Bogdan Costescu <bogdan.coste...@iwr.uni-heidelberg.de>: >What you propose here should work for the case of a single BTL that >handles both IPv4 and IPv6. How about the case of 2 BTLs ? (as it's >not clear to me from the rest of the discussion if one solution is >better than the other)
The introduction of a new 'tcp6' BTL was mentioned several times in the discussion. This would result in an enormous amount of duplicated code, since the IPv4->IPv6 transition would only affect a small fraction of the total tcp BTL codebase. This is clearly a violation of the DRY principle (don't repeat yourself). >Myrinet at the same time with GM over Myrinet, which also brings it to >2 (or even 3) protocols over the same physical connection. So how >should these situations be handled ? (this is more of a general >question, not related to IPv6 implementation). Very good point. Since we do not have Myrinet or IB in our institute clusters, I cannot tell. Experiences and suggestions from others? >Err, it's not OpenMPI, but the rsh/ssh client that tries the >connections. My point however is a bit different as it also relates to >the authentication behind the connection, where the IP (and therefore >its flavour) which is used for making the connection counts: When using rsh for startup, any interference between IPv6 and rsh/ssh is beyond the scope of OpenMPI. I really don't know which part of the OpenMPI code base is able to influence how rsh will authenticate some addresses. If rsh/ssh cannot handle or authenticate IPv6 connections, the admin must keep the IPv6 addresses out of the resolver, so that getaddrbyhost() never returns an IPv6 address. That's it. >> For example, we ran several weeks without an IPv6-enabled rsh, which >What do you mean by "IPv6-enabled rsh" ? Was it the daemon, client or >both ? We had both client and server IPv6-enabled and IPv6 addresses in the resolver, but the server did not listen on the IPv6 socket, resulting in a connection failure for IPv6. The subsequent connection attempt with the IPv4 address did succeed though. 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
