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After a specified number of consecutive attempts (automatic or manual), the Nx boot failure feature causes
the server to revert to the default UEFI configuration and start the Setup utility so that you can make the
necessary corrections to the configuration and restart the server. If the server is unable to successfully
complete POST with the default configuration, there might be a problem with the system board.
To specify the number of consecutive restart attempts that will trigger the Nx boot failure feature, complete
the following steps:
Step 1.
In the Setup utility, click System Settings ➙ Operating Modes ➙ POST Attempts Limit.
Step 2.
The available options are 3, 6, 9, and 255 (disable Nx boot failure). Select your option.
Accessing the IMM
Unlike a baseboard management controller, the IMM does not require IPMI device drivers or USB daemons
for in-band IMM communication. Instead, a LAN over USB interface enables in-band communications to the
IMM; the IMM hardware on the system board presents an internal Ethernet interface from the IMM to the
operating system. LAN over USB is also called the USB in-band interface in the IMM web interface.
In a scalable blade complex, each IMM is shown as a LAN over USB device in the operating system. For
each blade server in the scalable blade complex to be a unique and known IP address, both blade servers
have different default IP addresses. The default IP address for the primary blade server is 169.254.95.118,
and the Keyboard Controller Style (KCS) address is 0x6CA8.
For packets to be routed correctly from the host to the IMMs, each of the LAN over USB interfaces must
appear on a separate subnet to the host. The IMM implements a DHCP server that services only the LAN
over USB interface. It assigns the subnet mask on the LAN over USB interfaces for the host to
255.255.255.0.
The following table shows the IP addresses for each of the blade servers in a complex.
Table 3. LAN over USB addresses
Logi-
cal
Blade
node
IMM IP
server
ID
address
Primary
0
169.265.95.-
118
1
169.265.96.-
Secon-
dary
118
LAN over USB devices are not aware of LAN over USB devices in other partitions. If you configure the two
blade servers as two independent partitions in a scalable blade complex, each blade server is considered to
the primary blade server of the hardware partition that contains that blade server. The logical ID of the
primary in each partition is 0 and the default IP address of each primary blade server is 169.254.95.118.
Potential conflicts with the LAN over USB interface
In some situations, the IMM LAN over USB interface can conflict with certain network configurations,
applications, or both.
For example, Open MPI (Message Passing Interface) attempts to use all the available network interfaces on a
server. Open MPI detects the IMM LAN over USB interface and attempts to use it to communicate with other
systems in a clustered environment. The LAN over USB interface is an internal interface, so this interface
does not work for external communication with other systems in the cluster.
Host
address
Host subnet
169.254.95.-
169.254.95.0/
120
24
169.254.96.-
169.254.96.0/
120
24
Keyboard Controller
Host subnet
Style (KCS) address
mask
255.255.255.0
0x8CA6
255.255.255.0
0x8CA8
.
Chapter 2
Configuring the blade server
53
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