Dhcp Relay - TRENDnet TI-PG1284i User Manual

TRENDnet User's Guide
Circuit-ID String The String of the circuit ID sub-option information.
Remote-ID String The String of the remote ID sub-option information.
Apply Click Apply to save your changes to the Switch.
Refresh Click Refresh to begin configuring this screen afresh.
DHCP Option 82 Port Settings
Port The port ID.
The String of the circuit ID sub-option information for the
Circuit-ID String
specific port.
The String of the remote ID sub-option information for the
Remote-ID String
specific port.
DHCP Option 82 Port Status
The field displays all of the ports' configurations.

DHCP Relay

Because the DHCPDISCOVER message is a broadcast message, and broadcasts only cross
other segments when they are explicitly routed, you might have to configure a DHCP
Relay Agent on the router interface so that all DHCPDISCOVER messages can be
forwarded to your DHCP server. Alternatively, you can configure the router to forward
DHCP messages and BOOTP message. In a routed network, you would need DHCP Relay
Agents if you plan to implement only one DHCP server.
The DHCP Relay that either a host or an IP router that listens for DHCP client messages
being broadcast on a subnet and then forwards those DHCP messages directly to a
configured DHCP server. The DHCP server sends DHCP response messages directly back
to the DHCP relay agent, which then forwards them to the DHCP client. The DHCP
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administrator uses DHCP relay agents to centralize DHCP servers, avoiding the need for a
DHCP server on each subnet.
Most of the time in small networks DHCP uses broadcasts however there are some
circumstances where unicast addresses will be used. A router for such a subnet receives
the DHCP broadcasts, converts them to unicast (with a destination MAC/IP address of the
configured DHCP server, source MAC/IP of the router itself). The field identified as the
GIADDR in the main DHCP page is populated with the IP address of the interface on the
router it received the DHCP request on. The DHCP server uses the GIADDR field to identify
the subnet the device and select an IP address from the correct pool. The DHCP server
then sends the DHCP OFFER back to the router via unicast which then converts it back to
a broadcast and out to the correct subnet containing the device requesting an address.
Configurations:
Users can enable/disable the DHCP Relay on the Switch. Users also can enable/disable the
DHCP Relay on a specific VLAN. If the DHCP Relay on the Switch is disabled, the DHCP
Relay is disabled on all VLANs even some of the VLAN DHCP Relay are enabled.
Applications

Application-1 (Over a Router)
The DHCP cleint-1 and DHCP client-2 are located in different IP segments. But they
allocate IP address from the same DHCP server.
DHCP Client-1 Switch Router
TI-PG1284i
Switch DHCP Client-2
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