[Edgecore SONiC] DHCP Relay Follow

When the DHCP Relay service is enabled, and the switch sees a DHCP client request from an attached host, it inserts its own IP address into the request so that the DHCP server will know the subnet where the client is located. Then, the switch forwards the packet to a DHCP server (destination IP) on another network. When the server receives the DHCP request, it allocates a free IP address for the DHCP client from its defined scope for the DHCP client’s subnet, and sends a DHCP response back to the DHCP Relay agent (the switch). The switch then passes the DHCP response received from the server to the client.

• Switch model name:

  AS7726-32X, AS7326-56X, AS7816-64X, AS5835-54X(T), AS4630-54PE, AS9716-32D, AS8000(Minipack), Wedge100BF-32X

• Edgecore SONiC version:

  • Edgecore-SONiC_20201123_130028_ec202006_74

  • Edgecore-SONiC_20201229_070315_ec202006_101

  • Edgecore-SONiC_20201229_070315_ec202006_bfn_65(Wedge100BF-32X)

• DHCP relay support VLAN interface only.
• DHCP relay won’t work well when the VLAN is belong to Non-default VRF.

Step 1. Configure VLAN and IP address properly (Refer to VLAN and inter-VLAN Routing)

Step 2. Add DHCP relay server IP address to VLAN 20

admin@sonic:~$ sudo config vlan dhcp_relay add 20 192.168.10.2

• Check the setting information by SONiC command.

admin@sonic:~$ show vlan brief         
+-----------+------------------+-----------+----------------+-----------------------+
|   VLAN ID | IP Address       | Ports     | Port Tagging   | DHCP Helper Address   |
+===========+==================+===========+================+=======================+
|        10 | 192.168.10.10/24 | Ethernet4 | untagged       |                       |
+-----------+------------------+-----------+----------------+-----------------------+
|        20 | 192.168.20.10/24 | Ethernet2 | untagged       | 192.168.10.2          |
+-----------+------------------+-----------+----------------+-----------------------+