You would need a pretty intense QoS system built for this if you are using something like TCP for this using two different connections. Underneath it would still use IPv4/6 packets and you only have so much bandwidth. The bulk transfer channel might stall the transfer of control packets temporarily.

You would need to tightly control and multiplex the messages yourself, needing to do this in one connection or using something like TCP priority flag.

Personally I just think that TCP is a shitty protocol for building applications. In almost every use case either UDP or SCTP are a better choice. With raw UDP datagrams you aren’t guaranteed delivery but it’s great for the kind of telemetry where the last message in is what matters. You can also build quite flexible stuff on top of it.

SCTP gives you in sequence reliable datagrams and congestion control. This means you don’t have to devise message length communication into your application layer protocol and can rely on your transport. It also has multiplexing built right in. If it had a built in checksum it would truly be ideal. Not sure if something like secure communication really belongs at this level but if it had that I double we would ever use anything else. From SCTP’s Wikipedia page:

> SCTP applications submit data for transmission in messages (groups of bytes) to the SCTP transport layer. SCTP places messages and control information into separate chunks (data chunks and control chunks), each identified by a chunk header. The protocol can fragment a message into multiple data chunks, but each data chunk contains data from only one user message. SCTP bundles the chunks into SCTP packets. The SCTP packet, which is submitted to the Internet Protocol, consists of a packet header, SCTP control chunks (when necessary), followed by SCTP data chunks (when available).