[openib-general] RDMA connection and address translation API

[Roland Dreier]

    Roland> No, I think we just need to realize that a perfectly
    Roland> transport neutral protocol implementation is not
    Roland> achievable.

    James> It is achievable. Although the IB and iWARP protocols are
    James> different, they can provide the same services to NFS-RDMA.

Not really.  This is just hiding the transport dependence in some
other layer and then pretending it doesn't exist.  IB and iWARP can
provide the same services to NFS/RDMA, but only through some
intermediate layer that implements the actual transport-dependent wire
protocol.

    James> IB is missing one service that iWARP has, namely that nodes
    James> can be identified with IP addresses. The ATS mechanism
    James> provides this capability for IB networks. If there are
    James> better mechanisms that do the same thing, then NFS-RDMA can
    James> use them.

All implementation of NFS/RDMA on top of IB had better interoperate,
right?  Which means that someone has to specify which address
translation mechanism is the choice for NFS/RDMA.

    James> The important things is not to push this up into the
    James> ULPs. The NFS-RDMA protocol is being standardized in the
    James> IETF. There is no reason to upset that process. If an
    James> additional IB specific protocol is necessary, it should be
    James> standardized in the IBTA.

NFS/RDMA is being defined on top of an abstract RDMA interface.
Someone has to write a spec for how that RDMA abstraction is
translated into packets on the wire for each transport that NFS/RDMA
will run on top of.

 - R.