Administrator Guide

504 DHCP and USB Auto-Configuration
Obtaining IP Address Information
DHCP is enabled by default on the Out-of-Band (OOB) interface on Dell
Networking N3000 and N4000 Series switches. DHCP is enabled by default
on VLAN 1 on the Dell Networking N1500 and N2000 Series switches. If an
IP address has not been assigned, the switch issues requests for an IP address
assignment.
A network DHCP server returns the following information:
• IP address and subnet mask to be assigned to the interface
• IP address of a default gateway, if needed for IP communication
After an IP address is assigned to the switch, if a hostname is not already
assigned, Auto Configuration issues a DNS request for the corresponding
hostname. This hostname is also displayed as the CLI prompt (as in response
to the hostname command).
Obtaining Other Dynamic Information
The following information is also processed and may be returned by a
BOOTP or DHCP server:
• Name of configuration file (the file field in the DHCP header or option
67) to be downloaded from the TFTP server.
• Identification of the TFTP server providing the file. The TFTP server can
be identified by name or by IP address as follows:
– hostname: DHCP option 66 or the
sname field in the DHCP header)
– IP address: DHCP option 150 or the
siaddr field in the DHCP header
• NTP Server - Option 42
• SYSLOG Server - Option 7
• Client Host Name - Option 12
• Domain Name - Option 15
NOTE: The downloaded configuration file is not automatically saved to startup-
config. You must explicitly issue a save request (copy running-config startup-
config) in order to save the configuration. If the downloaded configuration is not
saved to the startup-config, DHCP auto configuration will be done every time the
DHCP lease expires.