Enabling Dhcp Server Port-Based Address Allocation - Cisco Catalyst 2975 Software Configuration Manual

Configuring DHCP Server Port-Based Address Allocation
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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.
Command
Step 1
configure terminal
Step 2 ip dhcp use subscriber-id client-id
Step 3
ip dhcp subscriber-id interface-name
Step 4
interface interface-id
Step 5 ip dhcp server use subscriber-id client-id
Step 6
end
Step 7 show running config
Step 8 copy running-config startup-config
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.
Catalyst 2975 Switch Software Configuration Guide
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Preassigned addresses are automatically excluded from normal dynamic IP address assignment.
Preassigned addresses cannot be used in host pools, but there can be multiple preassigned addresses
per DHCP address pool.
To restrict assignments from the DHCP pool to preconfigured reservations (unreserved addresses
are not offered to the client and other clients are not served by the pool), you can enter the
reserved-only DHCP pool configuration command.
Chapter 20 Configuring DHCP Features and IP Source Guard Features
Purpose
Enter global configuration mode.
Configure the DHCP server to globally use the
subscriber identifier as the client identifier on all
incoming DHCP messages.
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.
Specify the interface to be configured, and enter
interface configuration mode.
Configure the DHCP server to use the subscriber
identifier as the client identifier on all incoming
DHCP messages on the interface.
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
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