I have looking at the bootstrap source and seem to understand it for the most part. This is what I do not follow:

(1) New node joins and doesn't advertise its token.
(2) Requests nodes to send it data. The nodes that need to send it data first flush memtables and then transfer SSTables.

Once the streaming is over the new node advertises its token and starts handling reads and writes correct? But what happens to keys that are being written to the old nodes after the memtables have been dumped. Looks like there is a window where keys would be going to the old nodes and not making it to the new nodes. Am I missing something here.