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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-21521-01
Chapter 24 Configuring DHCP Features and IP Source Guard
Configuring DHCP Server Port-Based Address Allocation
To disable DHCP port-based address allocation, use the no ip dhcp use subscriber-id client-id global
configuration command. To disable the automatic generation of a subscriber identifier, use the no ip
dhcp subscriber-id interface-name global configuration command. To disable the subscriber identifier
on an interface, use the no ip dhcp server use subscriber-id client-id interface configuration command.
To remove an IP address reservation from a DHCP pool, use the no addr
ess ip-address client-id string
DHCP pool configuration command. To change the address pool to nonrestricted, enter the no
reserved-only DHCP pool configuration command.
In this example, a subscriber ident
ifier is automatically generated, and the DHCP server ignores any
client identifier fields in the DHCP messages and uses the subscriber identifier instead. The subscriber
identifier is based on the short name of the interface and the client preassigned IP address 10.1.1.7.
switch# show running config
Building configuration...
Current configuration : 4899 bytes
!
version 12.2
!
hostname switch
!
no aaa new-model
clock timezone EST 0
ip subnet-zero
ip dhcp relay information policy removal pad
no ip dhcp use vrf connected
ip dhcp use subscriber-id client-id
ip dhcp subscriber-id interface-name
ip dhcp excluded-address 10.1.1.1 10.1.1.3
!
ip dhcp pool dhcppool
network 10.1.1.0 255.255.255.0
address 10.1.1.7 client-id “Et1/0” ascii
<output truncated>
This example shows that the preassigned address was correctly reserved in the DHCP pool:
switch# show ip dhcp pool dhcppool
Pool dhcp pool:
Utilization mark (high/low) : 100 / 0
Subnet size (first/next) : 0 / 0
Total addresses : 254
Leased addresses : 0
Excluded addresses : 4
Pending event : none
1 subnet is currently in the pool:
Current index IP address range Leased/Excluded/Total
10.1.1.1 10.1.1.1 - 10.1.1.254 0 / 4 / 254
1 reserved address is currently in the pool
Address Client
10.1.1.7 Et1/0
Step 5
reserved-only (Optional) Use only reserved addresses in the DHCP
address pool. The default is to not restrict pool
addresses.
Step 6
end Return to privileged EXEC mode.
Step 7
show ip dhcp pool Verify DHCP pool configuration.
Step 8
copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose