Maipu Administration Guide

Configure the DHCP Relay to Support Option82

Network Requirements

On the DHCP relay device, Option82 is enabled.
For Option82 sub-option Remote ID, specify the content as 0102030405.
The DHCP relay Device2 adds Option82 in a request packet and forwards the request to DHCP server. The DHCP server then allocates IP addresses in the 1.0.0.0/24 network segment to the client.

Network Topology

Networking for Configuring the DHCP Relay to Support Option82

Figure 3-4 Networking for Configuring the DHCP Relay to Support Option82

Configuration Steps

Step 1: Configure VLAN, and add the port to the corresponding VLAN. Configure the IP address of the interface (omitted).

Step 2: Configure the DHCP server.

Device1# configure terminal
Device1(config)#interface vlan2
Device1(config-if-vlan2)#ip dhcp server
Device1(config-if-vlan2)#exit
Device1(config)#ip dhcp pool dynamic-pool
Device1(dhcp-config)#network 1.0.0.0 255.255.255.0
Device1(dhcp-config)#default-router 1.0.0.1
Device1(dhcp-config)#exit

#Configure the static route to the segment 1.0.0.0/24.

Device1(config)#ip route 1.0.0.0 255.255.255.0 2.0.0.2

Step 3: Configure the DHCP relay device Device2 and Option82 parameters.

#Configure the IP address of the DHCP relay server as 2.0.0.1.

Device2(config)#interface vlan3
Device2(config-if-vlan3)#ip dhcp relay
Device2(config-if-vlan3)#ip dhcp relay server-address 2.0.0.1

#Enable Option82, and configure the sub option remote-ID as 0102030405.

Device2(config)#ip dhcp relay information option
Device2(config)#ip dhcp relay information remote-id hex 0102030405

Step 4: Check the result.

Query the information of the IP address distributed for the client on Device1.

Device1#show ip dhcp pool danymic-pool1 lease 
IP Address        MAC Address        Vendor Id       Type     Time Left(s)
-------------     ----------------   -------------   -------  ---------- 
1.0.0.2           0001.7a6a.0268     Global          Lease    107992

On the DHCP client, query one IP address of the segment 1.0.0.0/24 got by the network card.

On the DHCP server, capture the packet, and you can verify that the remote-id of option82 in the discover packet received by the server is 0102030405.

After Option82 is enabled, its sub-option Circuit ID is filled with the receiving interface index and the system ID of the relay device.