On my system I have 3 gateways with 3 different internet providers. I want to add some QoS (traffic prioritization, or per traffic limitaion) rules, different for each gateway. My new queue with parent interface (for ex. ethernet1) does not work. It works only with parent global-out.
All 3 gateways have different bandwidth and as I know, to work properly traffic prioritization, max-limit must be defined.
My question is: in my case, may I do queue trees with interface as parent?
It depends on what you are trying to do. Yes Queue trees would be the way to go for you. But there is one thing to keep in mind, the parent that you place queue on is only going to affect the traffic leaving that interface. So if you want to queue download traffic, you need to have the parent on the LAN. If you are queuing upload traffic, then the queue(s) going on the WAN interface(s). The router cannot control the traffic it has or is receiving on an interface, it can only control what it sends out of said interface. Keep that in mind and you should be set to go.