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Industrial Managed
Ethernet Switch – EH9711
User Manual
Page
35
of
223
To enable the DHCP Snooping feature, select the
Enabled
option from the dropdown menu behind the
Snooping Mode
option under the
DHCP Snooping Configuration
webpage as shown in Figure 2.22. By default, all interfaces of EH9711 are
untrusted for DHCP Snooping. To configure specific port(s) as trusted port(s), simply select the
Trusted
option under the
Mode
column for that particular Port(s). Finally, click the
Save
button at the bottom of the webpage to activate the DHCP
Snooping on the selected port(s). Click Reset button to undo any change made locally and revert to previously saved values.
Table 2.15 describes the options of DHCP Snooping Configuration.
Figure 2.22 Webpage to Configure DHCPv4 Snooping
Table 2.15 Description of DHCP Snooping Configuration
Field Label
Description
Factory
Default
Snooping Mode
Indicates the DHCP snooping mode operation. Possible modes are:
Enabled
: Enable DHCP snooping mode operation. When DHCP snooping
mode operation is enabled, the DHCP request messages will be forwarded to
trusted ports and only allow reply packets from trusted ports.
Disabled
: Disable DHCP snooping mode operation.
Disabled
Port Mode Configuration
Indicates the DHCP snooping port mode. Possible port modes are:
Trusted
: Configures the port as trusted source of the DHCP messages.
Untrusted
: Configures the port as untrusted source of the DHCP messages.
Trusted
2.4.2
Relay
A DHCP relay agent is a small program that relays DHCP/BOOTP messages between clients and servers on different subnets.
DHCP/BOOTP relay agents are parts of the DHCP and BOOTP standards and function according to the Request for Comments
(RFCs). It stores the incoming interface IP address in the GIADDR field of the DHCP packet. The DHCP server can use the
value of GIADDR field to determine the assigned subnet. For such condition, please make sure the switch configuration of
VLAN interface IP address and PVID (Port VLAN ID) correctly.
A relay agent relays DHCP/BOOTP messages that are broadcast on one of its connected physical interfaces, such as a network
adapter, to other remote subnets to which it is connected by other physical interfaces. Figure 2.23 shows the
DHCP Relay
configuration webpage. Users can enable the DHCP Relay by selecting the
Enabled
box behind the
Relay Mode
option. Then,
users can enter a Relay server’s IP address in the
Relay
Server
field.