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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
OL-10101-02
Chapter 4 Assigning the Switch IP Address and Default Gateway
Assigning Switch Information
switchb-confg
switchc-confg
switchd-confg
prompt> cat network-confg
ip host switch1 10.0.0.21
ip host switch2 10.0.0.22
ip host switch3 10.0.0.23
ip host switch4 10.0.0.24
DHCP Client Configuration
No configuration file is present on Switch A through Switch D.
Configuration Explanation
In Figure 4-3, Switch A reads its configuration file as follows:
• It obtains its IP address 10.0.0.21 from the DHCP server.
• If no configuration filename is given in the DHCP server reply, Switch A reads the network-confg
file from the base directory of the TFTP server.
• It adds the contents of the network-confg file to its host table.
• It reads its host table by indexing its IP address 10.0.0.21 to its host name (switcha).
• It reads the configuration file that corresponds to its host name; for example, it reads switch1-confg
from the TFTP server.
Switches B through D retrieve their configuration files and IP addresses in the same way.
Understanding DHCP-Based Autoconfiguration with a Saved Configuration
DHCP-based autoconfiguration with a saved configuration works exactly the same as DHCP-based
autoconfiguration except that you can now enable an autoconfiguration on a switch that already contains
a basic configuration file in its memory.
To utilize DHCP-based autoconfiguration with a saved configuration, you will need to pre-configure a
switch with a basic booting configuration and deploy the switch in your network. That pre-configuration
should include the necessary Layer 3 interfacefor obtaining an IP address and the configuration file. The
Layer 3 interface must have a specific DHCP scope configured on the DHCP server which includes
option 150 TFTP server IP address and option 67 Configuration filename. After you install the switch in
to your network, if it is enabled, the auto-install feature will start. The downloaded configuration file is
saved in the running configuration of the switch. The configuration file is not saved in NVRAM. When
the switch is restarted the downloaded configuration is ignored and a fresh configuration is downloaded
from the TFTP server.

Limitations and Restrictions

• The DHCP-based autoconfiguration with a saved configuration process is aborted if there is not at
least one Layer 3 interface in an up state without an assigned IP address in the network.
• Unless you configure a time-out the DHCP-based autoconfiguration with a saved configuration
feature will try indefinitely to download an IP address.
• The auto-install process is aborted if a configuration file cannot be downloaded or the configuration
file is corrupted.