Port priority

Hi, i am an ISP. I receive connectivity from the main ISP and the redistribute it using mikrotik. I am using the simple queue feature to cap my customer speeds. They use authentication software to connect to the main internet provider. The problem I am facing is that some of my users are heavy downloaders. Due to that their connection gets logged out automatically after some time. Inorder to solve this problem I need to give priority to port 6699 which is used by the authentication software. Can you please guide me on how to do it on mikrotik.
Nelson

you can mark packets coming to/from the port 6699. And mark everything other with different mark-floe. Then use these flow under ‘/queue tree’ to give priorities - 1 is the highest, 8 - the lowest.

Edgars

I understood what you said and did the following for input and output rules.

/ip firewall mangle> add dst-address=10.16.13.0/24 src-port=6699 mark-flow=flow_in
/ip firewall mangle> add src-address=10.16.13.0/24 dst-port=6699 mark-flow=flow_out

I added the following in queue tree and used winbox to give priority ‘1’

/queue tree> add name=flow_in parent=phoenix_slot4 flow=net4_in max-limit=128000
/queue tree> add name=flow_out parent=phoenix_slot4 flow=net4_out max-limit=128000

I have the following doubts now :
a) Are the above commands right?
b) How do i mark everything other in mangle with different mark-flow?
c) Is it important to mark the rest or will it work by giving just one port the priority
d) Why was the rule added to queue tree. Wont simple queue do the job?
e) The ‘flow_in’ shows utilisation equivalent to the entire link utilisation although only port 6699 is marked. Any error in config by me?

Thanks in advance
Nelson