AG
Use this command to redistribute subscriber aggregate routes to BGP. Subscriber aggregate routes are pre-provisioned prefixes that BGP announces to its peers before the subscribers come up. Therefore, when the subscriber does come up, the convergence is faster. The subscriber aggregate prefixes are installed in the routing table with a null0 next-hop so that no packet flows are forwarded until the subscriber is actually up. To take advantage of this feature in terms of its scalability, do not redistribute other forms of subscriber routes to BGP, including "redistribute subscriber," "redistribute subscriber static," and "redistribute subscriber address." The subscriber aggregate prefix should be shorter than the actual subscriber prefix (which typically are /32 prefixes). Otherwise, if only redistribute subscriber aggregate is configured, then BGP will withdraw the prefix when the subscriber comes up.