Cisco Catalyst 2960 Series, Configuration Manual

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Enabling the Cisco IOS DHCP Server Database
For procedures to enable and configure the Cisco IOS DHCP server database, see the “ DHCP Configuration
Task List
”
section in the
“
Configuring DHCP
”
chapter of the Cisco IOS IP Configuration Guide, Release 12.4
Monitoring DHCP Snooping Information
Table 119: Commands for Displaying DHCP Information
Displays the DHCP snooping configuration for a switch
show ip dhcp snooping
Displays only the dynamically configured bindings in the DHCP snooping
binding database, also referred to as a binding table. show ip dhcp snooping binding
Displays the DHCP snooping binding database status and statistics.
show ip dhcp snooping
database
Displays the DHCP snooping statistics in summary or detail form. show ip dhcp snooping
statistics
Display the dynamically and statically configured bindings. show ip source binding
If DHCP snooping is enabled and an interface changes to the down state, the switch does not delete the
statically configured bindings.
Note
Configuring DHCP Server Port-Based Address Allocation
Information About Configuring DHCP Server Port-Based Address Allocation
DHCP server port-based address allocation is a feature that enables DHCP to maintain the same IP address
on an Ethernet switch port regardless of the attached device client identifier or client hardware address.
When Ethernet switches are deployed in the network, they offer connectivity to the directly connected devices.
In some environments, such as on a factory floor, if a device fails, the replacement device must be working
immediately in the existing network. With the current DHCP implementation, there is no guarantee that DHCP
would offer the same IP address to the replacement device. Control, monitoring, and other software expect a
stable IP address associated with each device. If a device is replaced, the address assignment should remain
stable even though the DHCP client has changed.
When configured, the DHCP server port-based address allocation feature ensures that the same IP address is
always offered to the same connected port even as the client identifier or client hardware address changes in
the DHCP messages received on that port. The DHCP protocol recognizes DHCP clients by the client identifier
option in the DHCP packet. Clients that do not include the client identifier option are identified by the client
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
1282
Configuring DHCP Server Port-Based Address Allocation