Users 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)