Role and configuration of DHCP option43

Role and configuration of DHCP option43.

The DHCP Server can specify the address of the AC when it issues an IP address to the AP through the Option43 attribute. Enable DHCP Server on the L3 Switch and configure Option43 correctly. For example, the AP belongs to VLAN 100, which is the 192.168.100.0/24 segment, and the IP address of the AC is 192.168.10.100/24, and the DHCP Server is configured as follows:

[AC] dhcp server ip-pool vlan100

[AC-dhcp-pool-vlan100] network 192.168.100.0 mask 255.255.255.0

[AC-dhcp-pool-vlan100] gateway-list 192.168.100.254

[AC-dhcp-pool-vlan100] option 43 hex 80070000 01 C0A80A64

Explanation of the above option43 field:

#80: Option type, fixed to 80, 1 byte. 

#07: Option length, indicates the length of the content after it (number of hexadecimal numbers, here it means 7 hexadecimal numbers after it, 0B means 11 hexadecimal numbers after it), one byte. If carrying two AC IP addresses, the field is 0B; if carrying three AC IP addresses, the field is 0F (15 bytes).

#0000: Server type, fixed allocation is 0000, 2 bytes. 

#01: Indicates the number of AC IP addresses carried, one byte. If carrying two AC IP addresses, the field is 02, if carrying three AC IP addresses, the field is 03. 

#C0A80A64: Hexadecimal representation of AC IP address 192.168.10.100.