C613-50066-01 REV A
Command Reference for IE200 Series Industrial Managed PoE+ Switches
1077
AlliedWare Plus™ Operating System - Version 5.4.5I-0.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 (in NVS by default—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).
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
any DHCP snooping ACLs from the ports to maintain connectivity (no
access-group
command).