<html xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
/* List Definitions */
@list l0
{mso-list-id:1308702607;
mso-list-template-ids:1474038348;}
ol
{margin-bottom:0in;}
ul
{margin-bottom:0in;}
--></style>
</head>
<body lang="EN-US" link="blue" vlink="purple">
<div class="WordSection1">
<p class="MsoNormal">Nancy,<o:p></o:p></p>
<p class="MsoNormal">We have multiple hosts which has a small controller called BIC (Bridge IC). This BIC on each host connected via i2c to main BMC and communicates through ipmi messages to BMC over IPMB/i2c.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Regards<o:p></o:p></p>
<p class="MsoNormal">-Vijay<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="font-size:12.0pt;color:black">From: </span></b><span style="font-size:12.0pt;color:black">Nancy Yuen <yuenn@google.com><br>
<b>Date: </b>Wednesday, April 29, 2020 at 5:25 PM<br>
<b>To: </b>Vijay Khemka <vijaykhemka@fb.com><br>
<b>Cc: </b>OpenBMC Maillist <openbmc@lists.ozlabs.org><br>
<b>Subject: </b>Re: Multiple BMCs in a system: IPMB? Redfish? MCTP?<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Neeraj, I was not considering aggregation in this case, just having the intermediate BMC "route".
<o:p></o:p></p>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Vijay, thanks. I was wondering what your applications for IPMB were for. What's the rationale for using IPMB vs something else? In your multihost system, one BMC supports multiple host CPUs? Are there also multiple BMCs?<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><br clear="all">
<o:p></o:p></p>
<div>
<div>
<p class="MsoNormal">----------<br>
Nancy<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal">On Wed, Apr 29, 2020 at 5:15 PM Vijay Khemka <<a href="mailto:vijaykhemka@fb.com" target="_blank">vijaykhemka@fb.com</a>> wrote:<o:p></o:p></p>
</div>
<blockquote style="border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in">
<div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hi Nancy,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">We are currently using (1) in our current multi host design. Option (3) also looks good.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Regards<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">-Vijay<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">openbmc <openbmc-bounces+vijaykhemka=<a href="mailto:fb.com@lists.ozlabs.org" target="_blank">fb.com@lists.ozlabs.org</a>> on behalf of Nancy Yuen <<a href="mailto:yuenn@google.com" target="_blank">yuenn@google.com</a>><br>
<b>Date: </b>Wednesday, April 29, 2020 at 3:53 PM<br>
<b>To: </b>OpenBMC Maillist <<a href="mailto:openbmc@lists.ozlabs.org" target="_blank">openbmc@lists.ozlabs.org</a>><br>
<b>Subject: </b>Multiple BMCs in a system: IPMB? Redfish? MCTP?</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
</div>
<div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I've talked with some people a while back (long while back) about multiple BMCs in a system. Either for redundancy or managing separate parts of a system. I'm wondering what
other people are thinking in this area if at all.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">We are considering similar designs and I'm looking into options for BMC-BMC communications. Some BMCs may not be externally accessible. Here are some options that we've looked
at:<o:p></o:p></p>
</div>
<div>
<ol start="1" type="1">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
i2c/IPMB<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
usbnet/Redfish<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
i2c/MCTP/PLDM or something else?<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
internal network via switch chip/Redfish or MCTP<o:p></o:p></li></ol>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> I'd like to reduce our use of IPMI so I want to avoid (1).<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">----------<br>
Nancy<o:p></o:p></p>
</div>
</div>
</div>
</div>
</blockquote>
</div>
</div>
</body>
</html>