 100 people who need to see the video. When using WebEx for every frame that the video server sends out the WebEx server will generate 100 unicast copies and the network will deliver the 100 copies to the destinations. When using multicast for every frame that the video server sends out the network will send 1 multicast frame which will reach the destinations.

So do you choose to use WebEx which is convenient but makes the network work harder? Or do you choose multicast which is a bit more complicated but reduces the load on the network?

HTH

Rick

[wfqk]

Richard, Thank you so much. Understood. This is difference between unicast and multicast. 

[Richard Burts]

You are welcome. I am glad that my explanation was helpful.

Yes it is the difference - unicast is easy but not so efficient and multicast is more complex and more efficient at delivering the data.

HTH

Rick