Subscriber Services: Enhanced DHCP dual-stack

Subscriber management supports a single-session DHCP dual-stack model that provides a more efficient configuration and management of dual-stack subscribers. The single-session dual-stack model addresses session-related inefficiencies that exist in the traditional dual-stack-for example, the new model requires single sessions for authentication and accounting, as opposed to multiple sessions that are often needed in a traditional dual-stack configuration. The single-session dual-stack model also simplifies router configuration, reduces RADIUS message load, and improves accounting session performance for subscriber households with dual-stack environments.