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<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>Hi Fab, please read my answers<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>Slava<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>-----Original Message-----<br>
From: Fab Tillier [mailto:ftillier@windows.microsoft.com] <br>
Sent: Tuesday, July 01, 2008 7:18 PM<br>
To: Sean Hefty; <st1:PersonName w:st="on">Slava Strebkov</st1:PersonName>;
ofw@lists.openfabrics.org<br>
Subject: RE: [ofw] [owf][patch] user multicast offload support</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>>>Voltaire has developed the LSP for Multicast Offload. Fast data
path<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>>>will use this service provider working on IB using ibal.dll.<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>>>Original service provider TCP/IPoIB is using to transfer IGMP
requests<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>>>to Ethernet routers which may be connected to IB host through
IPR.<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>>>IB join will come from user mode and from IPoIB too. The common
place<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>>>for them is in the ibal.lib.<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>>>To improve performance of HCA on receive path, IPoIB does not
issue<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>>>ATTACH to the group which already attached from user mode by LSP.<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>><o:p> </o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>>This leads me back to my original suggestion of simply having a<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>>parameter on the join multicast group that indicates if the QP
should be<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>>attached. This is way simpler and moves the complexity of
determining<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>>when to attach to the ULP, where it belongs.<o:p></o:p></span></font></p>
<p class=MsoPlainText><b><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-weight:bold'>Multicast group opened from user mode
is always attached. Attachment of groups from IPoIB depends on whether same
group was attached previously from user mode. IPoIB does not know this.<o:p></o:p></span></font></b></p>
<p class=MsoPlainText><font size=2 color=black face="Courier New"><span
style='font-size:10.0pt;color:black'><o:p> </o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>Even better us to let the client apps use the existing
ib_join/leave_mcast functions and internally detect whether the SA MC
registration needs to be done or not, as well as reference counting the SA MC
registration.<o:p></o:p></span></font></p>
<p class=MsoPlainText><b><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-weight:bold'>Implementing this will require
additional efforts; we’ll consider this later, in future releases.<o:p></o:p></span></font></b></p>
<p class=MsoPlainText><font size=2 color=black face="Courier New"><span
style='font-size:10.0pt;color:black'><o:p> </o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>Would you ever join a MC group without also attaching at least one QP?<o:p></o:p></span></font></p>
<p class=MsoPlainText><b><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-weight:bold'>Not yet<o:p></o:p></span></font></b></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>-Fab<o:p></o:p></span></font></p>
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