[openib-general] mapping between IP address and device name

[Talpey, Thomas]

At 01:30 PM 6/24/2005, Roland Dreier wrote:
>    Thomas> But in the absence of one, I like what we have. Also, I do
>    Thomas> not want to saddle the NFS/RDMA transport with carrying an
>    Thomas> IP address purely for the benefit of a missing transport
>    Thomas> facility. After all NFS/RDMA works on iWARP too.
>
>I'm not sure I understand this objection.  We wouldn't be saddling the
>transport with anything -- simply specifying in the binding of
>NFS/RDMA to IB that certain information is carried in the private data
>fields of the CM messages used to establish a connection.  Clearly
>iWARP would use its own mechanism for providing the peer address.
>
>This would be exactly analogous to the situation for SDP -- obviously
>SDP running on iWARP does not use the IB CM to exchange IP address
>information in the same way the SDP over IB does.

Oh - I thought you meant that NFS/RDMA should have a HELLO message
carrying an IP address, like SDP/IB.

That's a nonstarter for the reason I mentioned, plus the fact that it links
this state to the connection, which might break and require reconnect.
In fact, NFSv4 and our Sessions proposal addresses this, but it doesn't
help NFSv3, which is the predominant use today.

On the other hand, placing a mandatory content in the CM exchange
brings in a whole different raft of interoperability questions, as James
mentioned earlier. For better or for worse, the ATS approach is easily
administered and does not impact any protocol layers outside of its
own. I think of it as ARP for IB.

Tom.