[AG-TECH] Venues Addresses: infrastructural question

Fabrizio.Berdondini at prototipo.it Fabrizio.Berdondini at prototipo.it
Fri May 12 03:08:22 CDT 2006

Thank you very much Andrew,
quite clear right now....

And now the question is...

We are studying the development of an infrastructure for reasearch 
purposes focused on domiciliar monitoring of patients with Alzheimer's 
desease, leaving in islands or difficult to reach areas. It will be 
developed in collaboration with the Italian Ministry Of Health and other 
public structures, such as ISS (Istituto Superiore Sanità). We thought to 
base it onto the AccessGrid infrastructure. Thus we would need to have a 
couple of VenueServers connected to the Mbone in order to provide 
connectivity via Multicast for each videoconference dedicated machine at 
patient's home and for a central "Call Center", connected, again via 
videoconference dedicated machines, to some caregivers'/medicians' 
Would it be possible, and eventually how, to "tunnell" our VenueServer(s) 
in order to link it/them to the Mbone? How, and which pre-requisites are 
needed in order to require/gain access to the Mbone infrastructure?
Thank you, as always, for your support,
Faber B.

"Andrew A Rowley" <Andrew.Rowley at manchester.ac.uk> scritti il 11/05/2006 

> Hi,
> As far as I understand it:
> 1) The IP is a real multicast IP, with global scope.
> 2) I think Argonne has reserved the IPs that they use with IANA.  If
> you want to run a venue server, I would advise you do the same, or 
> use your GLOP space.  At the AGSC we only use static addresses.  The
> server keeps track of the IPs in use internally – no talking is done
> between servers.
> 3) This is standard multicast routing.  Vic and rat communicate 
> directly with other vics and rats once they are running – the only 
> use the venue server to get the addresses (unless you are using 
> unicast, in which case there is a bridge somewhere in the middle. 
> This bridge takes your unicast traffic and forwards it to multicast,
> and vice versa).
> 4) Multicast address routing works differently from unicast address 
> routing.  Basically, your router must be multicast enabled to allow 
> multicast to work from outside the router.  It is possible that it 
> will allow multicast to work inside the LAN without this, but I am 
> not too sure.  Your network card will respond to both the 192 
> address assigned to it, and multicast addresses, provided it has 
> “joined” the multicast group i.e. it has sent and IGMP message to 
> the router saying that it wants to joint the group and receive 
> traffic addressed to that group.
> There may be some things that are not quite right in the above, but 
> I’m sure someone on the list will correct me if this is the case.
> Andrew J
> ============================================
> Access Grid Support Centre,
> RSS Group,
> Manchester Computing,
> Kilburn Building,
> University of Manchester,
> Oxford Road,
> Manchester,
> M13 9PL,
> UK
> Tel: +44(0)161-275 0685
> Email: Andrew.Rowley at manchester.ac.uk
> From: owner-ag-tech at mcs.anl.gov [mailto:owner-ag-tech at mcs.anl.gov] 
> On Behalf Of Fabrizio.Berdondini at prototipo.it
> Sent: 11 May 2006 08:29
> To: ag-tech at mcs.anl.gov
> Subject: [AG-TECH] Venues Addresses: infrastructural question
> Hello all, 
> while trying to resolve some troubles in our internal subnet 
> configuration, I was wondering how *exactly* the VenueServer 
> assigns/manages addresses for the venues. What I know, from official
> documentation and from Thomas D. Uram messages inside this m/list, 
> is that the management of the IP for the venues can be either static
> or dynamic, meaning that I can assign a fixed IP to each venue (one 
> for video, one for audio, and it will have always the same) or let 
> the venueserver assign the IPs inside a variable range, giving them 
> to audio/video of a venue when the first user asks to enter it, 
> while releasing them when the last person into the venue leaves it. 
> What I'm not able to understand is: 
> 1) is the IP assigned to audio/video for each room a *real* IP (a 
> multicast IP publicly visible over the internet i mean) or is there 
> some kind of alias/routing sistem underlying somewhere? 
> 2) In the first case, how can the venue server understand a 
> particular IP is "free" or "used" by someone else (i.e. another 
> venueserver or another service)? 
> 3) In the second case, how is the routing done? How can the 
> venueserver address the two applications Vic and Rat (with some kind
> of DNS i guess) to the right IP? 
> 4) Again in the second case, how can the VenueServer assign/manage 
> addresses in ranges like 224.xxx.xxx.xxx when the allowed IPs inside
> a LAN are restricted to a range that goes from to 
> I'm not sure if I could explain clearly what I'm looking for, but 
> this matter, as far as now, is very critical to me, I'm ready to 
> give any further clarification and open to every suggestion and 
> Thanx as always, 
> Faber B. 
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