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• If the DHCPv6 client does not receive a response from the DHCPv6 server after sending a
Renew message at T1, it multicasts a Rebind message to all DHCPv6 servers at T2. Typically,
the value of T2 is 0.8 times the preferred lifetime.
• The DHCPv6 server responds with a Reply message, informing the client whether the lease is
renewed.
• If the DHCPv6 client does not receive a response from any DHCPv6 server before the valid
lifetime expires, the client stops using the address/prefix.
For more information about the valid lifetime and the preferred lifetime, see "Configuring basic IPv6
s
ettings."
Stateless DHCPv6
Stateless DHCPv6 enables a device that has obtained an IPv6 address/prefix to get other
configuration parameters from a DHCPv6 server.
The device performs stateless DHCPv6 if an RA message with the following flags is received from
the router during stateless address autoconfiguration:
• The managed address configuration flag (M flag) is set to 0.
• The other stateful configuration flag (O flag) is set to 1.
For more information about stateless address autoconfiguration, see "Configuring basic IPv6
s
ettings."
Figure 96 Stateless DHCPv6 operation
As shown in Figure 96, stateless DHCPv6 operates in the following steps:
1. The DHCPv6 client sends an Information-request message to the multicast address of all
DHCPv6 servers and DHCPv6 relay agents. The Information-request message contains an
Option Request option that specifies the requested configuration parameters.
2. The DHCPv6 server returns to the client a Reply message containing the requested
configuration parameters.
3. The client checks the Reply message. If the obtained configuration parameters match those
requested in the Information-request message, the client uses these parameters to complete
configuration. If not, the client ignores the configuration parameters. If the client receives
multiple replies with configuration parameters matching those requested in the
Information-request message, it uses the first received reply.
Protocols and standards
• RFC 3736, Stateless Dynamic Host Configuration Protocol (DHCP) Service for IPv6
• RFC 3315, Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
• RFC 2462, IPv6 Stateless Address Autoconfiguration
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