How do you configure a Cisco router as a stateless DHCPv6 (Dynamic Host Configuration Protocol version 6) client?
Enable IPv6 routing, create a link-local address with ipv6 enable, then use ipv6 address autoconfig to use SLAAC (Stateless Address Autoconfiguration) and receive DHCPv6 options.
Step-by-step:
- Enable IPv6 routing:
R2(config)# ipv6 unicast-routing
- Create a link-local address:
R2(config)# interface g0/0/1
R2(config-if)# ipv6 enable
This creates an LLA (Link-Local Address) using EUI-64 (Extended Unique Identifier (64-bit)) (Cisco IOS (Internetwork Operating System) default for routers).
- Enable SLAAC for addressing:
R2(config-if)# ipv6 address autoconfig
- Verify the GUA (Global Unicast Address):
R2# show ipv6 interface brief
- Verify DHCPv6 options received:
R2# show ipv6 dhcp interface g0/0/1
Confirms DNS (Domain Name System) server and domain name were received from the stateless DHCPv6 server.
Tip: ipv6 address autoconfig tells the router interface to behave like a SLAAC client — it listens for RA (Router Advertisement) messages and creates its own GUA, plus contacts a DHCPv6 server if the O flag is set.
Go deeper:
RFC 4862 — IPv6 SLAAC — the SLAAC behaviour ipv6 address autoconfigmakes the interface perform.