A framing story is a term used to describe a peripheral, outer narrative that literally "frames" the central, main narrative. This is a common technique used in Gothic literature, and serves to distance the narrative from the reader by introducing a series of narrative layers through which the story is mediated. A classic example of this technique is in Wuthering Heights, where the central story of Cathy and Heathcliff is narrated to Lockwood by Nelly Dean who tells us the story. Thus the reader is separated from the action through both time and a series of narrators.
Based on this definition, Brave New World does not actually have a framing story or framing narrative. There is no separate story or story inside a story - it is complete in itself.