"We are using a PC with RouterOS v2.9.17 to handle the bandwidth QoS for our 512kbps (downlink) Internet backbone. Our subscribers are divided into groups via HTB queue tree, where four (4) groups (queue class) are created each with 128kbps MIR. In any one group we have about five (5) subscribers (on a 1:5 contention ratio). A queue tree is defined for each of these subscribers and each subscriber queue tree is given an MIR setting of 128kbps, thereby competing equally for the 128kbps pipeline allocated to the group. Priority is set the same for all. We use RED for all queue types with default settings.
Our problem is that although traffic shaping works generally, across groups and within groups, there seem to be an issue of “sluggish” subscriber’s ability to obtain full 128kbps MIR. For example when nobody is using the system and the entire 512kbps pipeline is available, any one subscriber can only obtain up to 90kbps donwlink. Uplink spare capacity at that point is plenty. No subscriber seem to be able to get the full 128kbps downlink MIR allocation, even at off-peak times. No one can even get past 100kbps.
Our subscribers are connected via wireless links and the Internet backbone is DVB-VSAT type. The RouterOS PC CPU, memory and disk resource utilization is very low, so resource is not an issue. We are considering inflating MIR allocations to compensate for this sluggish behaviour but would be interested to find out if there is a more elegant approach."