• If you want the device to receive IP address information, you must configure the DHCP server with these
lease options:
• IP address of the client (required)
• Subnet mask of the client (required)
• DNS server IP address (optional)
• Router IP address (default gateway address to be used by the device) (required)
• If you want the device to receive the configuration file from a TFTP server, you must configure the
DHCP server with these lease options:
• TFTP server name (required)
• Boot filename (the name of the configuration file that the client needs) (recommended)
• Hostname (optional)
• Depending on the settings of the DHCP server, the device can receive IP address information, the
configuration file, or both.
• If you do not configure the DHCP server with the lease options described previously, it replies to client
requests with only those parameters that are configured. If the IP address and the subnet mask are not in
the reply, the device is not configured. If the router IP address or the TFTP server name are not found,
the device might send broadcast, instead of unicast, TFTP requests. Unavailability of other lease options
does not affect autoconfiguration.
• The device can act as a DHCP server. By default, the Cisco IOS DHCP server and relay agent features
are enabled on your device but are not configured. (These features are not operational.)
Purpose of the TFTP Server
Based on the DHCP server configuration, the device attempts to download one or more configuration files
from the TFTP server. If you configured the DHCP server to respond to the device with all the options required
for IP connectivity to the TFTP server, and if you configured the DHCP server with a TFTP server name,
address, and configuration filename, the device attempts to download the specified configuration file from
the specified TFTP server.
If you did not specify the configuration filename, the TFTP server, or if the configuration file could not be
downloaded, the device attempts to download a configuration file by using various combinations of filenames
and TFTP server addresses. The files include the specified configuration filename (if any) and these files:
network-config, cisconet.cfg,
hostname
.config, or
hostname
.cfg, where
hostname
is the device’s current
hostname. The TFTP server addresses used include the specified TFTP server address (if any) and the broadcast
address (255.255.255.255).
For the device to successfully download a configuration file, the TFTP server must contain one or more
configuration files in its base directory. The files can include these files:
• The configuration file named in the DHCP reply (the actual device configuration file).
• The network-confg or the cisconet.cfg file (known as the default configuration files).
• The router-confg or the ciscortr.cfg file (These files contain commands common to all devices. Normally,
if the DHCP and TFTP servers are properly configured, these files are not accessed.)
System Management Configuration Guide, Cisco IOS XE Gibraltar 16.10.x (Catalyst 9200 Switches)
57
Performing Device Setup Configuration
Purpose of the TFTP Server