Stateless DHCPv6 Server and Client Auto-configuration.
DHCPv6 Stateless Configuration is a method used in IPv6 networks to provide additional network configuration information to devices, while the devices generate their own IPv6 addresses independently.
Key aspects include:
Address Autoconfiguration: Devices configure their own IPv6 addresses using Router Advertisements, a process known as SLAAC (Stateless Address Autoconfiguration).
DHCPv6 Server Role: The DHCPv6 server provides supplementary network configuration details such as DNS server addresses, but not the IP addresses themselves.
Efficiency and Simplicity: This approach simplifies network configuration and reduces the administrative overhead of managing IP address allocations.
During the SLAAC process, the client receives information to create an IPv6 global unicast address.
This includes the default gateway information from the source IPv6 address in the RA message, which is the link-local address of the router.
A stateless DHCPv6 server can be used to provide information that might not be included in the RA message (DNS server address and the domain name).
Stateless DHCPv6 Server Configuration command terms:
The ipv6 dhcp server interface command binds the DHCPv6 pool to the interface.
The O flag needs to be changed from 0 to 1 using the interface command ipv6 nd other-config-flag.
Stateless DHCPv6 Server Configuration
we use the topology below to configure stateless DHCP servers and clients.
R1(config)#ipv6 unicast-routing
R1(config)#ipv6 dhcp pool Stateless_DHCP
R1(config-dhcpv6)#dns-server AAAA:BBBB:CCCC:DDDD::FFFF
R1(config-dhcpv6)#domain-name orbitCO.com
R1(config-dhcpv6)#exit
R1(config)#interface s0/0/0
R1(config-if)#ipv6 address 2001:df6:adac:1::1/64
R1(config-if)#ipv6 dhcp server Stateless_DHCP
R1(config-if)#ipv6 nd other-config-flag
Stateless DHCPv6 Client Configuration
we use the same topology below to configure a stateless DHCP client.
Stateless DHCPv6 Client Configuration command terms.
The ipv6 enable command is used to enable a global unicast addressing.
The ipv6 address autoconfig command enables automatic configuration of IPv6 addressing using SLAAC
R2(config)#interface s0/0/0
R2(config-if)#ipv6 enable
R2(config-if)#ipv6 address autoconfig
R2(config-if)#exit
Stateless DHCPv6 Verification.
R2#show ipv6 interface s0/0/0
Serial0/0/0 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::2
No Virtual link-local address(es):
Stateless address autoconfig enabled
Global unicast address(es):
2001:DF6:ADAC:1::2, subnet is 2001:DF6:ADAC:1::/64 [EUI/CAL/PRE]
valid lifetime 2591259 preferred lifetime 604059
Joined group address(es):
FF02::1
FF02::1:FF00:2
MTU is 1500 bytes
ICMP error messages limited to one every 100 milliseconds
ICMP redirects are enabled
ICMP unreachables are sent
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is 30000 milliseconds (using 30000)
ND RAs are suppressed (periodic)
Hosts use stateless autoconfig for addresses.
From the display above, the show ipv6 interface command shows that the router has “Stateless address autoconfig enabled” and has an IPv6 global unicast address (2001:DF6:ADAC:1::2) and displays the subnet address (2001:DF6:ADAC:1::/64) as well.
The IPv6 global unicast address was created using SLAAC which includes the prefix which can be found in the RA message.
The Interface ID was generated using EUI-64 which is displayed to the right of the subnet address.
Duplicate Address Detection (DAD) is used to verify that no one else on your network is using the same address you created.
In conclusion, Stateless DHCPv6 is useful in networks where devices can self-assign IP addresses but still require additional network configuration from a central server.
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