Configuring DHCP
DHCP Snooping Binding Database
Cisco 500 Series Stackable Managed Switch Administration Guide
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Disable DHCP Relay.
For regular DHCP Relay:
•
Enable DHCP Relay.
•
No need to enable Option 82 insertion.
DHCP Snooping Binding Database
DHCP Snooping builds a database (known as the DHCP Snooping Binding
database) derived from information taken from DHCP packets entering the switch
through trusted ports.
The DHCP Snooping Binding database contains the following data: input port,
input VLAN, MAC address of the client and IP address of the client if it exists.
The DHCP Snooping Binding database is also used by IP Source Guard and
Dynamic ARP Inspection features to determine legitimate packet sources.
DHCP Trusted Ports
Ports can be either DHCP trusted or untrusted. By default, all ports are untrusted.
To create a port as trusted, use the
DHCP Snooping Interface Settings
page.
Packets from these ports are automatically forwarded. Packets from trusted ports
are used to create the Binding database and are handled as described below.
If DHCP Snooping is not enabled, all ports are trusted by default.
How the DHCP Snooping Binding Database is Built
The following describes the switch handles DHCP packets when both the DHCP
client and DHCP server are trusted. The DHCP Snooping Binding database is built
in this process.
