The Usb Discovery Phase; The Dhcp Discovery Phase; Using Poweron Auto Provisioning - Cisco MDS 9000 Series Configuration Manual

The POAP Process
If you exit the POAP mode, you enter a script. If you continue in the POAP mode, all the front-panel interfaces
are set up in the default configuration.

The USB Discovery Phase

When the POAP process begins, the switch searches the root directory for the presence of accessible USB
devices with the POAP configuration script file (poap_script.tcl), configuration files, and system and kickstart
images.
If the configuration script file is found on a USB device, POAP begins to run the configuration script. If the
configuration script file is not found on the USB device, POAP executes DHCP discovery. (When failures
occur, the POAP process alternates between USB discovery and DHCP discovery until POAP succeeds or
you manually abort the POAP process.)
If the software image and switch configuration files specified in the configuration script are present, POAP
uses those files to install the software and configure the switch. If the software image and switch configuration
files are not on the USB device, POAP performs a clean-up operation and starts the DHCP phase from the
beginning.

The DHCP Discovery Phase

The switch sends out DHCP discover messages on the management interface that solicits DHCP offers from
the DHCP server or servers. (See the following
client on the Cisco MDS switch uses the switch serial number in the client-identifier option to identify itself
to the DHCP server. The DHCP server can use this identifier to send information, such as the IP address and
script filename, back to the DHCP client.
The POAP process requires a minimum DHCP lease period of 3600 seconds (1 hour). POAP checks the DHCP
lease period. If the DHCP lease period is set to less than 3600 seconds (1 hour), POAP does not complete
DHCP negotiation, but enters the USB phase.
The POAP process has to be aborted manually.
Note
The DHCP discover message also solicits the following options from the DHCP server:
• TFTP server name or TFTP server address—The DHCP server relays the TFTP server name or TFTP
server address to the DHCP client, which uses this information to contact the TFTP server to obtain the
script file.
• Bootfile name—The DHCP server relays the bootfile name to the DHCP client. The bootfile name
includes the complete path to the bootfile on the TFTP server. The DHCP client uses this information
to download the script file.
When multiple DHCP offers that meet the requirement are received, an offer is randomly chosen. The device
completes the DHCP negotiation (request and acknowledgment) with the selected DHCP server, and the
DHCP server assigns an IP address to the switch. If a failure occurs in any of the subsequent steps in the
POAP process, the IP address is released back to the DHCP server.
Cisco MDS 9000 Family NX-OS Fundamentals Configuration Guide
34
Figure 6: DHCP Discovery Process, on page

Using PowerOn Auto Provisioning

35.) The DHCP
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