H3C Technologies H3C S5560 Series Switches - Manual (Page 182)

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DHCPv6 overview
DHCPv6 provides a framework to assign IPv6 prefixes, IPv6 addresses, and other configuration
parameters to hosts.
DHCPv6 address/prefix assignment
An address/prefix assignment process involves two or four messages.
Rapid assignment involving two messages
As shown in Figure 62 , rapid assignment operates in the following steps:
1. The DHCPv6 client sends to the DHCPv6 server a Solicit message that contains a Rapid Commit
option to prefer rapid assignment.
2. If the DHCPv6 server supports rapid assignment, it responds with a Reply message containing the
assigned IPv6 address/prefix and other configuration parameters. If the DHCPv6 server does not
support rapid assignment, Assignment involving four messages is performed.
Figure 62 Rapid assignment involving two messages
Assignment involving four messages
As shown in Figure 63 , four-message assignment operates by using the following steps:
1. The DHCPv6 client sends a Solicit message to request an IPv6 address/prefix and other
configuration parameters.
2. The DHCPv6 server responds with an Advertise message that contains the assignable
address/prefix and other configuration parameters if either of the following conditions exists:
{
The Solicit message does not contain a Rapid Commit option.
{
The DHCPv6 server does not support rapid assignment even though the Solicit message
contains a Rapid Commit option.
3. The DHCPv6 client might receive multiple Advertise messages offered by different DHCPv6 servers.
It selects an offer according to the receiving sequence and server priority, and sends a Request
message to the selected server for confirmation.
4. The DHCPv6 server sends a Reply message to the client, confirming that the address/prefix and
other configuration parameters are assigned to the client.