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<DIV><SPAN class=149310819-25072007><FONT face="Palatino Linotype"
color=#0000ff><STRONG>Hi Shirley,</STRONG></FONT></SPAN></DIV>
<DIV><SPAN class=149310819-25072007><STRONG><FONT face="Palatino Linotype"
color=#0000ff></FONT></STRONG></SPAN> </DIV>
<DIV><SPAN class=149310819-25072007><STRONG><FONT face="Palatino Linotype"
color=#0000ff>I think I understand where your question comes
from...</FONT></STRONG></SPAN></DIV>
<DIV><SPAN class=149310819-25072007><STRONG><FONT face="Palatino Linotype"
color=#0000ff>Many have issue with heterogonous fabrics where not all nodes have
same MTU or Speed.</FONT></STRONG></SPAN></DIV>
<DIV><SPAN class=149310819-25072007><STRONG><FONT face="Palatino Linotype"
color=#0000ff>Especially when IPoIB relies on all nodes joining the broadcast
group.</FONT></STRONG></SPAN></DIV>
<DIV><SPAN class=149310819-25072007><STRONG><FONT face="Palatino Linotype"
color=#0000ff></FONT></STRONG></SPAN> </DIV>
<DIV><SPAN class=149310819-25072007><STRONG><FONT face="Palatino Linotype"
color=#0000ff>The term "join" for multicast groups is a little
overloaded.</FONT></STRONG></SPAN></DIV>
<DIV><SPAN class=149310819-25072007><STRONG><FONT face="Palatino Linotype"
color=#0000ff>If a node joins an existing MC group it has to have a rate (speed
* width) > MCG.rate and support MTU > MCG.MTU otherwise it is
denied.</FONT></STRONG></SPAN></DIV>
<DIV><SPAN class=149310819-25072007><STRONG><FONT face="Palatino Linotype"
color=#0000ff>If the join is actually a "create" the node has to provide the
rate and MTU which define the MCG values.</FONT></STRONG></SPAN></DIV>
<DIV><SPAN class=149310819-25072007><STRONG><FONT face="Palatino Linotype"
color=#0000ff></FONT></STRONG></SPAN> </DIV>
<DIV><SPAN class=149310819-25072007><STRONG><FONT face="Palatino Linotype"
color=#0000ff>To allow for administrator to control the IPoIB MCGs MTU
and rate OpenSM provides the means to control these</FONT></STRONG></SPAN></DIV>
<DIV><SPAN class=149310819-25072007><STRONG><FONT face="Palatino Linotype"
color=#0000ff>values per partition. See the
doc/partition-config.doc</FONT></STRONG> </SPAN></DIV>
<DIV><SPAN class=149310819-25072007><STRONG><FONT face="Palatino Linotype"
color=#0000ff>Still the administrator should know what would be the lowest MTU
and rate the nodes expected to join the IPoIB subnet
have.</FONT></STRONG></SPAN></DIV>
<DIV><SPAN class=149310819-25072007><STRONG><FONT face="Palatino Linotype"
color=#0000ff>The tradeoff is in the hands of the administrator who can set a
value that will prevent slow nodes from joining the group,
</FONT></STRONG></SPAN></DIV>
<DIV><SPAN class=149310819-25072007><STRONG><FONT face="Palatino Linotype"
color=#0000ff>or assign a low value that will fit all nodes but slow down
communication ...</FONT></STRONG></SPAN></DIV>
<DIV><SPAN class=149310819-25072007><STRONG><FONT face="Palatino Linotype"
color=#0000ff></FONT></STRONG></SPAN> </DIV>
<DIV><SPAN class=149310819-25072007><STRONG><FONT face="Palatino Linotype"
color=#0000ff>EZ</FONT></STRONG></SPAN></DIV><!-- Converted from text/rtf format -->
<P><SPAN lang=en-gb><B><I><FONT face="Monotype Corsiva" color=#0000ff
size=6>Eitan Zahavi</FONT></I></B><I></I></SPAN> <BR><SPAN lang=en-gb><FONT
face=Tahoma size=2>Senior Engineering Director, Software Architect</FONT></SPAN>
<BR><SPAN lang=en-gb><FONT face=Tahoma size=2>Mellanox Technologies
LTD</FONT></SPAN> <BR><SPAN lang=en-gb><FONT face=Tahoma
size=2>Tel:+972-4-9097208<BR>Fax:+972-4-9593245</FONT></SPAN> <BR><SPAN
lang=en-gb><FONT face=Tahoma size=2>P.O. Box 586 Yokneam 20692
ISRAEL</FONT></SPAN> </P>
<DIV> </DIV><BR>
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<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> general-bounces@lists.openfabrics.org
[mailto:general-bounces@lists.openfabrics.org] <B>On Behalf Of </B>Hal
Rosenstock<BR><B>Sent:</B> Wednesday, July 25, 2007 10:01 PM<BR><B>To:</B>
Shirley Ma<BR><B>Cc:</B> general@lists.openfabrics.org<BR><B>Subject:</B>
[ofa-general] Re: openSM: Different IB MTUs<BR></FONT><BR></DIV>
<DIV></DIV>Shirley,<BR><BR>
<DIV><SPAN class=gmail_quote>On 7/25/07, <B class=gmail_sendername>Shirley
Ma</B> <<A href="mailto:xma@us.ibm.com">xma@us.ibm.com</A>>
wrote:</SPAN>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">
<DIV>
<P>Hal,<BR><BR>Thanks for your prompt reply. I am asking for how openSM
handle different link MTUs in SA MCMemberRecord MTU. For example, if we have
some links MTU as 2K, some links MTU as 1K. Then when enabling IPoIB, how
does SM decide IPoIB broadcast group MCMemberRecord MTU size? When creating
an IB multicast group from a 2K MTU node first, which PMTU value is
attaching to this IB multicast group MCMemberRecord MTU?
