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Catalyst 2928 Switch Software Configuration Guide
OL-23389-01
Chapter 19 Configuring DHCP Features and IP Source Guard Features
Configuring DHCP Server Port-Based Address Allocation
Enabling DHCP Server Port-Based Address Allocation
Beginning in privileged EXEC mode, follow these steps to globally enable port-based address allocation
and to automatically generate a subscriber identifier on an interface.
After enabling DHCP port-based address allocation on the switch, use the
ip dhcp pool
global
configuration command to preassign IP addresses and to associate them to clients. To restrict
assignments from the DHCP pool to preconfigured reservations, you can enter the
reserved-only
DHCP
pool configuration command. Unreserved addresses that are part of the network or on pool ranges are
not offered to the client, and other clients are not served by the pool. By entering this command, users
can configure a group of switches with DHCP pools that share a common IP subnet and that ignore
requests from clients of other switches.
Beginning in privileged EXEC mode follow these steps to preassign an IP address and to associate it to
a client identified by the interface name.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
ip dhcp use subscriber-id client-id
Configure the DHCP server to globally use the
subscriber identifier as the client identifier on all
incoming DHCP messages.
Step 3
ip dhcp subscriber-id interface-name
Automatically generate a subscriber identifier based
on the short name of the interface.
A subscriber identifier configured on a specific
interface takes precedence over this command.
Step 4
interface
interface-id
Specify the interface to be configured, and enter
interface configuration mode.
Step 5
ip dhcp server use subscriber-id client-id
Configure the DHCP server to use the subscriber
identifier as the client identifier on all incoming
DHCP messages on the interface.
Step 6
end
Return to privileged EXEC mode.
Step 7
show running config
Verify your entries.
Step 8
copy running-config startup-config
(Optional) Save your entries in the configuration file.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
ip dhcp pool
poolname
Enter DHCP pool configuration mode, and define the
name for the DHCP pool. The pool name can be a
symbolic string (such as Engineering) or an integer
(such as 0).
Step 3
network
network-number
[
mask
|
/prefix-length
]
Specify the subnet network number and mask of the
DHCP address pool.
Step 4
address
ip-address
client-id
string
[
ascii
]
Reserve an IP address for a DHCP client identified by
the interface name.
string
—can be an ASCII value or a hexadecimal
value.
