ZyXEL Communications MES-2110 User Manual page 144

Chapter 19 IP Source Guard
The following table describes the labels in this screen.
Table 53 Configuration > IP Source Guard > DHCP > DHCP Snooping
Configuration
LABEL
DHCP Snooping Configuration
Action
DHCP snooping VLAN
Mode
DHCP Snooping
Option
Option82 Information
DHCP VLAN (Fixed)
Port
Trust
Untrust
All Port
Undo
144
DESCRIPTION
Select Enable to have the MES-2110 use DHCP snooping . You
still have to enable DHCP snooping on specific VLAN and specify
trusted ports.
Select Disable if you do not want to use this feature.
Note: If DHCP is enabled and there are no trusted ports,
DHCP requests will not succeed.
Select All-VLAN to have the Switch forward DHCP frames of any
VLANs to DHCP servers automatically.
Select Fixed to have the Switch forward DHCP frames of a
specific VLAN to DHCP servers.
Select Enable to have the MES-2110 add DHCP relay agent
option 82 information to DHCP requests that the MES-2110
relays to a DHCP server for each VLAN. Otherwise, select
Disable.
Enter a unique identifier (such as the MES-2110's MAC address)
for the DHCP relay agent. This must be globally unique. You can
enter up to 64 ASCII characters.
Enter the ID of a static VLAN; the valid range is between 1 and
4094.
This field displays the port number. If you configure the * port,
the settings are applied to all of the ports.
Use this to set trusted ports.
Trusted ports are connected to DHCP servers or other switches,
and the MES-2110 discards DHCP frames from trusted ports only
if the rate at which DHCP frames arrive is too high.
Use this to set un-trusted ports.
Untrusted ports are connected to subscribers, and the MES-2110
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.
Use this to configure all ports as trusted or un-trusted ports.
Click this to reset the values in this screen to their last-saved
values.
MES-2110 User's Guide