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<p>PICMG has defined certain specifications in this angle (HPM), but
those basically uses IPMI (PICMG group extension commands)<br>
</p>
<p>1. Physical interface (i2c/IPMB) - IPMI</p>
<p>2. LAN Channel - IPMI RMCP+ other Direct stuff for say console
access etc.<br>
</p>
<p>PICMG started working with DMTF redfish for the purpose of IPMC
to IPMC communication few years before (but not sure where it
stands now)<br>
</p>
<p>No one solution will fit for all, and need to consider based on
1. Features required (ssh / serial console access / SOL / KVM
etc.) and 2. Physical interface between the controller (I2C/ LAN /
others?) . Nancy / Vijay??<br>
</p>
<p>Say, with i2c- anything related to SSH / KVM forwarding etc is
going to be a problem, but with LAN these can be addressed.<br>
</p>
<p>With i2c-> IPMB / PLDM (MCTP over smbus) (with IPMI moving
out of picture PLDM will be better alternative).</p>
<p>With LAN -> PLDM / Redfish. (Using Redfish has advantage over
PLDM for RDE, and still other features can be supported)<br>
</p>
<p>Apart from this, need to define fail-over management(PICMG
defined some) / discovery(MCTP offers some) etc.<br>
</p>
<p>Regards,</p>
<p>Richard<br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 5/8/2020 10:48 PM, Vijay Khemka
wrote:<br>
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<p class="MsoNormal"><b><span
style="font-size:12.0pt;color:black">From: </span></b><span
style="font-size:12.0pt;color:black">openbmc
<a class="moz-txt-link-rfc2396E" href="mailto:openbmc-bounces+vijaykhemka=fb.com@lists.ozlabs.org"><openbmc-bounces+vijaykhemka=fb.com@lists.ozlabs.org></a>
on behalf of Nancy Yuen <a class="moz-txt-link-rfc2396E" href="mailto:yuenn@google.com"><yuenn@google.com></a><br>
<b>Date: </b>Thursday, May 7, 2020 at 12:47 PM<br>
<b>To: </b>Andrew Jeffery <a class="moz-txt-link-rfc2396E" href="mailto:andrew@aj.id.au"><andrew@aj.id.au></a><br>
<b>Cc: </b>OpenBMC Maillist
<a class="moz-txt-link-rfc2396E" href="mailto:openbmc@lists.ozlabs.org"><openbmc@lists.ozlabs.org></a><br>
<b>Subject: </b>Re: Multiple BMCs in a system: IPMB?
Redfish? MCTP?<o:p></o:p></span></p>
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<p class="MsoNormal">On Mon, May 4, 2020 at 3:31 AM Andrew
Jeffery <<a href="mailto:andrew@aj.id.au"
moz-do-not-send="true">andrew@aj.id.au</a>> wrote:<o:p></o:p></p>
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<br>
On Thu, 30 Apr 2020, at 17:08, Deepak Kodihalli wrote:<br>
> On 30/04/20 4:21 am, Nancy Yuen wrote:<br>
> > I've talked with some people a while back
(long while back) about <br>
> > multiple BMCs in a system. Either for
redundancy or managing separate <br>
> > parts of a system. I'm wondering what other
people are thinking in <br>
> > this area if at all.<br>
> > <br>
> > We are considering similar designs and I'm
looking into options for <br>
> > BMC-BMC communications. Some BMCs may not be
externally <br>
> > accessible. Here are some options that we've
looked at:<br>
> > <br>
> > 1. i2c/IPMB<br>
> > 2. usbnet/Redfish<br>
> > 3. i2c/MCTP/PLDM or something else?<br>
> > 4. internal network via switch chip/Redfish
or MCTP<br>
> > <br>
> > I'd like to reduce our use of IPMI so I want
to avoid (1).<br>
> > <br>
> > ----------<br>
> > Nancy<br>
> <br>
> Hi Nancy,<br>
> <br>
> I think it depends on whether the BMCs need to talk
to each other for <br>
> platform management, or if they manage their own
hosts and we need one <br>
> of the BMCs to broadcast out of band requests and
aggregate responses.<br>
> <br>
> For the former I think PLDM over MCTP could be a
good fit. This is more <br>
> of an "inband" use-case in my opinion so I'm not
sure if Redfish is well <br>
> suited. For the latter, a Redfish based aggregation
is a good option.<br>
<br>
I think this looks like the right approach. Certainly
some thought would be<br>
required in designing the MCTP networks given the
(intentionally) limited<br>
number of endpoint IDs.<br>
<br>
Andrew<o:p></o:p></p>
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<p class="MsoNormal">Hi Andrew, Deepak,<o:p></o:p></p>
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<p class="MsoNormal">Sorry for the delayed response!<o:p></o:p></p>
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<p class="MsoNormal">For the purposes of this discussion I
have BMCs managing their own host:
BMC3<--->BMC2<--->BMC1/controller<-->
external. I wrote BMC1 but there maybe some other
controller there that isn't strictly a BMC. BMC2 would
be "passing through" information between BMC1 and BMC3.
But I don't necessarily want BMC2 to do any form of
aggregation from information from BMC3. For
BMC1/Controller and BMC 2 we are thinking Redfish. <o:p></o:p></p>
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<p class="MsoNormal">In my case I'm interested in what
ways people are thinking BMC2 and BMC3 should be
connected and speaking to each other. Is MCTP/PLDM where
everyone is leaning?<o:p></o:p></p>
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<p class="MsoNormal">Nancy,<o:p></o:p></p>
<p class="MsoNormal">What is connectivity between BMC1,
BMC2 and BMC3. Are these exposing any out of band
connections. For security reasons, aggregator should use
inband connectivity between BMCs and as Deepak said MCTP
is good option for inband.<o:p></o:p></p>
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