Obtaining Configuration Files - Cisco Catalyst 2950 Software Manual

Chapter 6 Configuring the System
Figure 6-2
DHCP server
For CLI procedures, refer to the Cisco IOS Release 12.1 documentation on Cisco.com for additional
information and CLI procedures.

Obtaining Configuration Files

Depending on the availability of the IP address and the configuration filename in the DHCP reserved
lease, the switch obtains its configuration information in these ways:
•
•
•
78-11380-03
Relay Device Used in Autoconfiguration
Switch
(DHCP client)
10.0.0.2
10.0.0.1
20.0.0.2 20.0.0.3
TFTP server
The IP address and the configuration filename is reserved for the switch and provided in the DHCP
reply (one-file read method).
The switch receives its IP address, subnet mask, and configuration filename from the DHCP server.
It also receives a DNS server IP address and a TFTP server name. The switch sends a DNS request
to the DNS server, specifying the TFTP server name, to obtain the TFTP server address. Then the
switch sends a unicast message to the TFTP server to retrieve the named configuration file from the
base directory of the server, and upon receipt, completes its boot-up process.
Only the configuration filename is reserved for the switch. The IP address is dynamically allocated
to the switch by the DHCP server (one-file read method).
The switch follows the same configuration process described in the first item.
Only the IP address is reserved for the switch and provided in the DHCP reply. The configuration
filename is not provided (two-file read method).
The switch receives its IP address and subnet mask from the DHCP server. It also receives a DNS
server IP address and a TFTP server name. The switch sends a DNS request to the DNS server,
specifying the TFTP server name, to obtain the TFTP server address.
The switch sends a unicast message to the TFTP server to retrieve the network-confg or cisconet.cfg
default configuration file. (If the network-confg file cannot be read, the switch reads the cisconet.cfg
file.)
The default configuration file contains the host names-to-IP-address mapping for the switch. The
switch fills its host table with the information in the file and obtains its host name. If the host name
is not found in the file, the switch uses the host name in the DHCP reply. If the host name is not
specified in the DHCP reply, the switch uses the default "Switch" as its host name.
Cisco router
(Relay)
20.0.0.1
20.0.0.4
DNS server
Catalyst 2950 Desktop Switch Software Configuration Guide
Changing IP Information
6-7