Subject: [rddp] Association of STag and RDMAP Stream(s)

From: Renato Recio <[email-masked]>
Date: Tue, 11 Feb 2003 10:05:51 -0600

Folks,
      A problem was raised on this reflector regarding the need for a
little more text describing the mechanisms the RDMAP layer may use to
associate an RDMAP Stream and an STag.

      Following is text I propose to add to bullet #5 in section 10.3 of
the -01 specification:

RDMAP MAY choose several locally defined mechanisms for associating a RDMAP
Stream and a STag. One such mechanism is to provide two association types:
a protection domain association and an RDMAP Stream association.

   Under the protection domain (PD) association, a unique protection domain
   identifier (PD ID) is created and used locally to associate the STag
   with a set of RDMAP Streams. Under this mechanism, only RDMAP Streams
   that have the same PD ID as the STag are allowed to use the STag. For an
   incoming RDMA Write or RDMA Read Response Message on an RDMAP Stream, if
   the PD ID associated with that RDMAP Stream is not the same as the PD ID
   associated with the STag targeted by the RDMA Write or RDMA Read
   Response Message (respectively), then the Message is not placed and the
   RDMAP Stream MUST be Terminated. For an incoming RDMA Read Request
   Message on an RDMAP Stream, if the PD ID associated with that RDMAP
   Stream is not the same as the PD ID associated with the Data Source
   STag, the Message is not placed and the RDMAP Stream MUST be Terminated.
   Finally, for a Send with Invalidate or Send with SE and Invalidate on an
   RDMAP Stream, if the PD ID associated with that RDMAP Stream is not the
   same as the PD ID associated with the STag that is to be Invalidated,
   the Message is not placed and the RDMAP Stream MUST be Terminated. Note
   that the PD ID is locally defined, and cannot be directly manipulated by
   the Remote Peer.

   Under RDMAP Stream association, a given RDMAP Stream is identified
   locally by a unique RDMAP Stream identifier (ID) and that RDMA Stream ID
   is associated with the STag and RDMAP Stream. In this case, for an
   incoming RDMA Write or RDMA Read Response Message on an RDMAP Stream, if
   the RDMAP Stream ID associated with that RDMAP Stream is not the same as
   the RDMAP Stream ID associated with the STag targeted by the RDMA Write
   or RDMA Read Response Message (respectively), then the Message is not
   placed and the RDMAP Stream MUST be Terminated. Similarly, for an
   incoming RDMA Read Request Message on an RDMAP Stream, if the RDMAP
   Stream ID associated with that RDMAP Stream is not the same as the RDMAP
   Stream ID associated with the Data Source STag, then the Message is not
   placed and the RDMAP Stream MUST be Terminated. Finally, for a Send with
   Invalidate or Send with SE and Invalidate on an RDMAP Stream, if the
   RDMAP Stream ID associated with that RDMAP Stream is not the same as the
   RDMAP Stream ID associated with the STag that is to be Invalidated, the
   Message is not placed and the RDMAP Stream MUST be Terminated. Note that
   the RDMA Stream ID is locally defined, and cannot be directly
   manipulated by the Remote Peer.

I believe the above text resolves the problem, folks, please let me know if
you agree.

Thanks,

Renato J Recio
IBM Distinguished Engineer
Member IBM Academy of Technology
IBM I/O Architecture and Technology
Tel 512-838-3685, T/L 678-3685

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---

From: Caitlin Bestler <[email-masked]>
Date: Tue, 11 Feb 2003 11:09:18 -0600

On 2/11/03, Renato Recio wrote:

>
>
>
>
>Folks,
> A problem was raised on this reflector regarding the need
> for a little more text describing the mechanisms the
> RDMAP > layer may use to associate an RDMAP Stream and an
> STag.
>
> Following is text I propose to add to bullet #5 in
> section 10.3 of the -01 specification:
>
>

Two points:

First, I believe that validation of STags is a DDP issue,
not RDMAP. So the extra wording should go in *that* draft.

STag Invalidation may be performed by RDMAP, but validation
must be performed *before* placement, and therefore must be
handled by the DDP layer.

Second, I believe it should be made clear that this does not
imply a standard scope for an STag. The naming domain
obviously must be at least as large as the domain over which
it is valid, but it could be only that size, the scope of
the IP address, the subnet or whatever.

If you use an STag somewhere else, you have no guarantee
that you will not accidentally pick a valid value.

Caitlin Bestler
http://asomi.com/CaitlinBestler/
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