Administrator Guide

DHCP Client
An Aggregator is auto-configured to operate as a DHCP client. The DHCP client functionality is enabled only
on the default VLAN and the management interface.
A DHCP client is a network device that requests an IP address and configuration parameters from a DHCP
server. On an Aggregator, the DHCP client functionality is implemented as follows:
• The public out-of-band management (OOB) interface and default VLAN 1 are configured, by default, as
a DHCP client to acquire a dynamic IP address from a DHCP server.
You can override the DHCP-assigned address on the OOB management interface by manually
configuring an IP address using the CLI or CMC interface. If no user-configured IP address exists for the
OOB interface exists and if the OOB IP address is not in the startup configuration, the Aggregator will
automatically obtain it using DHCP.
You can also manually configure an IP address for the VLAN 1 default management interface using the
CLI. If no user-configured IP address exists for the default VLAN management interface exists and if the
default VLAN IP address is not in the startup configuration, the Aggregator will automatically obtain it
using DHCP.
• The default VLAN 1 with all ports configured as members is the only L3 interface on the Aggregator.
When the default management VLAN has a DHCP-assigned address and you reconfigure the default
VLAN ID number, the Aggregator:
• Sends a DHCP release to the DHCP server to release the IP address.
• Sends a DHCP request to obtain a new IP address. The IP address assigned by the DHCP server is
used for the new default management VLAN.
How DHCP Client is Implemented
The Aggregator is enabled by default to receive DHCP server-assigned dynamic IP addresses on an interface.
This setting persists after a switch reboot. If you enter the shutdown command on the interface, DHCP
transactions are stopped and the dynamically-acquired IP address is saved. Use the
show interface type
slot/port command to display the dynamic IP address and DHCP as the mode of IP address assignment. If
you later enter the no shutdown command and the lease timer for the dynamic IP address has expired, the
IP address is unconfigured and the interface tries to acquire a new dynamic address from DHCP server.
If you later enter the no shutdown command and the lease timer for the dynamic IP address has expired, the
IP address is released.
When you enter the release dhcp command, although the IP address that was dynamically-acquired from
a DHCP server is released from an interface, the ability to acquire a new DHCP server-assigned address
remains in the running configuration for the interface. To acquire a new IP address, enter either the renew
dhcp
command at the EXEC privilege level or the ip address dhcp command at the interface
configuration level.
If you enter renew dhcp command on an interface already configured with a dynamic IP address, the lease
time of the dynamically acquired IP address is renewed.
Dynamic Host Configuration Protocol (DHCP) 317