Dhcp Relay Configuration Task Sequence - Accton Technology ES4710BD User Manual

As shown in the above figure, the DHCP client and the DHCP server are in different networks, the
DHCP client performs the four DHCP steps as usual yet DHCP relay is added to the process.
1. The client broadcasts a DHCPDISCOVER packet, and DHCP relay inserts its own IP
address to the relay agent field in the DHCPDISCOVER packet on receiving the packet,
and forwards the packet to the specified DHCP server (for DHCP frame format, please refer
to RFC2131).
2. On the receiving the DHCPDISCOVER packet forwarded by DHCP relay, the DHCP server
sends the DHCPOFFER packet via DHCP relay to the DHCP client.
3. DHCP client chooses a DHCP server and broadcasts a DHCPREPLY packet, DHCP relay
forwards the packet to the DHCP server after processing.
4. On receiving DHCPREPLY, the DHCP server responds with a DHCPACK packet via
DHCP relay to the DHCP client.
DHCP relay can not only send DHCP broadcasting packets to the specified DHCP servers, but can
also send other specified UDP broadcast packet to specified servers.

14.3.1 DHCP Relay Configuration Task Sequence

1. Enable DHCP relay.
2. Configure DHCP relay to forward DHCP broadcast packet.
3. Configure DHCP relay to forward other UDP broadcast packet.
4. Disable DHCP relay from forwarding DHCP broadcast packet.
1. Enable DHCP relay.
DHCP server and DHCP relay is enabled as the DHCP service is enabled..
2. Configure DHCP relay to forward DHCP broadcast packet.
Command
Global Mode
ip forward-protocol udp <port>
no ip forward-protocol udp <port>
Interface Mode
ip helper-address <ipaddress>
no ip helper-address <ipaddress>
3. Configure DHCP relay to forward other UDP broadcast packet.
Command
Global Mode
ip forward-protocol udp <port>
no ip forward-protocol udp <port>
ip helper-address <ipaddress>
no ip helper-address <ipaddress>
EES4710BD 10 Slots L2/L3/L4 Chassis Switch
Fig 14-2 DHCP relay
Explanation
The UDP port used for DHCP broadcast packet
forwarding.
Sets the destination IP address for DHCP relay
forwarding;
<ipaddress>" command cancels the setting.
Explanation
Specifies the DHCP relay forwarding protocol by
setting UDP port; the "no ip forward-protocol
udp <port>" command cancels the setting.
Sets the destination IP address for DHCP relay
forwarding;
<ipaddress>" command cancels the setting.
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the "no ip helper-address
the "no ip helper-address