[AG-TECH] Venues Addresses: infrastructural question, CHANGED TO: Bridging Problems

Fabrizio.Berdondini at prototipo.it Fabrizio.Berdondini at prototipo.it
Sat May 13 11:11:17 CDT 2006

Hello Andrew,
thank you for reply, as always clear and useful to me. The scenario you 
prospected to me is right the one I was thinking about as a "workaround" 
to the multicast problem. For this reason I first tried to configure a 
BridgeServer onto my VenueServer machine, but as far as now I'm still 
having some problems. 
Here is a description of what's happening.
First of all, the VenueServer runs onto a dual-boot (XP Pro - SUSE 10) 
machine, located at an externally visible IP I first tried 
to configure server and an experimental bridge for XP, so I created, 
following instructions found on AG portal, a BridgeServer.cfg file, with 
the following structure:
name = AGserver1
location = ReS
qbexec = c:\programmi\AGtk2.4\bin\QuickBridge.exe
portMin = 40000
portMax = 60000
# VenueServer
type = VenueServer
# Centro Monitoraggio Pazienti
type = Venue

I tried to mutually exclude the bridging of the Venue or that of the 
VenueServer. In both cases, however, even if the bridge seems running, it 
doesn't do his job: if 2 users connect their client to the bridged venue 
they are able to switch to unicast mode choosing the bridge server, but 
after that each one can see only audio/video that comes out from his 
machine, no audio/video from the other. Is there something misconfigured 
into my .cfg?
Second question: i tryed to connect my 2.4 client to the venue:


then tried to switch to Unicast, the msgbox for let me choose a bridge 
raised up and I selected:


but after that I got the following error:

"Use Unicast Error"
"Stream Information for selected bridge not found; reverting to previous 

Only some more internal venue allowed me to use unicast with a bridge, but 
connecting to it with a fellow of mine who enabled unicast too, we are 
unable to get audio/video streams: each one of us seems to be the only 
audio/video stream inside the venue.

As always thank you for your support,
Faber B.

owner-ag-tech at mcs.anl.gov scritti il 12/05/2006 13.40.20

> Hi,
> I am not sure if it is possible to tunnel an entire venue server.
> What would be useful would be to have a bridge server hosted on a 
> multicast enabled network.  This bridge server would allow you to 
> use the venue client in “unicast” mode.  This would make a unicast 
> connection to the bridge server and then the bridge server would 
> make the multicast connection.
> You are welcome to use the AGSC venue server just now to try this out (
> https://ag2server.ag.manchester.ac.uk/Venues/default).  This is an 
> AGTk version 2.4 venue server, but we are bringing an experimental 
> AGTk 3.0 server on line within a week (hopefully).  All venues on 
> our server are bridged, although it is worth noting that this is 
> still running as a “best efforts” server in that we try our best to 
> keep it running at all times, but don’t guarantee that it is.
> If this works out, there may be scope for adding more venues, 
> although I will have to speak to my team here to see if this is 
> possible.  In this case, we would need a set of multicast addresses 
> that you would want to use for the venues anyway – we don’t have any
> spare ones to use.
> I don’t think there are any specific requirements to set up 
> multicast routing, but I am not an expert in this field.  I would 
> guess that you need your router, and every router between yours and 
> another multicast router to be multicast enabled.  I would then 
> think that each router needs to know about the other multicast 
> routers, although this may be done using a protocol, I am not too sure.
> Let me know if I can help any more,
> 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: Fabrizio.Berdondini at prototipo.it [mailto:Fabrizio.
> Berdondini at prototipo.it] 
> Sent: 12 May 2006 09:08
> To: Andrew.Rowley at manchester.ac.uk
> Cc: ag-tech at mcs.anl.gov
> Subject: RE: [AG-TECH] Venues Addresses: infrastructural question
> 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' houses/hospitals. 
> 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 12.44.34
> > 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 
> information. 
> > Thanx as always, 
> > Faber B. 
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