Technical Product Specification

Intel® Server Boards S4600LH2/T2 TPS
Revision 2.0
76
6.10.3.5.3 Enabling/Disabling Dynamic Host Configuration (DHCP) Protocol
The BMC DHCP feature is activated by using the Set LAN Configuration Parameter command to set LAN
configuration parameter 4, IP Address Source, to 2h: “address obtained by BMC running DHCP”. Once this
parameter is set, the BMC initiates the DHCP process within approximately 100 ms.
If the BMC has previously been assigned an IP address through DHCP or the Set LAN Configuration
Parameter command, it requests that same IP address to be reassigned. If the BMC does not receive the
same IP address, system management software must be reconfigured to use the new IP address. The new
address is only available in-band, through the IPMI Get LAN Configuration Parameters command.
Changing the IP Address Source parameter from 2h to any other supported value will cause the BMC to stop
the DHCP process. The BMC uses the most recently obtained IP address until it is reconfigured.
If the physical LAN connection is lost (that is, the cable is unplugged), the BMC will not re-initiate the DHCP
process when the connection is re-established.
6.10.3.5.4 DHCP-related LAN Configuration Parameters
Users may not change the following LAN parameters while the DHCP is enabled:
 LAN configuration parameter 3 (IP Address)
 LAN configuration parameter 6 (Subnet Mask)
 LAN configuration parameter 12 (Default Gateway Address)
To prevent users from disrupting the BMC’s LAN configuration, the BMC treats these parameters as read-only
while DHCP is enabled for the associated LAN channel. Using the Set LAN Configuration Parameter command
to attempt to change one of these parameters under such circumstances has no effect, and the BMC returns
error code 0xD5, “Cannot Execute Command. Command, or request parameter(s) are not supported in present
state.”
6.10.3.6 DHCP BMC Hostname
The BMC allows setting a DHCP Hostname using the Set/Get LAN Configuration Parameters command.
 DHCP Hostname can be set regardless of the IP Address source configured on the BMC. But this
parameter is only used if the IP Address source is set to DHCP.
 When Byte 2 is set to “Update in progress”, all the 16 Block Data Bytes (Bytes 3 – 18) must be present in
the request.
 When Block Size < 16, it must be the last Block request in this series. In other words Byte 2 is equal to
“Update is complete” on that request.
 Whenever Block Size < 16, the Block data bytes must end with a NULL Character or Byte (=0).
 All Block write requests are updated into a local Memory byte array. When Byte 2 is set to “Update is
Complete”, the Local Memory is committed to the NV Storage. Local Memory is reset to NULL after
changes are committed.
 When Byte 1 (Block Selector = 1), firmware resets all the 64 bytes local memory. This can be used to
undo any changes after the last “Update in Progress”.
 User should always set the hostname starting from block selector 1 after the last “Update is complete”. If
the user skips block selector 1 while setting the hostname, the BMC will record the hostname as “NULL,”
because the first block contains NULL data.
 This scheme effectively does not allow a user to make a partial Hostname change. Any Hostname
change needs to start from Block 1.
 Byte 64 ( Block Selector 04h byte 16) is always ignored and set to NULL by BMC which effectively means
we can set only 63 bytes.
 User is responsible for keeping track of the Set series of commands and Local Memory contents.
While BMC firmware is in “Set Hostname in Progress” (Update not complete), the firmware continues using the
Previous Hostname for DHCP purposes.