Specifications

90 Chapter 4. Configuring Special Features
Example:
To define a new option with a code of 128, a minimum number of IP addresses of 1, a maximum number of
IP addresses of 4, of type ÒIP addressÓ, type:
dhcp add 128 1 4 ipAddress
This information implies that:
¥ Some DHCP client will know about the option with code 128.
¥ Option 128 allows IP addresses.
¥ The server can have a minimum of 1 IP address.
¥ The server can have up to 4 IP addresses.
¥ The administrator will still need to set the option value either globally, specific to a subnetwork, or
specific to a client for the option to have any meaning.
To delete the definition of the option with code 128, type:
dhcp del 128
The values for this option that have been set globally, specific to a subnetwork, or specific to a client will not
be removed. The administrator must remove those values explicitly. Well-known type option codes cannot be
changed or deleted.
DHCP Information File
DHCP information is kept in the file DHCP.DAT, a self-contained file.
This file contains all DHCP information including:
¥ the option definitions
¥ the subnetworks that have been added
¥ the client lease information
¥ the option values that have been set
This file can be uploaded/downloaded from one router to another.
Clearing All DHCP Information
If necessary, you can clear all DHCP information from memory, including all leases and all global DHCP
information. To do so, enter this command:
dhcp clear all records
At this point, the DHCP information is cleared from memory, but the DHCP.DAT file remains unchanged. To
clear the information from the DHCP.DAT file as well, enter:
save
Note: You cannot abbreviate the word records in the dhcp clear all records command.