Allied Telesis x510-28GPX, Command Reference Manual

Page: 2015 / 2822

C613-50170-01 Rev B Command Reference for x510 Series 2015
AlliedWare Plus™ Operating System - Version 5.4.7-1.x
DHCP S
NOOPING
C
OMMANDS
SERVICE DHCP
-
SNOOPING
service dhcp-snooping
Overview Use this command to enable the DHCP snooping service globally on the switch.
This must be enabled before other DHCP snooping configuration commands can
be entered.
Use the no variant of this command to disable the DHCP snooping service on the
switch. This removes all DHCP snooping configuration from the running
configuration, except for any DHCP snooping maximum bindings settings (
ip dhcp
snooping max-bindings command), and any DHCP snooping-based Access
Control Lists (ACLs), which are retained when the service is disabled.
Syntax
service dhcp-snooping
no service dhcp-snooping
Default DHCP snooping is disabled on the switch by default.
Mode Global Configuration
Usage For DHCP snooping to operate on a VLAN, it must be enabled on the switch by
using this command, and also enabled on the particular VLAN by using the
ip dhcp
snooping command.
For DHCP snooping to operate on a VLAN, it must:
• be enabled globally on the switch by using this command
• be enabled on the particular VLAN by using the ip dhcp snooping command
• have at least one port connected to a DHCP server configured as a trusted
port by using the
ip dhcp snooping trust command
If you disable the DHCP snooping service by using the no variant of this command,
all DHCP snooping configuration (including ARP security, but excluding maximum
bindings and ACLs) is removed from the running configuration, and the DHCP
snooping database is deleted from active memory. If you re-enable the service, the
switch repopulates the DHCP snooping database from the dynamic lease entries
in the database backup file (see the
ip dhcp snooping database command). The
lease expiry times are updated.
The DHCP snooping service cannot be enabled on a switch that is configured with
any of the following features, or vice versa:
• web authentication ( auth-web enable command)
• roaming authentication ( auth roaming enable command, auth roaming
disconnected command)
• guest VLAN authentication ( auth guest-vlan command).
• DHCP relay agent option ( ip dhcp-relay agent-option command)
Any ACLs on a port that permit traffic matching DHCP snooping entries and block
other traffic, will block all traffic if DHCP snooping is disabled on the port. If you
disable DHCP snooping on the switch using this command, you must also remove