ipmi_si on PE650 (Debian stock kernel)

Brian A. Seklecki bseklecki at collaborativefusion.com
Mon Apr 23 13:32:30 CDT 2007

On Mon, 2007-04-23 at 13:11 -0500, Matt Domsch wrote:
> On Mon, Apr 23, 2007 at 11:53:57AM -0400, Brian A. Seklecki wrote:
> > One really shouldn't need in-kernel IPMI support since the IPMI is
> > loaded into the BMC which ARP's at a different L4IP address.
> > 
> > Kernel IPMI would be what? A pass-through to the same data at a separate
> > address (perhaps the management address of the system)?  Or, a
> > completely different set of SDR data related that which the Kernel can
> > see but not the BMC (like RAID).
> Yes, it lets you communicate "in-band" with the BMC without going over
> the network and back to your local machine. 

Right which makes sense if you're wanting to monitor your monitoring
machine, but communicating with the BMC seems generally like the sole
responsibility of a dedicated monitoring machine.  Maybe in
non-enterprise networks, systems tend to monitor themselves, but that's
a minority case elsewhere.

>  In fact you can't
> communicate with your local machine's BMC from local machine's network 
> port if it's sharing the same physical RJ45 jack.

I've always wondered if that's because the NIC driver in the OS/Kernel
refuses to acknowledge or process "ingress" Ethernet packets with a
source MAC address matching the link-local MAC address of the receiver,
but also having a foreign IP address not known locally.

That's assuming the IPMI BMC uses the MAC address of the ethernet port
it shares.

Its really creepy when the BMC transmits IMPI packets out of a shared
interface, it appears in the transmit buffer and the operating system
can see it via tcpdump(8); it even increments the netstat(8) counters.

At least that was my assumption for a long time.  Recently we've been
under the impression that it's a driver bug:



> Thanks,
> Matt
Brian A. Seklecki <bseklecki at collaborativefusion.com>
Collaborative Fusion, Inc.

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