Do routers prioritize control traffic?

[Christos Papadopoulos <christos () CS ColoState EDU>]

I know routers today have the ability to prioritize
traffic, but last I heard, these controls are not
often used for user traffic (let's not discuss
net neutrality here).

Are they used for control (e.g., routing) traffic?

Please say a bit more than "It depends!" :-)
Our students are interested in real-world practices.

Answers on or off list are welcome.

Christos Papadopoulos
Colorado State University.