ZyXEL Communications ES-100, Руководство пользователя

Страница: 144 / 232

Chapter 19 IP Source Guard
MES-2110 User’s Guide
144
The following table describes the labels in this screen.
Table 53 Configuration > IP Source Guard > DHCP > DHCP Snooping
Configuration
LABEL DESCRIPTION
DHCP Snooping Configuration
Action
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.
DHCP snooping VLAN
Mode 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.
DHCP Snooping
Option 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.
Option82 Information 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.
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 MES-2110 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 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.
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.