Administrator Guide

To renew the lease time of the dynamically acquired IP, use the renew dhcp command on an interface already configured with a
dynamic IP address.
NOTE: To verify the currently configured dynamic IP address on an interface, use the show ip dhcp lease command.
The show running-configuration command output only displays ip address dhcp. The currently assigned dynamic
IP address does not display.
To configure and view an interface as a DHCP client to receive an IP address, use the following commands.
1. Enter INTERFACE Configuration mode on an Ethernet interface.
CONFIGURATION mode
interface type slot/port[/subport]
2. Acquire the IP address for an Ethernet interface from a DHCP network server.
INTERFACE mode
ip address dhcp
Dynamically assigned IP addresses can be released without removing the DHCP client operation on the interface on a switch
configured as a DHCP client.
3. Manually acquire a new IP address from the DHCP server by releasing a dynamically acquired IP address while retaining the DHCP
client configuration on the interface.
EXEC Privilege mode
release dhcp interface type slot/port[/subport]
4. Acquire a new IP address with renewed lease time from a DHCP server.
EXEC Privilege mode
renew dhcp interface type slot/port[/subport]
To display DHCP client information, use the following show commands in EXEC Privilege mode.
• To display statistics about DHCP client interfaces, use the show ip dhcp client statistics interface type slot/
port[subport] command.
• To clear DHCP client statistics on a specified or on all interfaces, use the clear ip dhcp client statistics {all |
interface type slot/port[/subport]} command.
• To display dynamic IP address lease information currently assigned to a DHCP client interface, use the show ip dhcp lease
[interface type slot/port[/subport]] command.
• To display log messages for all DHCP packets sent and received on DHCP client interfaces, use the debug ip dhcp client
packets [interface type slot/port[/subport] command.
• To display log message on DHCP client interfaces for IP address acquisition, IP address release, IP address and lease time renewal, and
release an IP address, use the [no] debug ip dhcp client events [interface type slot/port[/subport]]
command.
DHCP Client on a Management Interface
These conditions apply when you enable a management interface to operate as a DHCP client.
• The management default route is added with the gateway as the router IP address received in the DHCP ACK packet. It is required to
send and receive traffic to and from other subnets on the external network. The route is added irrespective when the DHCP client and
server are in the same or different subnets. The management default route is deleted if the management IP address is released like
other DHCP client management routes.
• ip route for 0.0.0.0 takes precedence if it is present or added later.
• Management routes added by a DHCP client display with Route Source as DHCP in the show ip management route and show
ip management-route dynamic command output.
• Management routes added by DHCP are automatically reinstalled if you configure a static IP route with the ip route command that
replaces a management route added by the DHCP client. If you remove the statically configured IP route using the
no ip route
command, the management route is reinstalled. Manually delete management routes added by the DHCP client.
• To reinstall management routes added by the DHCP client that is removed or replaced by the same statically configured management
routes, release the DHCP IP address and renew it on the management interface.
• Management routes added by the DHCP client have higher precedence over the same statically configured management route. Static
routes are not removed from the running configuration if a dynamically acquired management route added by the DHCP client
overwrites a static management route.
• Management routes added by the DHCP client are not added to the running configuration.
Dynamic Host Configuration Protocol (DHCP)
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