Hi, I am assuming that you are talking about Telstra Ethernet Access services as they are particularly bad in dropping packets which exceed the maximum service speed, nothing like BDAS services for bursting but a lot cheaper so you need to learn to work with them, even on Cisco kit they can be tricky to get working right, we have spent countless hours with our partners and Telstra getting these to work right.
We have done a lot of work with these and resell them so it was worth our while to try and get it right, the only real option was to use very minimal bursting because the burst threshold is only 4ms and Mikrotik can't support that.
The settings which we find work the best are as follows, this example is for a 20M service, but settings can be adjusted accordingly, just use the on-boarding guide for reference values depending on the service you are installing.
Work out values like this....
Burst speed = L2 service speed x 0.98 (Max realistic L3 speed with overheads)
Burst time = 1s
Shaping Burst (EBS) = 320kbit/s (from Telstra on-boarding guide and is different for each speed and traffic class)
Limit At = Burst Speed - Shaping Burst
Max Limit = Burst Speed - Shaping Burst
So settings for a 20M service are as follows:
Burst Speed = 19600k
Burst Time - 1s
Shaping Burst = 320kbit/s
Limit At = 19280k
Max Limit = 19280k
We also use a PFIFO queue with a size of 200 packets which is just under the 320k EBS size.
Obviously you need this on each end of the vlan, but we find that this flat lines comfortably just a smidge under 20M which doesn't cause the carrier to drop packets for us
Good luck !