> So? There are substantial semantic differences for *all* non-rdmacm
applications. Even common ones like OpenMPI. You propose to ignore them?

On the contrary! Any application that *does* care what the link layer is
can look up a new field in port_attr (rather than a new node transport
type).
Applications that don't, both old and new, can continue as normal - no
changes to the code are required.

>> RDMAoE *is* IB transport over Ethernet - we don't want different 
>> devices with different node types exactly for this reason: 
>> applications shouldn't care if they are running over IB or RDMAoE,
and 
>> shouldn't add another switch statement to support RDMAoE.

> Nonsense. RDMAoE is no such thing, it is utterly incompatible with the
IB management model. It is some new protocol that is only about 90%
compatible with IB.

You are missing the point here - RDMAoE is 100% compatible with IB at
the *transport* level, as reflected by the Verbs.
The point that the management model is different is true, but
irrelevant. The only transport-related issue that matters is addressing,
but for user-space apps, it is completely abstracted by the rdmacm.

Non-rdmacm apps fall into 2 main categories:
1. IB management+diagnostics apps - these are irrelevant for an Eth
network anyway.
2. High-performance middleware such as MPI and SHMEM - these perform
optimizations according to the link protocol anyway.

So, all relevant apps will work great with either IB or RDMAoE, in a
transparent manner.
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