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From: Christian Kauhaus (ckauhaus_at_[hidden])
Date: 2006-04-03 13:13:32


Bogdan Costescu <Bogdan.Costescu_at_[hidden]>:
>I beg to disagree. In a setup like the one mentioned, after orted is
>started via an IPv4-only rsh/ssh, OpenMPI applications could use IPv6
>without problems, just like they could use f.e. GM if Myrinet cards
>would be present. I see this very much like your past experience with

Ok, I slowly get the point... ;-)

I see two possibilities concerning machinefile contents and how this
affects both rsh/ssh and OpenMPI.

1. Put IPv[46] addresses into the machinefile. Since they are
   protocol-specific, both rsh/ssh uses them just the way they are.
   OpenMPI performs interface discovery, possibly getting more
   addresses. The use of these addresses is controlled via runtime
   configuration.

2. Put hostnames into the machinefile. Both rsh/ssh and OpenMPI perform
   their own resolver lookup. When the resolver library gives both
   addresses (IPv4 and IPv6), which one to used is handled via OpenMPI
   runtime configuration. What rsh/ssh do depends on
   them. Note that you can specify an IP protocol selection at least
   with ssh (-4/-6 cmdline switches).

Your setup (IPv6 addresses given by the resolver, but no IPv6-aware ssh)
could be handled in both ways: either by putting numeric IPv4-addresses
into the machinefile, or by specifying 'ssh -4'.

Is this a solution?

 Christian

-- 
Dipl.-Inf. Christian Kauhaus                               <><
Lehrstuhl fuer Rechnerarchitektur und -kommunikation 
Institut fuer Informatik * Ernst-Abbe-Platz 1-2 * D-07743 Jena
Tel: +49 3641 9 46376  *  Fax: +49 3641 9 46372   *  Raum 3217