[Openib-windows] Voltaire IP Router interoperability patch

[Fabian Tillier]

Hi Guy,

On 5/29/06, Guy Corem <guyc at voltaire.com> wrote:
>
> Hi Fab,
>
> The following patch solves interoperability issue with Voltaire Ethernet to
> InfiniBand gateway.
>
> Please apply.

I'm trying to understand what the patch is trying to do.

When performing the endpoint lookup, it seems that the QPN is ignored
(that is, it is not updated in the endpoint if the WC shows a
different QPN than the current for that endpoint.

Then when receiving an ARP, the code flushes the endpoints as it used
to if the source GID and LID don't match.  The change revolves around
the QPN checks, and this is where I got confused.

The original code checked that the remote QPN in the WC matches the
QPN in the endpoint.  You added a check that for a voltaire router
GID, both the QPN in the WC and the QPN in the endpoint match the QPN
in the IPoIB source hardware address's QPN field.  I don't understand
this.

Are there cases where the hardware address in the ARP has a different
QPN than the sending QP?  It seems this check is stricter than the
original check.  Is this the right check to do for all endpoints (that
is, check for consistency between the sending QP and the ARP payload)?

Can you explain a bit the behavior of the Voltaire router with respect
to ARPs and QPNs?

Thanks,

- Fab