Power-Up Phase; Dhcp Discovery Phase - Cisco Nexus 9000 Series Configuration Manual

Using PowerOn Auto Provisioning

Power-Up Phase

When you powerup the device for the first time, it loads the software image that is installed at manufacturing
and tries to find a configuration file from which to boot. When a configuration file is not found, POAP mode
starts.
During startup, a prompt appears asking if you want to abort POAP and continue with a normal setup. You
can choose to exit or continue with POAP.
No user intervention is required for POAP to continue. The prompt that asks if you want to abort POAP
Note
remains available until the POAP process is complete.
If you exit POAP mode, you enter the normal interactive setup script. If you continue in POAP mode, all the
front-panel interfaces are set up in the default configuration.

DHCP Discovery Phase

The switch sends out DHCP discover messages on the front-panel interfaces or the MGMT interface that
solicit DHCP offers from the DHCP server or servers. (See the following figure.) The DHCP client on the
Cisco Nexus 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.
POAP 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 the DHCP
negotiation.
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. The DHCP client 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 Nexus 9000 Series NX-OS Fundamentals Configuration Guide, Release 7.x
POAP Process
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