Re: Local Peer and Remote Peer

Folks,

It appears the terms Local Peer and Remote Peer are used to mean two things
through-out the specification: at times RDMA/DDP protocol; and at other
times the ULP.

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



|---------+---------------------------->
|         |           Mike Ko          |
|         |           <[email protected]|
|         |           .com>            |
|         |           Sent by:         |
|         |           rddp-bounces@ietf|
|         |           .org             |
|         |                            |
|         |                            |
|         |           09/13/2005 07:34 |
|         |           PM               |
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  |       To:       [email protected]                                                                                         |
  |       cc:       [email protected], Renato Recio/Austin/IBM@IBMUS                                                   |
  |       Subject:  [rddp] Local Peer and Remote Peer                                                                     |
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In the course of updating the iSER draft, we found that the usage of the
terms "Local Peer" and "Remote Peer" as they relate to Advertisement is
not quite correct in both the RDMAP draft and the DDP draft.

In the RDMAP draft, "Local Peer" is defined as "The RDMA/DDP protocol
implementation on the local end of the connection" and "Remote Peer" is
similarly defined as "The RDMA/DDP protocol implementation on the opposite
end of the connection".  Under the definition of Advertisement, it states
that "advertisement of Tagged Buffer information is not defined by
RDMA/DDP and is left to the ULP".  For example, it is the iSER layer at
the local node that advertises the STag to the iSER layer at the remote
node by embedding the STag in a Send Message and the RDMAP/DDP layers send
the Send Message with no knowledge of the embedded STag.  However, In the
RDMAP draft, Advertisement is defined as "the act of informing a Remote
Peer that a local RDMA Buffer is available to it. A Node makes available
an RDMA Buffer for incoming RDMA Read or RDMA Write access by informing
its RDMA/DDP peer of the Tagged Buffer identifiers ...".  This should be
changed to "the act of informing the ULP of a Remote Peer that a local
RDMA Buffer is available to it.  A Node makes available an RDMA Buffer for
incoming RDMA Read or RDMA Write access by informing the ULP of its Remote
Peer of the Tagged Buffer identifiers ..."

Similarly,

The defintion of Tagged Buffer should refer to the "ULP of the Remote
Peer" instead of just "Remote Peer" and the revised definition should be
"A buffer that is explicitly Advertised to the ULP of the Remote Peer
through exchange of an STag, Tagged Offset, and length".

The defintion of Untagged Buffer should refer to the "ULP of the Remote
Peer" instead of just "Remote Peer" and the revised defintion should be "A
buffer that is not explicitly Advertised to the ULP of the Remote Peer."

"ULP Buffer" is currently defined as "A buffer owned above the RDMAP Layer
and advertised to the RDMAP Layer either as a Tagged Buffer or an Untagged
ULP Buffer".  This defintion is unclear since it does not mention whether
the RDMAP Layer refers to the local node or the remote node.  If the RDMAP
Layer refers to the remote node, then it is incorrect to state that the
Untagged buffer is advertised.  If the RDMAP is the local node, then usage
of the term "advertised" is incorrect since it is used in reference to a
remote node.  Perhaps it should be defined as "A buffer owned above the
RDMAP Layer and made available to the RDMAP Layer either as a Tagged
Buffer or an Untagged Buffer."

Mike

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