H3C Technologies H3C SecPath F1000-E - Manual (Page 737)

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Figure 367 Format of DUID-LL
A DUID based on link-layer address (DUID-LL) defined in RFC 3315 is used to identify a DHCPv6
device. Figure 367 shows the DUID-LL format, where:
• DUID type—The device supports DUID-LL as the DUID type with the value of 0x0003.
• Hardware type—The device supports Ethernet as the hardware type with the value of 0x0001.
• Link layer address—Its value is the bridge MAC address of the device.
IA
Identified by an IAID, an Identity Association (IA) provides a construct through which the obtained
addresses, prefixes, and other configuration parameters assigned from a server to a client are managed.
A client can maintain multiple IAs, each of which is configured on an interface to manage the addresses,
prefixes, and other configuration parameters obtained by that interface.
IAID
An IAID uniquely identifies an IA. It is chosen by the client and must be unique among the IAIDs on the
client.
PD
The Prefix Delegation (PD) is the lease record created by the DHCPv6 server for each assigned prefix. The
PD contains information such as the IPv6 prefix, client DUID, IAID, valid lifetime, preferred lifetime, lease
expiration time, and the IPv6 address of the requesting client.
Prefix selection process
Upon receiving a request, the DHCPv6 server selects the prefix and other configuration parameters from
the address pool that is applied to the interface receiving the request. An address pool may contain the
static prefixes configured for specific clients, or have a prefix pool referenced for dynamic assignment
from the specific prefix range.
A DHCPv6 server selects a prefix from the address pool according to the following sequence:
1. The desired static prefix with the DUID and IAID matching those of the client
2. The static prefix with the DUID and IAID matching those of the client
3. The desired static prefix with the DUID matching the client's DUID and with no client IAID specified
4. The static prefix with the DUID matching the client's DUID and with no client IAID specified
5. The desired idle prefix in the prefix pool
6. An idle prefix in the prefix pool