All things related to multicast

[Russ Hobby <>]

Hi Bill,

Good question.  I think that using the network for phone calls and using 
multicast are related but separate issues.  For conference calls, since the 
Internet2 edial system supports SIP calls, I usually do my conference calls 
over the network with a SIP softphone.  (you too can use SIP to do edial 
calls ;-)  I also use SIP to call other Internet2 staff. There is a bridge 
to the Internet2 POTS phones for staff member that are not yet using SIP.

However none of this is using multicast.  Why?  My feeling is it is because 
it is easier to set up a hub device or server to connect multiple people 
than to get multicast working right.  I think that this will be the case until

a) there are more people connecting to an application than a server or hub 
can handle easily (say a broadcast to LOTS of people) or

b) it is easier to use multicast than setting up a hub or server.

For many locations in Internet2 multicast is there, so having multicast 
available is not the issue.  However their is still a significant number of 
locations on campuses that do not have multicast (lack of demand network 
folk will say).  So if you want to set up a conference call, how do you 
make the best use of multicast and still accommodate those that do not have 
multicast available?  We can say that is an application problem, and indeed 
it is, but often the applications developer will say, "I will need a hub to 
handle those that do not have multicast and that can handle everyone so why 
should I bother with multicast?"  There has to be a real win for the 
applications developer to use multicast.

Now if we could come up with a highly desirable but not critical 
application that is only available via multicast that could kick things 
off.  Still if it were desirable enough people might just create gateways 
for unicast people to use.

I don't know what the answer is other than make it so easy they would not 
think other than using multicast.

Russ

At 08:18 AM 5/13/2004, Bill Owens wrote:
> I'm sitting at my desk now waiting to hear from someone to get a new 
> access code for a conference bridge, for a standing weekly call with a 
> bunch of folks involved in the MAN LAN project. I have another one for a 
> different project on tuesday afternoons, again with all I2-connected 
> people. Lots of one-time calls for specific things, too. And I realized 
> that they are all done over conventional phone bridges - never using the 
> network.
>
> Wonder why that is? We have VRVS, which I've never used, but it looks 
> nice. There's rcbridge for people who don't have multicast. Nearly 
> everyone has a computer with a microphone jack, and some have cameras to 
> boot. Most people should have enough bandwidth. But we always have 
> conference calls. . .
>
> Bill.