Information About DHCP
• Remote-ID suboption fields
Figure 88: User-Configured Suboption Packet Formats
Cisco IOS DHCP Server Database
During the DHCP-based autoconfiguration process, the designated DHCP server uses the Cisco IOS DHCP
server database. It has IP addresses, address bindings, and configuration parameters, such as the boot file.
An address binding is a mapping between an IP address and a MAC address of a host in the Cisco IOS DHCP
server database. You can manually assign the client IP address, or the DHCP server can allocate an IP address
from a DHCP address pool. For more information about manual and automatic address bindings, see the
"Configuring DHCP" chapter of the Cisco IOS IP Configuration Guide, Release 12.4.
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.
DHCP Snooping Binding Database
When DHCP snooping is enabled, the switch uses the DHCP snooping binding database to store information
about untrusted interfaces. The database can have up to 64,000 bindings.
Each database entry (binding) has an IP address, an associated MAC address, the lease time (in hexadecimal
format), the interface to which the binding applies, and the VLAN to which the interface belongs. The database
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
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◦ The length values are variable, depending on the length of the string that you configure.
◦ The remote-ID type is 1.
◦ The length values are variable, depending on the length of the string that you configure.