Reference Guide

Dynamic Host Configuration Protocol (DHCP) | 167
Debug DHCP Server
To display debug information, follow this step:
DHCP Clear Commands
To clear DHCP binding entries, follow these steps:
Configure the System to be a Relay Agent
DHCP clients and servers request and offer configuration information using broadcast DHCP messages.
Routers do not forward broadcasts, so if there are no DHCP servers on the subnet, the client does not
receive a response to its request and therefore cannot access the network.
You can configure an interface on the Dell Force10 system to relay the DHCP messages to a specific
DHCP server using the
ip helper-address dhcp-address command from INTERFACE mode (Figure 9-4).
Specify multiple DHCP servers by entering the
ip helper-address dhcp-address command multiple times.
When you configure the
ip helper-address command, the system listens for DHCP broadcast messages on
port 67. The system rewrites packets received from the client and forwards it using unicast; the system
rewrites the destination IP address and writes its own address as the relay device. Responses from the
server are unicast back to the relay agent on port 68, and the relay agent rewrites the destination address
and forwards the packet to the client subnet using broadcast.
Task Command Syntax Command Mode
Display debug information for DHCP
server.
debug ip dhcp server [events | packets]
EXEC Privilege
Task Command Syntax Command Mode
Clear DHCP binding entries for the entire binding
table.
clear ip dhcp binding
EXEC Privilege
Clear a DHCP binding entry for an individual IP
address.
clear ip dhcp binding ip address
EXEC Privilege
Clear a DHCP address conflict.
clear ip dhcp conflict
EXEC Privilege
Clear DHCP server counters.
clear ip dhcp server statistics
EXEC Privilege
Note: DHCP relay is not available on Layer 2 interfaces and VLANs.