[openib-general] Re: [swg] Re: private data...

[Fab Tillier]

> From: Michael Krause [mailto:krause at cup.hp.com]
> Sent: Thursday, October 20, 2005 10:00 AM
> 
> This is really an IBTA issue to resolve and to insure that backward
> compatibility with existing applications is maintained.  Hence, this exercise
> of who is broken or not is inherently flawed in that one cannot comprehend all
> implementations that may exist. Therefore, the spec should use either a new
> version number or a reserved bit to indicate that there is a defined format to
> the private data portion or not.   This is no different than what is done in
> other technologies such as PCIe.  Those applications that require the existing
> semantics will be confined to the existing associated infrastructure.  Those
> that want the new IP semantics set the bit / version and operate within the
> restricted private data space available.  It is that simple.

While I agree with you, the issue at hand is that DAPL tries to do both -
providing IP semantics to the application *and* 64-bytes of private data.  While
the IBTA may use a reserved bit to differentiate native IB or IP-enhanced
connection establishment MADs, if DAPL is to use this feature then DAPL clients
will lose some of their private data.  This gets us back to how to handle DAPL
clients that depend on the full 64 bytes of private data and how to support
them, which is a DAPL issue IMO and not an IBTA issue.  The IBTA should do
what's right for IB independently of DAPL, and define a proper IP-enhanced CM
protocol.

- Fab