[rds-devel] [ofa-general] Re: Has anyone tried running RDS over 10GE / IWARP NICs ?

[Roland Dreier]

 > > Hmmm - so what happens with IWARP NIC when no buffer is posted on recv q and
 > > a message arrives ?
 > 
 > I am quite sure the L2 ethernet HW just drops it, but you better
 > verify this with an iWARP HW provider.

Why would it be dropped at L2?  What I believe will happen is that it
will generate an error at the DDP layer that will probably result in the
connection being closed.  Section 7.1 of RFC 5041 says:

   For non-zero-length Untagged DDP Segments, the DDP Segment MUST be
   validated before Placement by verifying:

["untagged DDP segments" are incoming send data, as vs. "tagged" RDMA
operations]

   2.  The QN and MSN have an associated buffer that allows Placement of
       the payload.

       Implementers' note: DDP implementations SHOULD consider lack of
       an associated buffer as a system fault.  DDP implementations MAY
       try to recover from the system fault using LLP means in a ULP-
       transparent way.  DDP implementations SHOULD NOT permit system
       faults to occur repeatedly or frequently.  If there is not an
       associated buffer, DDP implementations MAY choose to disable the
       stream for the reception and report an error to the ULP at the
       Data Sink.