More Information About HW-DHCPv6-Option (189)

Format of HW-DHCPv6-Option (189)

The values delivered through the RADIUS attribute must be in the following format:

    0                   1                    2                3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2
   +---------------+---------------+---------------------------------+
   |     Type      |    Length     |        Option Type              |
   +---------------+---------------+---------------------------------+
   |     value
   +-----------------

The description of each field is as follows:

• Option Type: 2 bytes

• Value: option value

HW-DHCPv6-Option (189) Attribute Rules

• Rule 1: A maximum of eight options can be delivered. If eight valid options have been parsed, the subsequent options are ignored.

• Rule 2: If a duplicate option is delivered, it replaces the one previously delivered.

  

  Example for rules 1 and 2: If eight options are delivered and the first and eighth options have the same number, the eighth option replaces the first option. That is to say, only seven options are available. The ninth option can also be parsed successfully in this case.

  If the eight delivered options are different from each other, the ninth delivered option will be ignored.

• Rule 3: The attribute can be delivered only in Access-Response packets, not in CoA messages.

• Rule 4: The following options cannot be delivered currently.

  Option Number	Description
  1	Client-identifier option
  2	Server-identifier option
  3	Identity Association for the Non-temporary Address (IA_NA) option
  4	Identity association for temporary addresses (IA_TA)
  5	IPv6 address option
  6	Option request option
  7	Priority option
  8	Time option
  9	Relay information option
  10	Unassigned.
  11	Authentication option
  12	Option that allows a client to unicast messages to a server
  13	Status code option
  14	Two-step message exchange option
  15	User level option
  18	Relay agent interface ID option
  19	Reconfigure Message option
  20	Reconfigure Accept option
  25	Identity Association for Prefix Delegation (IA_PD) option
  26	Prefix option
  37	Relay agent remote ID option
  38	Relay agent subscriber ID option

• Rule 5: If the supported RADIUS attributes need to be delivered through the HW-DHCPv6-Option, they must be translated, and corresponding check rules are used during the delivery. For example, a packet can carry two DNSs at most, and the two DNSs have the same priority, but the DNS that is parsed the latest overrides the other one, which is different from the processing in the case of HW-DNS-Server-IPv6-Address.

  Option Number	Description	RADIUS Attribute Number	Attribute Name
  64	IPv6 tunnel name in a CGN scenario	26-166	HW-DS-Lite-Tunnel-Name
  		144	DS-Lite-Tunnel-Name
  86	PCP server name	26-167	HW-PCP-Server-Name
  23	IPv6 address of the DNS server	26-154	HW-DNS-Server-IPv6-Address

  

  The RADIUS attributes about DHCPv4 lease (HW-Lease-Time, HW-Renewal-Time, and HW-Rebinding-Time) can be translated and belong to independent options (51, 58, and 59, respectively).

  DHCPv6 lease-related fields belong to Option 5 and Option 26. To avoid the conflict with the options listed in Rule 4, the RADIUS attributes about DHCPv6 lease (HW-IPv6-Prefix-Lease and HW-IPv6-Address-Lease) cannot be translated through HW-DHCPv6-Option.

• Rule 6: The RADIUS server ensures the validity of options. The BNG does not check the validity of options. If a RADIUS attribute in Rule 5 is translated to a supported RADIUS attribute and delivered, the system checks the validity of the RADIUS attribute. If the attribute fails to pass the check, it is not parsed.
• Rule 7: The option attributes delivered by the RADIUS server take precedence over locally configured option attributes.
• Rule 8: Before parsing an option in the HW-DHCPv6-Option attribute, the BRAS determines whether this option can be delivered and checks the basic length of the attribute. If this option cannot be delivered or its length does not meet the requirement, the BRAS ignores this option and continues its traversing. After a round of comprehensive traversing, the BRAS examines ineligible options to see whether these options need to be translated to RADIUS attributes for delivery. If some options cannot be delivered, the corresponding users will fail to go online.
• Rule 9: To trigger a user that goes offline unexpectedly to go online again, the options sent to the RADIUS server can only be the Option 15,16,17,18,37,38,79 stored in the backup table of the unexpected logout.