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Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
 
Chapter 3      Configuring the Switch for the First Time
Configuring DHCP-Based Autoconfiguration
Configuring DHCP-Based Autoconfiguration
These sections describe how to configure DHCP-based autoconfiguration:
• About DHCP-Based Autoconfiguration, page 3-2
• DHCP Client Request Process, page 3-3
• Configuring the DHCP Server, page 3-4
• Configuring the TFTP Server, page 3-4
• Configuring the DNS Server, page 3-5
• Configuring the Relay Device, page 3-5
• Obtaining Configuration Files, page 3-6
• Example Configuration, page 3-7
If your DHCP server is a Cisco device, or if you are configuring the switch as a DHCP server, refer to 
the “IP Addressing and Services” section in the Cisco IOS IP and IP Routing Configuration Guide for 
Cisco IOS Release 12.1 for additional information about configuring DHCP.
About DHCP-Based Autoconfiguration
Note Beginning with Release 12.2(20)EW, you can enable DHCP AutoConfiguration by entering the write 
erase command. This command clears the startup-config in NVRAM. In images prior to Release 
12.2(20)EW, this command does not enable autoconfiguration.
DHCP provides configuration information to Internet hosts and internetworking devices. This protocol 
consists of two components: one component for delivering configuration parameters from a DHCP 
server to a device and another component that is a mechanism for allocating network addresses to 
devices. DHCP is built on a client-server model, in which designated DHCP servers allocate network 
addresses and deliver configuration parameters to dynamically configured devices. The switch can act 
as both a DHCP client and a DHCP server.
With DHCP-based autoconfiguration, no DHCP client-side configuration is needed on your switch 
because your switch (the DHCP client) is automatically configured at startup with IP address 
information and a configuration file. However, you need to configure the DHCP server or the DHCP 
server feature on your switch for various lease options associated with IP addresses. If you are using 
DHCP to relay the configuration file location on the network, you might also need to configure a Trivial 
File Transfer Protocol (TFTP) server and a Domain Name System (DNS) server.
DHCP-based autoconfiguration replaces the BOOTP client functionality on your switch.
Passwords No passwords are configured for normal mode or enable mode 
(press the Return key) 
Switch prompt
Switch> 
Interfaces Enabled, with speed and flow control autonegotiated, and without 
IP addresses
Table 3-1 Default Switch Configuration (continued)
Feature Default Settings