H3C Technologies H3C S12500 Series Switches - Manual (Page 148)

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client against the subnets of all address pools, and selects the address pool with the
longest-matching subnet.
To avoid wrong address allocation, keep the subnet used for dynamic assignment consistent with
the subnet where the interface of the DHCPv6 server or DHCPv6 relay agent resides.
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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.
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Configuration task list
Tasks at a glance
(Optional.) Perform the following tasks:
•
788H
Configuring IPv6 prefix assignment
•
789H
Configuring IPv6 address assignment
•
790H
Configuring network parameters assignment
(Required.)
791H
Configuring the DHCPv6 server on an interface
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Configuring IPv6 prefix assignment
Use the following methods to configure IPv6 prefix assignment:
• Configure a static IPv6 prefix binding in an address pool—If you bind a DUID and an IAID to an
IPv6 prefix, the DUID and IAID in a request must match those in the binding before the DHCPv6
server can assign the IPv6 prefix to the DHCPv6 client. If you only bind a DUID to an IPv6 prefix, the
DUID in the request must match the DUID in the binding before the DHCPv6 server can assign the
IPv6 prefix to the DHCPv6 client.
• Apply a prefix pool to an address pool—The DHCPv6 server dynamically assigns an IPv6 prefix
from the prefix pool in the address pool to a DHCPv6 client.
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Configuration guidelines
• An IPv6 prefix can be bound to only one DHCPv6 client. You cannot modify bindings that have
been created. To change the binding for a DHCPv6 client, you must delete the existing binding first.