[openib-general] IB Address Translation service

[Roland Dreier]

    Paul> Would this proposed address translation layer interface
    Paul> provide a sufficient subset of IPoIB functionality that
    Paul> allowed an SDP implementation to exist without a larger,
    Paul> full-featured IPoIB implementation?

I doubt it.  Right now the IPoIB driver has very little code related
to address translation.  It relies on the kernel's ARP layer to get it
remote addresses (GID + QPN) and then calls ib_sa_path_rec() to get an
actual IB path.  The second half of this translation is not even
really needed by SDP.  If you look at sdp_link.c in Libor's SDP
implementation you can see how this can work in a few hundred lines of
code.

Essentially all of the address translation used by SDP is done by the
kernel's ARP code, with the IPoIB driver serving to send and receive
ARP packets.

Presumably this proposed address translation library would also sit on
top of the kernel's IP stack and issue ARP requests as needed, so it
would still depend on the IPoIB driver.

 - Roland