IPV6 DHCP option 52 for Master Discovery.
In an IPv4 deployment, AP is capable of discovering Master Controller address using DHCPv4 option 43. Hence IPv4 deployment was more convenient when compared to IPV6, as IPv6 deployment had no such supporting feature. Starting AOS Version 8.1, for an IPv6 deployment, AP will now request option 52 in the parameter request list of Solicit. If the DHCPv6 server is configured for option 52, it will return Controller v6 address in the reply packet. AP will then parse and record the Master IPv6 address in it's flash and contact the Controller.
- There are no configurations necessary on the AP or on the controller for this feature.
- Configuration needs to be done on DHCPv6 server to send Controller address in option 52.
- If controller is used as DHCPv6 server for the APs, then below configuration is necessary.
ipv6 dhcp pool vlan127
option 52 ip 2017:2018:2019:2020::1 --> Master Controller Address
AP requesting option 52 can be seen from the below wireshark captures.
Below IPV6 show command displays how an AP discovered it's Master ip address.
(7010) #show ap consolidated-provision info ap-name ac:a3:1e:c4:fb:98
ap name: ac:a3:1e:c4:fb:98
ipv4 address: none
ipv6 address type: dynamic(DHCPv6)
ipv6 address: 2000:2001:2002:2003::9e
ipv6 lease: 7500
ipv6 gateway: fe80::b:8600:7f9a:4a37
master discover type: DHCPv6 --> Master Discovery
previous lms: none
lms addrs : 2017:2018:2019:2020::1