All things related to multicast

[Marshall Eubanks <>]

Well, also it is very rare to have a multicast network failure on an  
ethernet LAN.

So

- if you want to test codecs, encodings, broadcaster settings, etc.,  
use unicast first
- if you want to test multicast config settings, like sdp files or  
proxy relays, do it on the lan the
servers are on
- use the network to test multicast routing once the first two are  
well in hand.

Of course, we are morphing more into debugging and trouble shooting...

Regards
Marshall

On Sep 28, 2007, at 12:33 PM, Richard Mavrogeanes wrote:

> Right.
>
> If it works going ten inches from Computer A to Computer B via  
> unicast,
> then it will work going from Computer A to millions of computers that
> are just like Computer B, provided the network (i.e. multicast) is
> right.
>
> So there is Computer A / Computer B compatibility (the codecs), and
> there is Computer A / Computer B protocol compatibility (the network).
> Since you must use a network to test fundamental Computer A /  
> Computer B
> codec compatibility, I think it best to use the most common network
> denominator which is unicast.
>
> /rich
>
>
> -----Original Message-----
> From: Frank Fulchiero 
> [mailto:]
> Sent: Friday, September 28, 2007 12:24 PM
> To: Richard Mavrogeanes
> Cc: wg-multicast
> Subject: Re: multicast testing etiquette
>
>
> On Sep 28, 2007, at 11:59 AM, Richard Mavrogeanes wrote:
>
> > Just one more comment to go along with Marshall:
>
> Hi Richard, I'll take as many as you can give!
>
>
> > There is no need to employ multicast to sort out codec / player
> > compatibility issues.  In fact, multicast (or the lack thereof)
> > tends to
> > confuse the codec issues, at least in the minds of the target  
> > viewers.
> > Why doesn't this work? Packet loss? Flooding? Routing? Or an oddball
> > codec?
>
> I think I understand. Are you saying that if a specific codec/
> implementation works in a specific OS/client software in http and
> rtsp it will work in multicast?
> That would also assume the SDP files, possible relays, and multicast
> network are correctly configured.
> So if it works in http/rtsp, and not in multicast, it must be an SDP
> or multicast network issue, right?
>
>
>
> > You may be better off doing http:// and rtsp:// server first,
> > discovering the codec compatibility.  Then, after you think all is
> > well,
> > releasing the multicast to the world community.  Generally, there  
> > is a
> > small number of folks willing to look at your stream for testing,
> > so the
> > problem multicast solves (global distribution) is not needed anyway.
>
> Good points, appreciate the feedback.
>
> Frank Fulchiero
> Digital Media Specialist
> Connecticut College