Integrate Multipath QUIC discussion on Multicast channel

[louisna]

Hello, again!

Here is some text about the integration of Multipath QUIC into Multicast QUIC. This is based on the Arxiv paper. It discusses how Multipath QUIC is integrated to easily deploy a Multicast QUIC channel for the client. This enables efficient unicast fall-back and unicast retransmissions seamlessly and without many changes in the current Multipath QUIC draft. The two major changes are:

• Using a different cryptographic context for each path. The "unicast" path uses the context derived during the connection establishment (ensuring a secure path between the server and the client). Each "multicast" path uses a different key derived by the server and advertised to all multicast clients.
• Clients must not send data/frames on the "multicast" path.

The text is just here to trigger discussion, and to converge into something that can fit in the draft.

[MaxF12]

LGTM, I think the "creation of the path" part is semantics, as to it's not really clear (at least to me) what counts as the "creation" of a new path. Is it the advertisement of the server to the client or when the client actually follows the instructions and joins the channel?

Why do you want to remove the part about transparency?

[louisna]

Why do you want to remove the part about transparency?

This was not made on purpose, sorry. I reverted it.