</P></DIV></BLOCKQUOTE>
<DIV> </DIV>
<DIV>MCMemberRecord MTU gets the group MTU (when created). This is either this
first joiner with sufficient components or preconfigured (and MTU can be set
in the config). If a joiner has insufficient MTU for the group, it is denied.
</DIV>
<DIV> </DIV>
<DIV>-- Hal</DIV>
<DIV> </DIV><BR>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">
<DIV>
<P>Thanks<BR>Shirley Ma<BR><BR><IMG height=16
alt='Inactive hide details for "Hal Rosenstock" <hal.rosenstock@gmail.com>'
src="cid:149310819@25072007-1403" width=16 border=0>"Hal Rosenstock" < <A
onclick="return top.js.OpenExtLink(window,event,this)"
href="mailto:hal.rosenstock@gmail.com"
target=_blank>hal.rosenstock@gmail.com</A>><BR><BR><BR>
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<UL>
<UL>
<UL>
<UL><B><FONT size=2>"Hal Rosenstock" <<A
onclick="return top.js.OpenExtLink(window,event,this)"
href="mailto:hal.rosenstock@gmail.com"
target=_blank>hal.rosenstock@gmail.com</A>></FONT></B><FONT
size=2> </FONT>
<P><FONT size=2>07/25/07 10:57 AM</FONT></P></UL></UL></UL></UL></TD>
<TD width="60%">
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<TR vAlign=top>
<TD width="1%"><IMG height=1 alt=""
src="cid:149310819@25072007-140A" width=58 border=0><BR>
<DIV align=right><FONT size=2>To</FONT></DIV></TD>
<TD width="100%"><IMG height=1 alt=""
src="cid:149310819@25072007-140A" width=1 border=0><BR><FONT
size=2>Shirley Ma/Beaverton/IBM@IBMUS</FONT></TD></TR>
<TR vAlign=top>
<TD width="1%"><IMG height=1 alt=""
src="cid:149310819@25072007-140A" width=58 border=0><BR>
<DIV align=right><FONT size=2>cc</FONT></DIV></TD>
<TD width="100%"><IMG height=1 alt=""
src="cid:149310819@25072007-140A" width=1 border=0><BR><FONT
size=2><A onclick="return top.js.OpenExtLink(window,event,this)"
href="mailto:general@lists.openfabrics.org"
target=_blank>general@lists.openfabrics.org</A></FONT></TD></TR>
<TR vAlign=top>
<TD width="1%"><IMG height=1 alt=""
src="cid:149310819@25072007-140A" width=58 border=0><BR>
<DIV align=right><FONT size=2>Subject</FONT></DIV></TD>
<TD width="100%"><IMG height=1 alt=""
src="cid:149310819@25072007-140A" width=1 border=0><BR><FONT
size=2>Re: openSM: Different IB MTUs</FONT></TD></TR></TBODY></TABLE>
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<TR vAlign=top>
<TD width=58><IMG height=1 alt=""
src="cid:149310819@25072007-140A" width=1 border=0></TD>
<TD width=336><IMG height=1 alt=""
src="cid:149310819@25072007-140A" width=1
border=0></TD></TR></TBODY></TABLE></TD></TR></TBODY></TABLE>
<DIV><SPAN class=e id=q_113febb8d1066932_1><BR><FONT
size=4>Shirley,<BR></FONT><BR><FONT size=4>On 7/25/07, </FONT><B><FONT
size=4>Shirley Ma</FONT></B><FONT size=4> <</FONT><A
onclick="return top.js.OpenExtLink(window,event,this)"
href="mailto:xma@us.ibm.com" target=_blank> <U><FONT color=#0000ff
size=4>xma@us.ibm.com</FONT></U></A><FONT size=4>> wrote: </FONT>
<UL><FONT size=4>Hello Hal,<BR><BR>How does openSM handle CAs with
different MTUs in the same subnet? For example, IPoIB broadcast group MTU,
IB multicast group PMTU? Does openSM pick up the smallest MTU in the
subnet? </FONT></UL><BR><FONT size=4></FONT><BR><FONT size=4>Are you asking
about link MTU, SA PathRecord/MultiPathRecord MTU, SA MCMemberRecord MTU, or
all of these ?</FONT><BR><FONT size=4></FONT><BR><FONT size=4>-- Hal
</FONT><BR>
<UL><FONT size=4>Thanks<BR>Shirley Ma</FONT></UL><BR>
<P></P></SPAN></DIV>
<P></P>
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