On Feb 10, 2012, at 9:50 AM, Jeff Squyres wrote: > This is an open question to OMPI developers... > > It looks like RHEL (and maybe others?) adds the "virbr0" IP interface when > Xen is activated. This IP interface is only used to communicate with the > local Xen instance(s); it is not used to communicate over the real network. > > In a case that I saw, the interface is created, set to "up", and is given an > IP address in the 192.168.1.x range. This was done by default -- all the > user had done was either say "yes, I want Xen enabled", or he didn't say he > wanted it *disabled* (I'm not sure which). > > This causes a problem if you have Xen enabled on multiple machines in an OMPI > job. OMPI will see the 192.168.1.x address and see that it's "up", so it'll > add it to the eligible subnets that can be used. When OMPI sees that its > peer processes also have 192.168.1.x, it'll try to use that network for > OOB/BTL traffic -- which will fail, because these are local-only interfaces. > > Should we add "virbr0" to the default value for [btl|oob]_tcp_if_exclude?
How generic is that name? I've looked and can't find a way to detect a local-only interface, though you might be able to do it via ARP. Looking for a name, though, is pretty hit/miss. > > Or is there another way to detect that an interface is local-only and should > not be used for OOB/BTL communication? > > See this post on the user's list: > > http://www.open-mpi.org/community/lists/users/2012/02/18432.php > > -- > Jeff Squyres > jsquy...@cisco.com > For corporate legal information go to: > http://www.cisco.com/web/about/doing_business/legal/cri/ > > > _______________________________________________ > devel mailing list > de...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/devel
