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Subject: Re: [OMPI devel] Additional excluded tcp inteface
From: Rolf Vandevaart (Rolf.Vandevaart_at_[hidden])
Date: 2008-11-07 16:27:15


On 11/07/08 11:23, Adrian Knoth wrote:
> On Fri, Nov 07, 2008 at 09:49:43AM -0500, Rolf Vandevaart wrote:
>
>> I do not think anyone will have a problem with this, but just thought I
>> would mention that I am planning on adding an additional interface to
>> the excluded list for the tcp btl. I want to add "sppp" to the list.
>> This is an internal interface to one of our servers and needs to be
>> treated like the "lo" interface.
>
> Is it possible to detect this interface and exclude it right from the
> beginning in opal/util/if.c? Special flags that apply to this interface,
> so we have a classification?
>
>
> Just my $0.02
>
I considered this. I believe the sppp0 is a "point-to-point" interface,
so I see that the IPv6 code has actually done something like this.

             if(0 != (cur_ifaddrs->ifa_flags & IFF_LOOPBACK)
                     || 0!= (cur_ifaddrs->ifa_flags & IFF_POINTOPOINT)) {
#if 0
                 printf("skipping loopback interface %s.\n",
cur_ifaddrs->ifa_name);
#endif
                 continue;
             }

However, the IPv4 code does not do this. In fact, the loopback check is
#ifdef'ed out.
#if 0
         if ((ifr->ifr_flags & IFF_LOOPBACK) != 0)
             continue;
#endif

So, in order for things to work properly in both case, I wanted to mimic
what was done for lo interfaces. I am leery about duplicating the IPv6
code in the IPv4 code as I looked at earlier discussions on the mailing
list saying that was a bad idea.

http://www.open-mpi.org/community/lists/devel/2008/02/3290.php

So, just adding it to the list of the excluded interfaces seemed the
safest fix to me.

Rolf

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