Purpose Of The Tftp Server; Purpose Of The Dns Server; How To Obtain Configuration Files - Cisco Catalyst 9500 Manual

Performing Device Setup Configuration

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 device. Normally,
If you specify the TFTP server name in the DHCP server-lease database, you must also configure the TFTP
server name-to-IP-address mapping in the DNS-server database.
If the TFTP server to be used is on a different LAN from the device, or if it is to be accessed by the device
through the broadcast address (which occurs if the DHCP server response does not contain all the required
information described previously), a relay must be configured to forward the TFTP packets to the TFTP server.
The preferred solution is to configure the DHCP server with all the required information.

Purpose of the DNS Server

The DHCP server uses the DNS server to resolve the TFTP server name to an IP address. You must configure
the TFTP server name-to-IP address map on the DNS server. The TFTP server contains the configuration
files for the device.
You can configure the IP addresses of the DNS servers in the lease database of the DHCP server from where
the DHCP replies will retrieve them. You can enter up to two DNS server IP addresses in the lease database.
The DNS server can be on the same LAN or on a different LAN from the device. If it is on a different LAN,
the device must be able to access it through a router.

How to Obtain Configuration Files

Depending on the availability of the IP address and the configuration filename in the DHCP reserved lease,
the device obtains its configuration information in these ways:
• The IP address and the configuration filename is reserved for the device and provided in the DHCP reply
if the DHCP and TFTP servers are properly configured, these files are not accessed.)
(one-file read method).
The device receives its IP address, subnet mask, TFTP server address, and the configuration filename
from the DHCP server. The device sends a unicast message to the TFTP server to retrieve the named
configuration file from the base directory of the server and upon receipt, it completes its boot up process.
System Management Configuration Guide, Cisco IOS XE Amsterdam 17.2.x (Catalyst 9500 Switches)
Purpose of the TFTP Server
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