[AG-TECH] Avoiding problems - Multicast groups and also unicast bridges

Andrew A Rowley Andrew.Rowley at manchester.ac.uk
Mon Nov 20 08:58:15 CST 2006


In relation to the original question, the only way to ensure that you don't pick the same multicast addresses as another venue server is to use a different multicast range.  We use static addressing, using various multicast GLOP spaces we have access to, and some IANA assigned addresses.

There is a way to run a bridge behind a firewall without causing any delays, but note that this will require the client to be configured as well.  What you can do is run your own bridge registry as follows:

1) Create a text file that contains the IP address and port of the registry peer.  Put this text file on a web server so that it can be accessed by venue clients.  This web server is your bridge registry.

2) Locate the file RegistryPeer.py on your computer.  This is not usually in your AG bin directory, but is usually in your Python installation directory in site-packages/AccessGrid/Registry/RegistryPeer.py.

3) Windows Only: Add the following lines to the file before the line that reads "from AccessGrid.AGXMLRPCServer import AsyncAGXMLRPCServer"
    import agversion

4) Run:
       RegistryPeer.py -u <your-registry-url>
   where <your-registry-url> is the url set up in step 1.

5) Run your bridge(s) with the same -u option as above

6) Edit the AG client preferences file 
(Windows: c:\documents and settings\<username>\Application Data\AccessGrid3\Config\preferences; 
Linux: <home-dir>\.AccessGrid3\Config\preferences)
and change the line starting:
    bridgeServer = http://www.accessgrid.org/registry/peers.txt
to point to your registry url set up in step 1.

Now when you start the venue client, you should be using only your own bridge registry.

Andrew :)

Access Grid Support Centre,
RSS Group,
Manchester Computing,
Kilburn Building,
University of Manchester,
Oxford Road,
M13 9PL, 
Tel: +44(0)161-275 0685
Email: Andrew.Rowley at manchester.ac.uk 

> -----Original Message-----
> From: owner-ag-tech at mcs.anl.gov [mailto:owner-ag-tech at mcs.anl.gov] On
> Behalf Of Michael Groufsky
> Sent: 19 November 2006 21:46
> To: ag-tech at mcs.anl.gov
> Subject: Re: [AG-TECH] Avoiding problems - Multicast groups and also
> unicast bridges
> I also am curious about this.  Is there any way of setting up an AGTK 3
> bridge behind a firewall, without causing delays for others?
> -- Michael Groufsky
> Assistant Hardware Engineer
> HIT Lab NZ
> Joseph Stone wrote:
> > As a last step in getting a FC5 AGTK 3.0 Venue Server up, I have two
> > questions that deal with avoiding problems
> >
> > 1) How do people pick multicast addresses and ports such that they
> > don't use what someone else is using already?  It looks like the tool
> > will dynamically pick addresses / ports or give an option to pick
> > static ones, something I think we prefer to do.  Is this a good thing
> > to do?
> >
> > 2) I want my unicast bridge to be used only by people who VPN into my
> > server (I think).  If it is behind a firewall, I know that I'll
> > contribute to the long delays AGTK 3.0 Client users will experience.
> > Can I tell the bridge to not let anyone know that it exists (except
> > those joining my venue, of course)?
> >
> > Sorry if this has been answered in FAQs or mailing list, I've tried to
> > find this information for sometime.  If it is there, point me towards
> > it.  I'll develop better search techniques based on the pointer.
> >
> > Joe
> >
> >
> > Joseph Stone
> >
> > Senior Informatics Manager
> >
> > Family Medicine Community Health, Medical School, Univ. of Minnesota
> >
> > Suite 220 Dinnaken
> >
> > 925 Delaware St. SE
> >
> > Minneapolis, MN 55414
> >
> >
> > (612) 624-3192
> >
> > stone004 at umn.edu <mailto:stone004 at umn.edu>
> >
> >

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