QUIC short header packets only contain the destination connection ID and not the length of the destination connection ID. How can a QUIC client retrieve the connection ID without the length required to identify the connection?

Further, the connection ID can be of variable sizes, and the same connection can have multiple connection IDs. So, length is required to identify the connection ID.

Also, QUIC doesn’t restrict that one UDP connection to use one QUIC connection. Hence, multiple QUIC connections can go through one UDP connection.

What if the two connections have the same prefix for the connection IDs? I guess just checking the connection ID match doesn’t work.

I tried reading RFCs and other blogs but couldn’t get clarity. Please let me know how do clients deterministically determine the connection ID from short header packets.