Stateless DHCPv6 + SLAAC [2/4]

This is a common LAN Deployment model in which DHCPv6 is used to advertise DNS and domain name and IPv6 prefixes are assigned using classic SLAAC (Stateless Address Auto-Configuration).

(Server configuration [> 12.4(24) T])

ipv6 dhcp pool SLAAC-POOL dns-server XXXX:YYYY:8B6B:90E0::57 dns-server 2001:DB8::57 domain-name nouri.com ! interface FastEthernet0/1 ipv6 address 2001:DB8:23::2/64 ipv6 nd other-config-flag ipv6 dhcp server SLAAC-POOL rapid-commit end

The Client gets the prefix from ND protocol (Network Discovery) through RS (Router Solicitation)/RA (Router Advertisement).

The Server sets a special flag in RA message to inform the client that it can get other stateful information like DNS and domain name through DHCP request.

Picture1: Stateless message exchange

Picture2: RA special flag

Client configuration [> 12.4(24) T]:

interface FastEthernet0/0 ipv6 address autoconfig ipv6 enable end

 

Verification:

R3(config-if)# *Oct 24 00:51:45.989: IPv6 DHCP: Sending INFORMATION-REQUEST to FF02::1:2 on FastEthernet0/0 *Oct 24 00:51:45.989: IPv6 DHCP: DHCPv6 changes state from IDLE to INFORMATION-REQUEST (STATELESS) on FastEthernet0/0 *Oct 24 00:51:46.001: IPv6 DHCP: Received REPLY from FE80::C803:37FF:FEAC:6 on FastEthernet0/0 *Oct 24 00:51:46.001: IPv6 DHCP: Adding server FE80::C803:37FF:FEAC:6 *Oct 24 00:51:46.005: IPv6 DHCP: Processing options *Oct 24 00:51:46.005: IPv6 DHCP: Configuring DNS server XXXX:YYYY:8B6B:90E0::57 *Oct 24 00:51:46.005: IPv6 DHCP: Configuring DNS server 2001:DB8::57 *Oct 24 00:51:46.005: IPv6 DHCP: Configuring domain name nouri.com *Oct 24 00:51:46.009: IPv6 DHCP: DHCPv6 changes state from INFORMATION-REQUEST to IDLE (REPLY_RECEIVED) on FastEthernet0/0 R3(config-if)#

 

R3#ii6 FastEthernet0/0 [up/up] FE80::C806:CFF:FE88:8 2001:DB8:23:0:C806:CFF:FE88:8 FastEthernet0/1 [up/up] FE80::C806:CFF:FE88:6 2001:DB8::203 R3#

R2 (Server) :

R2#sh ipv6 dhcp binding R2#sh ipv6 dhcp data R2#sh ipv6 dhcp interface FastEthernet0/1 is in server mode Using pool: SLAAC-POOL Preference value: 0 Hint from client: ignored Rapid-Commit: enabled R2# R2#sh ipv6 dhcp pool DHCPv6 pool: SLAAC-POOL DNS server: XXXX:YYYY:8B6B:90E0::57 DNS server: 2001:DB8::57 Domain name: nouri.com Active clients: 0 R2#

Note the DHCPv6 provides only DNS and domain name information, no IPv6 address assignment

Picture3: DHCP information request

Picture4: DHCP information reply

 

Picture5: ICMPv6 flow between DHCPv6 server and client interfaces: