H3C Technologies H3C S3600 Series Switches - Manual (Page 689)

4-6
To do… Use the command… Remarks
Enter system view system-view —
Enable DHCP snooping dhcp-snooping
Required
By default, the DHCP snooping
function is disabled.
Enter Ethernet port view
interface interface-type
interface-number
—
Specify the current port as a
trusted port
dhcp-snooping trust
Required
By default, after DHCP
snooping is enabled, all ports of
a switch are untrusted ports.
z If an S3600 Ethernet switch is enabled with DHCP snooping, the clients connected to it cannot
dynamically obtain IP addresses through BOOTP.
z You need to specify the ports connected to the valid DHCP servers as trusted to ensure that DHCP
clients can obtain valid IP addresses. The trusted port and the port connected to the DHCP client
must be in the same VLAN.
z To enable DHCP snooping on an S3600 switch that belongs to an IRF fabric, do not configure the
ports connecting to the DHCP clients and DHCP server to belong to different units of the fabric;
otherwise, the switch cannot record DHCP snooping entries although the clients can obtain IP
addresses.
z You are not recommended to configure both the DHCP snooping and selective Q-in-Q function on
the switch, which may result in the DHCP snooping to function abnormally.
Configuring DHCP Snooping to Support Option 82
Enable DHCP snooping and specify trusted ports on the switch before configuring DHCP snooping to
support Option 82.
Complete the following tasks to configure the DHCP snooping to support Option 82:
Task Remarks
Enabling DHCP-snooping Option 82 support Required
Configuring a handling policy for DHCP packets
with Option 82
Optional
Configuring the storage format of Option 82 Optional
Configuring the circuit ID sub-option Optional