[openib-general] [RFC] IB address translation using ARP

[Roland Dreier]

    Sean> Can you explain how RDMA works in this case?  This is simply
    Sean> performing IP routing, and not IB routing, correct?  Are you
    Sean> referring to a protocol running on top of IP or IB directly?
    Sean> Is the router establishing a second reliable connection on
    Sean> the backend?  Does it simply translate headers as packets
    Sean> pass through in this case?

I think the usage model is the following: you have some magic device
that has an IB port on one side and "something else" on the other
side.  Think of something like a gateway that talks SDP on the IB side
and TCP/IP on the other side.

You configure your IPoIB routing so that this magic device is the next
hop for talking to hosts on the IP network on the other side.

Now someone tries to make an SDP connection to an IP address on the
other side of the magic device.  Routing tables + ARP give it the GID
of the IB port of this magic device.  It connects to the magic device
and run SDP to talk to the magic device, and the magic device
magically splices this into a TCP connection to the real destination.

Or the same idea for an NFS/RDMA <-> NFS/UDP gateway, etc.

 - R.