I have an ADSL connection at home in Tata with only about 800kbit/s upload bandwidth. I had to figure out how I can prioritize VoIP traffic with my new RouterBoard 750GL.

First my upload had to be throttled down in the RouterBoard a little below my ADSL upload speed. I added a new queue in the Queues window -> Queue Tree:

“inti” is my ASDL PPPoE interface. After this, I created 8 subqueues for each available priority (RouterOS supports 8 priorities):

I’ve set the “default-upload” queue for the parent of each subqueue and set the packet marks to “prio1” for the queue with priority=1, “prio2” for the queue with priority=2 and so on. So for example the packets marked as “prio5” will go to the queue which matches packets marked as “prio5” and so they will have priority 5.

After I’ve done adding the 8+1 queues, I opened IP -> Firewall -> Mangle and added the packet marking rules to the postrouting chain:

I mainly followed the marking rules described here (look at the QoS Example section). By default, every outgoing packet is marked with “prio6”, and UDP packets are “prio2” (for VoIP QoS).

I tested my configuration with iperf and speedtest.net.