[Freeipmi-devel] Re: [llnl-devel] Multiple Mac Addresses

[Anand Babu]

Ethernet controller is just one. BMC hooks into the controller to tap
IPMI RMCP/UDP packets. 

Host and the BMC can have different IP addresses, but the MAC
address should always be same as that of the Ethernet controller.

IP address settings are currently configured as "static". Problem can
also be caused because of faulty negotiation between the switch and
the NIC. 

-ab
,----[ address@hidden ]
|     I'm betting that there are two ethernet chips and in the "normal"
|     configuration the BMC sets the MAC address of the BMC's ethernet
|     controller to the same MAC address as the host's controller. Then
|     during the shutdown procedure in the driver for the main hosts
|     ethernet controller, it reconfigures the ethernet controller to
|     some default state. This causes the BMC's ethernet controller to
|     switch its MAC address to that same state and so consequently it
|     doesn't have the right MAC address and so the switch gets
|     confused.
| 
| OK, I bet a nickel.  ;-)
| 
| AFAIK the BMC's configuration is static.  There is some default MAC
| and IP address out of the box, but once we set the BMC's MAC and IP to
| match the node's eth0 settings, it should stay that way forever.
| There is no dynamic relationship that is maintained between the BMC
| and eth0.  Nor is there anything inherent in the design of the BMC
| that even requires it to have the same MAC and IP address as eth0.  We
| set them that way for convenience.
| 
| -Robin
`----

-- 
Anand Babu
Free as in Freedom <www.gnu.org>