An SLAAC host prefix can be replaced with the VSA Alc-Ipv6-Slaac-Replacement-Prefix. This VSA is only supported through CoA or through the tools>subscr-mgmt>coa command. When a CoA is triggered, the original SLAAC host session terminates from the BNG. Depending on the accounting mode, an accounting stop message may be sent. Immediately following the termination of the original SLAAC host session, an SLAAC host with the new replacement prefix is created on the system. The SLAAC host inherits all the original host attributes, such as the subscriber profile and SLA profile. Nokia recommends against combining the VSA Alc-Ipv6-Slaac-Replacement-Prefix with other VSAs. An error in any of the VSAs can cause the SLAAC host recreation to fail. Service can only be restored after the subscriber performs an address request and authenticates.
The RA prefix replacement generates a single router advertisement containing both the old and new prefixes. The old prefix had both the valid and preferred lifetime parameters set to 0, informing the subscriber to deprecate the prefix as soon as possible. The new prefix has the valid and preferred lifetime parameters set as per the operator configuration. The subscriber can continue to use the old prefix for up to two hours after the RA. During the two hours, the 7750 SR drops subscriber traffic that does not match the anti-spoof criteria.
This feature is supported on an MCS setup. For persistence, the replacement SLAAC prefix is stored as the subscriber new prefix.
SLAAC prefixes that were assigned through local address assignment cannot be replaced. This feature ensures that when SLAAC replacement is performed, the address origin is not changed. This feature only replaces SLAAC host prefixes and cannot, for example, replace a DHCPv6 host with an SLAAC prefix. This feature is not supported for PPPoE sessions.