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IPv6 WAN Link Addressing with DHCPv6 IA_NA

You can use DHCPv6 IA_NA to assign a global IPv6 address to the CPE WAN link. If the CPE sends a Solicit message that contains the IA_NA option to the BNG, the BNG acts as a DHCPv6 server and assigns a single IPv6/128 address to the WAN interface of the CPE.

Methods for Obtaining IPv6 Global Addresses for DHCPv6 IA_NA

You can set up the BNG to select global IPv6 addresses to be delegated to the requesting router in one the following ways:

  • An external source such as a AAA RADIUS server or a DHCP server using the DHCPv6 relay agent.

  • Dynamic assignment from a local pool of addresses that is configured on the BNG

Using a AAA RADIUS Server to Obtain IPv6 Addresses for DHCPv6 IA_NA

When the BNG needs to obtain a global IPv6 for the CPE WAN link and optionally a DHCPv6 prefix, it uses the values in one of the following RADIUS attributes:

  • Framed-IPv6-Prefix—The attribute contains a global IPv6 address with a prefix length of 128.

  • Framed-IPv6-Pool—The attribute contains the name of an address-assignment pool configured on the BNG from which the BNG can select a global IPv6 address to send to the CPE.

Both attributes are sent from the RADIUS server to the BNG in RADIUS Access-Accept messages.

Configuring an Address-Assignment Pool for Use by DHCPv6 IA_NA

This procedure shows how to configure IPv6 local address pools to allocate global IPv6 addresses to the CPE WAN link.

You must configure separate pools for DHCPv6 prefix delegation, DHCPv6 IA_NA, and NDRA.

To configure the pool to be used for DHCPv6 IA_NA:

  1. Create a pool and assign a name to it.
  2. Under family inet6, add IPv6 network prefixes to the pool.
  3. Configure the name of the IPv6 address range, and define the range by setting a low and high range of /128 addresses.