At 01:17 PM 10/23/2007, Steve Wise wrote:
Sean Hefty wrote:
There has been much discussion on a private thread regarding bug #735 -
"dapltest performance tests don't adhere to iWARP standard" that needs
to move to the general list.
This bug would be better titled "iWarp cannot support uDAPL API". :)
Seriously, the iWarp and uDAPL specs conflict. One needs to change.
Can someone come up with a solution, possibly in iWARP CM, that will
work and insure interoperability between iWARP devices?
I thought the restriction was there to support switching between
streaming and rdma mode. If a connection only uses rdma mode, is the
restriction really needed at all?
Yes because all iWARP connections start out as TCP streaming mode
connections, and the MPA startup messages are sent in streaming mode. Then
the connection is transitioned into FPDU (Framed PDU) mode using the MPA
protocol.
Correct. The IETF was very clear on these requirements (significant debate
occurred over at least 12-18 months) and there is unlikely to be any
traction in changing the iWARP specifications to provide another
mechanism. Best to provide API that detect which semantics are required
and then if the application cannot adjust, then it cannot use the iWARP
semantics.
BTW, if one uses the SDP port mapper protocol (see the IETF SDP
specification), one can detect from the start that RDMA is being used and
one could start in RDMA mode sans the MPA requirement. The SDP port
mapper protocol also enables one to apply various other policies such as
determining whether the application / remote node session should be allowed
to run over RDMA or not - simple point of control for management.
Mike
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