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From: Christian Kauhaus (ckauhaus_at_[hidden])
Date: 2006-09-06 11:44:23

Bogdan Costescu <Bogdan.Costescu_at_[hidden]>:
>I don't know why you think that this (talking to different nodes via
>different channels) is unusual - I think that it's quite probable,
>especially in a heterogenous environment.

I think the first goal should be to get IPv6 working -- and this is much
more easier when we restrict ourselves to the case when all system
participating in one(!) job are reachable via a single protocol version,
either IPv4 or IPv6.

I'm not quite sure if we need to run a *single* job across a network
with both systems that are not reachable via IPv4 and systems
that are not reachable via IPv6. If there is a practical need for this,
we will probably tackle this in the future. Note that the current plan
does not restrict the use of OpenMPI in heterogenous IPv4/IPv6
environments, but we will not support mixed IPv4/IPv6 operation in a
single job right now.

Our current plan is to look into the hostfile and see if there are

(1a) just IPv4 addresses
(1b) IPv4 addresses and hostnames for which 'A' queries can be resolved
(2a) just IPv6 addresses
(2b) IPv6 addresses and hostnames for which 'AAAA' queries can be resolved.

In case 1 we initially use an IPv4 transport and in case 2 we initially
use an IPv6 transport for the oob. If neither case 1 or 2 are possible,
we abort.

I hope that all can agree that this is a good starting point.


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