For [[en:dpi:bras_bng:bras_pppoe|PPPoE]]-PCRF subscribers form a DHCPv6 request, in which '' Client-Id '' (option 1, client DUID) is built as DUID-EN (vendorId=43823, 32 bits), then the client's VLANs (2 fields of 16 bits, if there is no VLAN, its value is 0), then 6 bytes of the client's MAC address. This Client-Id design ensures that the DUID remains unchanged, which is important for a DHCPv6 server.
For [[en:dpi:bras_bng:bras_pppoe|PPPoE]]-PCRF subscribers form a DHCPv6 request, in which '' Client-Id '' (option 1, client DUID) is built as DUID-EN (vendorId=43823, 32 bits), then the client's VLANs (2 fields of 16 bits, if there is no VLAN, its value is 0), then 6 bytes of the client's MAC address. This Client-Id design ensures that the DUID remains unchanged, which is important for a DHCPv6 server.
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The option format when using the configuration parameter ''dhcp_client_id=1'' is as follows:
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<code bash>[comtype][subs_id][tunnel_ip]</code>
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<note tip>For PPPoE subscribers, the tunnel IP (''tunnel_ip'') is always 0.</note>
=== Forming Access-Accept ===
=== Forming Access-Accept ===
After receiving a response from the DHCPv6 server, PCRF combines it with the one previously received from the "Access-Accept" Radius. Recall that in ''Access-Accept'' you can also specify DHCPv6 options in the form [[en:dpi:bras_bng:general_setup#ipv6_setup|special VSA]]. When aggregating responses, DHCPv6 options returned by the DHCPv6 server take precedence over these VSA attributes; for example, if a different list of DNS servers is specified in both the DHCPv6 response and the ''Access-Accept'', then the subscriber will be sent a list of DNS servers from the DHCPv6 server response.
After receiving a response from the DHCPv6 server, PCRF combines it with the one previously received from the "Access-Accept" Radius. Recall that in ''Access-Accept'' you can also specify DHCPv6 options in the form [[en:dpi:bras_bng:general_setup#ipv6_setup|special VSA]]. When aggregating responses, DHCPv6 options returned by the DHCPv6 server take precedence over these VSA attributes; for example, if a different list of DNS servers is specified in both the DHCPv6 response and the ''Access-Accept'', then the subscriber will be sent a list of DNS servers from the DHCPv6 server response.
