4. SLAAC
4.1. In This Chapter
This chapter provides information about using SLAAC, including theory, supported features and configuration process overview.
 | Note: The information in this section applies only to the 7750 SR. |
Topics in this chapter include:
4.2. Stateless Address Auto-configuration (SLAAC) Management
4.3. SLAAC Principles
In a Triple Play network, client devices can use SLAAC to dynamically obtain their IP address and other network configuration information.
- During boot-up, the client sends a Router Solicit (RS) message to get an IP prefix.
- The BNG address server can assign a prefix statically to the subscriber through Radius or LUDB. Or, dynamically through the use of the local-address-server.
- The BNG address server will reply to the client with a Router Advertisement which contains a /64 prefix.
4.4. Configuration Overview
The ICMP6 Router Solicit is the primary trigger for SLAAC host creation. It is also possible to use the DHCPv4 message to trigger a SLAAC host creation using the “IPoE-linking” feature. The SLAAC host can use RADIUS or LUDB authentication, as well as bypass authentication. Address assignment can be assigned statically or dynamically. Static prefix assignment is accomplished through RADIUS or LUDB. Dynamic prefix assignment requires the use of the local-address-server (reusing the local DHCPv6 server), and a pool name returned from RADIUS or LUDB. The DHCPv6 server for SLAAC is used for address management only, there are no lease state associated with SLAAC users. The DHCPv6 server can be shared with regular DHCPv6 users as well.
4.5. Router-Solicit Trigger
The following example shows a router-solicit triggered configuration.
To add authentication to the above configuration, there are two options.
- For RADIUS authentication, similar to DHCP and PPP authentication, add a RADIUS policy under the group interface.
- For LUDB, add the following to the router-solicit configuration.
4.6. SLAAC Address Assignment
After a RS is received to trigger the creation of a SLAAC host, address assignment can be provided statically or dynamically.
4.7. Static SLAAC Prefix Assignment
If using RADIUS, the attribute “framed-ipv6-prefix” VSA is used. The attribute must be a /64 prefix.
4.8. Dynamic SLAAC Prefix Assignment
SLAAC prefix can be dynamically assigned to a user at real time. Prefixes are assignment through the local DHCPv6 pool. Therefore a DHCPv6 pool must be defined first. The following displays an example configuration.
To associate the DHCPv6 server for SLAAC address assignment, the following configuration is used. Notice the server name configured under local-address-assignment dhcp6-server matches the name configured under the DHCPv6 pool.
In order to specify the pool to be used for SLAAC prefix assignment, the pool name can either be returned from LUDB or RADIUS.
If using RADIUS, the attribute “Alc-slaac-ipv6-pool” is used.
If using LUDB, the following configuration is used.
In this example, the pool named “pool-01” provisioned in the LUDB or returned from RADIUS will match the pool name configured in the DHCP6 server. A prefix from the 2001::/32 pool will be assigned to the SLAAC subscribers.