option in the DHCP packet. Clients that do not include the client identifier option are identified by the client
hardware address. When you configure this feature, the port name of the interface overrides the client identifier
or hardware address and the actual point of connection, the switch port, becomes the client identifier.
In all cases, by connecting the Ethernet cable to the same port, the same IP address is allocated through DHCP
to the attached device.
The DHCP server port-based address allocation feature is only supported on a Cisco IOS DHCP server and
not a third-party server.
Default Port-Based Address Allocation Configuration
By default, DHCP server port-based address allocation is disabled.
Port-Based Address Allocation Configuration Guidelines
•
By default, DHCP server port-based address allocation is disabled.
•
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.
Enabling the DHCP Snooping Binding Database Agent
Beginning in privileged EXEC mode, follow these steps to enable and configure the DHCP snooping binding
database agent on the switch:
SUMMARY STEPS
1.
enable
2.
configure terminal
3.
ip dhcp snooping database
{
flash
[
number
]
:
/
filename
|
ftp://user:password@host/filename
|
http://
[[
username:password
]
@
]{
hostname | host-ip
}[/
directory
]
/image-name.tar
|
rcp://user@host/filename
}|
tftp://host/filename
4.
ip dhcp snooping database timeout seconds
5.
ip dhcp snooping database write-delay seconds
6.
end
7.
ip dhcp snooping binding mac-address vlan vlan-id ip-address interface interface-id expiry seconds
8.
show ip dhcp snooping database
[
detail
]
9.
show running-config
10.
copy running-config startup-config
Catalyst 2960-X Switch Security Configuration Guide, Cisco IOS Release 15.0(2)EX
OL-29048-01
227
Configuring DHCP
Default Port-Based Address Allocation Configuration