H3C Technologies H3C S5560 Series Switches - Manual (Page 188)

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2. If the receiving interface has an address pool applied, the DHCP server selects an IPv6 address or
prefix and other configuration parameters from this address pool.
3. If no static address pool is configured and no address pool is applied to the receiving interface, the
DHCPv6 server selects an address pool depending on the client location.
{
Client on the same subnet as the server—The DHCPv6 server compares the IPv6 address of the
receiving interface with the subnets of all address pools. It selects the address pool with the
longest-matching subnet.
{
Client on a different subnet than the server—The DHCPv6 server compares the IPv6 address of
the DHCPv6 relay agent interface closest to the client with the subnets of all address pools. It
also selects the address pool with the longest-matching subnet.
To make sure address allocation functions correctly, keep the subnet used for dynamic assignment
consistent with the subnet where the interface of the DHCPv6 server or DHCPv6 relay agent
resides.
IPv6 address/prefix allocation sequence
The DHCPv6 server selects an IPv6 address/prefix for a client in the following sequence:
1. IPv6 address/prefix statically bound to the client's DUID and IAID and expected by the client.
2. IPv6 address/prefix statically bound to the client's DUID and IAID.
3. IPv6 address/prefix statically bound to the client's DUID and expected by the client.
4. IPv6 address/prefix statically bound to the client's DUID.
5. IPv6 address/prefix that was ever assigned to the client.
6. Assignable IPv6 address/prefix in the address pool/prefix pool expected by the client.
7. Assignable IPv6 address/prefix in the address pool/prefix pool.
8. IPv6 address/prefix that was a conflict or passed its lease duration. If no IPv6 address/prefix is
assignable, the server does not respond.
If a client moves to another subnet, the DHCPv6 server selects an IPv6 address/prefix from the address
pool that matches the new subnet.
Conflicting IPv6 addresses can be assigned to other DHCPv6 clients only after the addresses are in
conflict for one hour.
Configuration task list
Tasks at a glance
(Optional.) Perform the following tasks:
• Configuring IPv6 prefix assignment
• Configuring IPv6 address assignment
• Configuring network parameters assignment
(Required.) Configuring the DHCPv6 server on an interface
(Optional.) Setting the DSCP value for DHCPv6 packets sent by the DHCPv6 server