DHCP Snooping 3

If the DHCP snooping is globally disabled, all dynamic bindings are removed from the binding table.

Additional considerations when the switch itself is a DHCP client – The port(s) through which the switch submits a client request to the DHCP server must be configured as trusted. Note that the switch will not add a dynamic entry for itself to the binding table when it receives an ACK message from a DHCP server. Also, when the switch sends out DHCP client packets for itself, no filtering takes place. However, when the switch receives any messages from a DHCP server, any packets received from untrusted ports are dropped.

DHCP Snooping Configuration

Command Attributes

DHCP Snooping Status – Enables or disables DHCP snooping globally.

DHCP Snooping MAC-Address Verification – Enables or disables MAC address verification. DHCP packets will be dropped if the source MAC address in the Ethernet header of the packet is not same as the client’s hardware address in the DHCP packet.

Web – Click DHCP Snooping, Configuration.

Figure 3-144 DHCP Snooping Configuration

CLI – This example first enables DHCP Snooping, and then enables DHCP Snooping MAC-Address Verification.

Console(config)#ip dhcp snooping

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Console(config)#ip dhcp snooping verify mac-address

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Console(config)#

 

DHCP Snooping VLAN Configuration

Enables DHCP snooping on the specified VLAN.

Command Attributes

VLAN ID – ID of a configured VLAN. (Range: 1-4093)

DHCP Snooping Status – Enables or disables DHCP snooping for the selected VLAN. When DHCP snooping is enabled globally on the switch, and enabled on the specified VLAN, DHCP packet filtering will be performed on any untrusted ports within the VLAN.

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Accton Technology ES3528M-SFP manual Dhcp Snooping Configuration, Dhcp Snooping Vlan Configuration