[ofa-general] Re: OpenSM detection of duplicated GUIDs on loopback

[Hal Rosenstock]

On 7/24/07, Eitan Zahavi <eitan at mellanox.co.il> wrote:
>
>  *From:* Hal Rosenstock [mailto:hal.rosenstock at gmail.com]
> *Sent:* Tuesday, July 24, 2007 5:53 PM
> *To:* Eitan Zahavi
> *Cc:* OpenFabrics General; Sasha Khapyorsky; Yevgeny Kliteynik
> *Subject:* Re: OpenSM detection of duplicated GUIDs on loopback
>
>
>
> Hi Eitan,
>
> On 7/24/07, Eitan Zahavi <eitan at mellanox.co.il> wrote:
> >
> >  *Hi Hal,*
> > **
> > *What is this "loopback" connector used for?*
> > *Does not seem to me like a very useful thing to do.*
> >
> **
> Perhaps not but no reason OpenSM can't handle this more gracefully.
>
>  *Anyway, if it is not a production environment we could add a "debug
> > mode" (-d flag option) to ignore this check.*
> >
> **
> Why would a separate flag be needed ?
> *[EZ] Since I do not see any other solution for the SM  to know it is
> really a loop back plug rather then two devices with same GUID connected
> back to back ...*
>
>
"Technically", this should only occur when looped back and not two devices
with same GUID as GUID == globally unique and a duplication indicates a
"manufacturing" issue.

Anyhow, can't these be treated the same (and handled more gracefully)
without an additional option/flag ?

-- Hal


> -- Hal
>
>  **
> >
> > *Eitan Zahavi***
> > Senior Engineering Director, Software Architect
> > Mellanox Technologies LTD
> > Tel:+972-4-9097208
> > Fax:+972-4-9593245
> > P.O. Box 586 Yokneam 20692 ISRAEL
> >
> >
> >  ------------------------------
> > *From:* Hal Rosenstock [mailto:hal.rosenstock at gmail.com]
> > *Sent: *Tuesday, July 24, 2007 5:31 PM
> > *To:* OpenFabrics General
> > *Cc:* Sasha Khapyorsky; Eitan Zahavi; Yevgeny Kliteynik
> > *Subject:* OpenSM detection of duplicated GUIDs on loopback
> >
> >
> >  Hi,
> >
> > This is what starts off as a "minor" issue and I know it has been
> > discussed it somewhat in the past:
> >
> > Putting a loopback connector on a (switch) link causes OpenSM to
> > indicate duplicated GUID error 0D18 as follows:
> >
> > __osm_ni_rcv_set_links
> > {
> > ...
> >           /*
> >              When there are only two nodes with exact same guids
> > (connected back
> >              to back) - the previous check for duplicated guid will not
> > catch
> >              them. But the link will be from the port to itself...
> >              Enhanced Port 0 is an exception to this
> >           */
> >           if ((osm_node_get_node_guid( p_node ) ==
> > p_ni_context->node_guid) &&
> >               (port_num == p_ni_context->port_num) &&
> >               (port_num != 0))
> >           {
> >             osm_log( p_rcv->p_log, OSM_LOG_ERROR,
> >                      "__osm_ni_rcv_set_links: ERR 0D18: "
> >                      "Duplicate GUID found by link from a port to
> > itself:"
> >                      "node 0x%" PRIx64 ", port number 0x%X\n",
> >                      cl_ntoh64( osm_node_get_node_guid( p_node ) ),
> >                      port_num );
> > ...
> >
> > So this occurs over and over and over and fills the log with the same
> > spew. This should be improved IMO.
> >
> > Is this really a fatal condition ? Doesn't seem like it should be to me.
> >
> >
> > Also, OpenSM can "ride" this out with -y (stay on fatal) but is that
> > safe for this condition ?
> >
> > Seems like something like an extra loopback bit should be added to some
> > port structure which should cause these links to be ignored. This bit would
> > then be reset when the peer is now longer itself.
> >
> > Also, is there a relationship of this with the 12x/duplicated GUID code
> > ?
> >
> > Thanks.
> >
> > -- Hal
> >
> >
>
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