ZyXEL Communications MES-2110, User Manual

Page: 122 / 184

Chapter 17 IP Source Guard
MES-2110 User’s Guide
122
DHCP Snooping
Option Select Enable to have the Switch add DHCP relay agent option
82 information to DHCP requests that the Switch relays to a
DHCP server for each VLAN. Otherwise, select
Disable .
DHCP VLAN (Fixed) Enter the ID of a static VLAN; the valid range is between 1 and
4094.
Port This field displays the port number. If you configure the * port,
the settings are applied to all of the ports.
Trust Use this to set trusted ports.
Trusted ports are connected to DHCP servers or other switches,
and the Switch discards DHCP frames from trusted ports only if
the rate at which DHCP frames arrive is too high.
Untrust Use this to set un-trusted ports.
Untrusted ports are connected to subscribers, and the Switch
discards DHCP frames from untrusted ports in the following
situations:
• The frame is a DHCP server frame (for example, OFFER, ACK,
or NACK).
• The source MAC address and source IP address in the frame
do not match any of the current bindings.
• The frame is a RELEASE or DECLINE frame, and the source
MAC address and source port do not match any of the current
bindings.
• The rate at which DHCP frames arrive is too high.
All Port Use this to configure all ports as trusted or un-trusted ports.
Undo Click this to reset the values in this screen to their last-saved
values.
Apply Click Apply to save your changes to the Switch’s run-time
memory. The Switch loses these changes if it is turned off or
loses power, so use the
Save link on the top navigation panel to
save your changes to the non-volatile memory when you are
done configuring.
DHCP Snooping Status
Action
This shows whether DHCP snooping is enabled or disabled.
DHCP snooping VLAN
Mode This shows whether the Switch forwards DHCP frames of any
VLANs or specific VLANs to DHCP servers.
DHCP Snooping
Option This specifies whether or not the Switch enabled or disabled
adding DHCP relay agent option 82 information to DHCP requests
that the Switch relays to a DHCP server for each VLAN.
DHCP VLAN (Fixed) This shows the specific VLAN ID.
Trust/Untrust This shows whether the port is trusted or un-trusted.
Table 49 Configuration > DHCP Snooping > DHCP Snooping Configuration
LABEL DESCRIPTION