SwarmBuilder, fallback transports and kademlia routing

[b-zee]

I'm looking into supporting two transports: QUIC and WebSockets. Now, preferably QUIC is the main transport. ws would be supported to let clients connect to a kademlia network.

Reading the docs on or_transport it appears transports have an order, but with SwarmBuilders methods like with_websocket I'm not sure if that is added as 'fallback' or the main transport.

I assume the ws addresses will have to be included in the routing table so as to support a client kademlia behavior that supports only ws. How do we prefer to let the nodes communicate over QUIC if possible? As QUIC is supposed to be more efficient, it's preferable to have node-node communication over QUIC.

Now I haven't made a PoC for this yet, so can't confirm if this all 'just works', but would greatly appreciate a high-ish level overview of what would happen with kademlia. E.g., through the use of identify I guess the (ws) listen addresses/transports will be known for all nodes and included in the routing table?