Cisco Ios Dhcp Server Database; Dhcp Snooping Binding Database - Cisco Catalyst 2960-XR Security Configuration Manual

Ios release 15.0 2 ex1
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Cisco IOS DHCP Server Database

Figure 14: 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
agent stores the bindings in a file at a configured location. At the end of each entry is a checksum that accounts
for all the bytes from the start of the file through all the bytes associated with the entry. Each entry is 72 bytes,
followed by a space and then the checksum value.
To keep the bindings when the switch reloads, you must use the DHCP snooping database agent. If the agent
is disabled, dynamic ARP inspection or IP source guard is enabled, and the DHCP snooping binding database
Catalyst 2960-XR Switch Security Configuration Guide, Cisco IOS Release 15.0(2)EX1
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◦ The length values are variable, depending on the length of the string that you configure.
Configuring DHCP
OL-29434-01

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